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  • 1. Bergqvist, J.
    et al.
    Tress, W.
    Forchheimer, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Melianas, A.
    Tang, Z.
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Inganäs, O.
    New method for lateral mapping of bimolecular recombination in thin-film organic solar cells2016In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 8, p. 1096-1108Article in journal (Refereed)
    Abstract [en]

    The best organic solar cells are limited by bimolecular recombination. Tools to study these losses are available; however, they are only developed for small area (laboratory-scale) devices and are not yet available for large area (production-scale) devices. Here we introduce the Intermodulation Light Beam-Induced Current (IMLBIC) technique, which allows simultaneous spatial mapping of both the amount of extracted photocurrent and the bimolecular recombination over the active area of a solar cell. We utilize the second-order non-linear dependence on the illumination intensity as a signature for bimolecular recombination. Using two lasers modulated with different frequencies, we record the photocurrent response at each modulation frequency and the bimolecular recombination in the second-order intermodulation response at the sum and difference of the two frequencies. Drift-diffusion simulations predict a unique response for different recombination mechanisms. We successfully verify our approach by studying solar cells known to have mainly bimolecular recombination and thus propose this method as a viable tool for lateral detection and characterization of the dominant recombination mechanisms in organic solar cells. We expect that IMLBIC will be an important future tool for characterization and detection of recombination losses in large area organic solar cells.

  • 2.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tress, Wolfgang
    Laboratory of Photonics and Interfaces, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
    Forchheimer, Daniel
    Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Haviland, David
    Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    New method for lateral mapping of bimolecular recombination in thin film organic solar cells2016In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 8, p. 1096-1108Article in journal (Refereed)
    Abstract [en]

    The best organic solar cells are limited by bimolecular recombination. Tools to study these losses are available; however, they are only developed for small area (laboratory-scale) devices and are not yet available for large area (production-scale) devices. Here we introduce the Intermodulation Light Beam-Induced Current (IMLBIC) technique, which allows simultaneous spatial mapping of both the amount of extracted photocurrent and the bimolecular recombination over the active area of a solar cell. We utilize the second-order non-linear dependence on the illumination intensity as a signature for bimolecular recombination. Using two lasers modulated with different frequencies, we record the photocurrent response at each modulation frequency and the bimolecular recombination in the second-order intermodulation response at the sum and difference of the two frequencies. Drift-diffusion simulations predict a unique response for different recombination mechanisms. We successfully verify our approach by studying solar cells known to have mainly bimolecular recombination and thus propose this method as a viable tool for lateral detection and characterization of the dominant recombination mechanisms in organic solar cells. We expect that IMLBIC will be an important future tool for characterization and detection of recombination losses in large area organic solar cells.

  • 3.
    Broman, Lars
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Thermophotovoltaics bibliography1995In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 3, no 1, p. 65-74Article in journal (Refereed)
    Abstract [en]

    A bibliography containing 200 entries on thermophotovoltaic conversion of energy between 1960 and 1995 has been compiled. The entries are categorized with respect to type and contents.

  • 4.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB, Vallvägen 5, Uppsala,Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Secondary phase formation and surface modification from a high dose KF-post deposition treatment of (Ag,Cu)(In,Ga)Se-2 solar cell absorbers2019In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 27, no 3, p. 220-228Article in journal (Refereed)
    Abstract [en]

    In this study, we assessed the potential of KF-post deposition treatment (PDT) performed on a silver-alloyed Cu (In,Ga)Se-2 (ACIGS) solar absorber. ACIGS absorbers with Ag/Ag + Cu ratio (Ag/I) close to 20% were co-evaporated on a Mo-coated glass substrate and exposed to in-situ KF-PDT of various intensities. The current-voltage characteristics indicated that an optimized PDT can be beneficial, increasing in our study the median V-oc and efficiency values by +48 mV and + 0.9%(abs) (from 728 mV and 16.1% efficiency measured for the sample without PDT), respectively. However, an increased KF-flux during PDT resulted in a net deterioration of the performance leading to median V-oc and efficiency values as low as 503 mV and 4.7%. The chemical composition analysis showed that while the reference absorber without any post deposition treatment (PDT) was homogeneous, the KF-PDT induced a clear change within the first 10 nm from the surface. Here, the surface layer composition was richer in K and In with an increased Ag/I ratio, and its thickness seemed to follow the KF exposure intensity. Additionally, high-dose KF-PDT resulted in substantial formation of secondary phases for the ACIGS. The secondary phase precipitates were also richer in Ag, K, and In, and electron and X-ray diffraction data match with the monoclinic C 1 2/c 1 space group adopted by the Ag-alloyed KInSe2 phase. It could not be concluded whether the performance loss for the solar cell devices originated from the thicker surface layer or the presence of secondary phases, or both for the high-dose KF-PDT sample.

  • 5.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Surface Modification And Secondary Phase Formation From a High Dose KF-Post Deposition Treatment of (Ag,Cu)(In,Ga)Se2 Solar Cell AbsorbersIn: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159XArticle in journal (Refereed)
    Abstract [en]

    In this study we assessed the potential of KF-Post Deposition Treatment (PDT) performed on a silver-alloyed Cu(Inx,Ga1-x)Se2 (ACIGS) solar absorber. ACIGS absorbers with Ag/Ag+Cu ratio (Ag/I) close to 20% were co-evaporated on a Mo-coated glass substrate and exposed to in-situ KF-PDT of various intensities. The current-voltage characteristics indicated that an optimized PDT can be beneficial, increasing in our study the median Voc and efficiency values by +48 mV and +0.9 %abs (from 728 mV and 16.1 % efficiency measured for the sample without PDT), respectively. However, an increased KF-flux during PDT resulted in a net deterioration of the performance leading to median Voc and efficiency values as low as 503 mV and 4.7 %. The chemical composition analysis showed that while the reference absorber without any PDT was homogeneous, the KF-PDT induced a clear change within the first 10 nm from the surface. Here, the surface layer composition was richer in K and In with an increased Ag/I ratio, and its thickness seemed to follow the KF exposure intensity. Additionally, high-dose KF-PDT resulted in substantial formation of secondary phases for the ACIGS. The secondary phase precipitates were also richer in Ag, K and In, and Electron and X-ray diffraction data match with the monoclinic C 1 2/c 1 space group adopted by the Ag-alloyed KInSe2 (AKIS) phase. It could not be concluded whether the performance loss for the solar cell devices originated from the thicker surface layer or the presence of secondary phases, or both for the high-dose KF-PDT sample.

  • 6.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thersleff, Thomas
    Stockholms Univ, Nat Skapliga Fak, Inst Mat & Miljokemi, Stockholm.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wallin, Erik
    Solibro Research AB, Uppsala, Sweden.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB, Uppsala, Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Deep surface Cu depletion induced by K in high-efficiency Cu(In,Ga)Se2 solar cell absorbers2018In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, no 9, p. 730-739Article in journal (Refereed)
    Abstract [en]

    In this work, we used K‐rich glass substrates to provide potassium during the coevaporation of Cu(In,Ga)Se2 (CIGS) absorber layers. Subsequently, we applied a postdeposition treatment (PDT) using KF or RbF to some of the grown absorbers. It was found that the presence of K during the growth of the CIGS layer led to cell effi- ciencies beyond 17%, and the addition of a PDT pushed it beyond 18%. The major finding of this work is the observation of discontinuous 100‐ to 200‐nm‐deep Cu‐ depleted patches in the vicinity of the CdS buffer layer, correlated with the presence of K during the growth of the absorber layer. The PDT had no influence on the forma- tion of these patches. A second finding concerns the composition of the Cu‐depleted areas, where an anticorrelation between Cu and both In and K was measured using scanning transmission electron microscopy. Furthermore, a steeper Ga/(In+Ga) ratio gradient was measured for the absorbers grown with the presence of K, suggesting that K hinders the group III element interdiffusion. Finally, no Cd in‐diffusion to the CIGS layer could be detected. This indicates that if CdCu substitution occurs, either their concentration is below our instrumental detection limit or its presence is contained within the first 6 nm from the CdS/CIGS interface.

  • 7.
    Giraldo, Sergio
    et al.
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Thersleff, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Larramona, Gerardo
    IMRA Europe SAS, 220 Rue Albert Caquot, F-06904 Sophia Antipolis, France..
    Neuschitzer, Markus
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Pistor, Paul
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Perez-Rodriguez, Alejandro
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain.;Univ Barcelona, IN2UB, C Marti & Franques 1, E-08028 Barcelona, Spain..
    Moisan, Camille
    IMRA Europe SAS, 220 Rue Albert Caquot, F-06904 Sophia Antipolis, France..
    Dennler, Gilles
    IMRA Europe SAS, 220 Rue Albert Caquot, F-06904 Sophia Antipolis, France..
    Saucedo, Edgardo
    Catalonia Inst Energy Res, Jardins Dones Negre 1, St Adria De Besos 08930, Barcelona, Spain..
    Cu2ZnSnSe4 solar cells with 10.6% efficiency through innovative absorber engineering with Ge superficial nanolayer2016In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 10, p. 1359-1367Article in journal (Refereed)
    Abstract [en]

    In our recently published work, the positive effect of a Ge nanolayer introduced into the processing of Cu2ZnSnSe4 absorbers (CZTSe) was demonstrated. In this contribution, the complete optimization of this new approach is presented for the first time. Hence, the optimum Ge nanolayer thickness range is defined in order to achieve an improved performance of the devices, obtaining a record efficiency of 10.6%. By employing this optimized approach, the open-circuit voltage (V-OC) is boosted for our pure selenide CZTSe up to 489 mV, leading to V-OC deficit among the lowest reported so far in kesterite technology. Additionally, two important effects related to the Ge are unambiguously demonstrated that might be the origin of the V-OC boost: the improvement of the grain size and the corresponding crystalline quality, and the interaction between Ge and Na that allows for dynamic control over the CZTSe doping. Finally, evidences pointing to the origin of the deterioration of devices properties for large Ge concentrations are presented.

  • 8.
    Hultqvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Evaluation of Zn-Sn-O buffer layers for CuIn0.5Ga0.5Se2 solar cells2011In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 19, no 4, p. 478-481Article in journal (Refereed)
    Abstract [en]

    Thin Zn-Sn-O films are evaluated as new buffer layer material for Cu(In,Ga)Se-2-based solar cell devices. A maximum conversion efficiency of 13.8% (V-oc = 691 mV, J(sc)(QE) = 27.9 mA/cm(2), and FF = 71.6%) is reached for a solar cell using the Zn-Sn-O buffer layer which is comparable to the efficiency of 13.5% (V-oc - 706 mV, J(sc)(QE) - 26.3 mA/cm(2), and FF = 72.9%) for a cell using the standard reference CdS buffer layer. The open circuit voltage (V-oc) and the fill factor (FF) are found to increase with increasing tin content until an optimum in both parameters is reached for Sn/(Zn+Sn) values around 0.3-0.4.

  • 9.
    Hultqvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zimmermann, Uwe
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Growth kinetics, properties, performance, and stability of atomic layer deposition Zn–Sn–O buffer layers for Cu(In,Ga)Se2 solar cells2012In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 20, no 7, p. 883-891Article in journal (Refereed)
    Abstract [en]

    A new atomic layer deposition process was developed for deposition of Zn–Sn–O buffer layers for Cu(In,Ga)Se2 solar cells with tetrakis(dimethylamino) tin, Sn(N(CH3)2)4, diethyl zinc, Zn(C2H5)2, and water, H2O. The new processgives good control of thickness and [Sn]/([Sn]+[Zn]) content of the films. The Zn–Sn–O films are amorphous as foundby grazing incidence X-ray diffraction, have a high resistivity, show a lower density compared with ZnO and SnOx, andhave a transmittance loss that is smeared out over a wide wavelength interval. Good solar cell performance was achievedfor a [Sn]/([Sn]+[Zn]) content determined to be 0.15–0.21 by Rutherford backscattering. The champion solar cell with aZn–Sn–O buffer layer had an efficiency of 15.3% (Voc=653mV, Jsc(QE)=31.8mA/cm2, and FF=73.8%) compared with15.1% (Voc=663mV, Jsc(QE)=30.1mA/cm2, and FF=75.8%) of the best reference solar cell with a CdS buffer layer. Thereis a strong light-soaking effect that saturates after a few minutes for solar cells with Zn–Sn–O buffer layers after storage in thedark. Stability was tested by 1000h of dry heat storage in darkness at 85°C, where Zn–Sn–O buffer layers with a thicknessof 76nm retained their initial value after a few minutes of light soaking.

  • 10. Janßen, Lars
    et al.
    Rinio, Markus
    Borchert, Dietmar
    Windgassen, Horst
    Bätzner, D. L.
    Kurz, H.
    Passivating thin bifacial silicon solar cells for industrial production2007In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 15, no 6, p. 469-475Article in journal (Refereed)
    Abstract [en]

    A scheme for passivating thin multi-crystalline silicon solar cells compatible to massproduction is presented. Wafers with a thickness of 180 mm were processed into solarcells. The otherwise severe bowing has been avoided by reduced aluminium coverageon the rear surface. The process scheme includes a silicon nitride firing through stepfor conventional screen printed contacts, where a silicon nitride layer on the rearsurface acts as surface passivation layer and enables a gain in efficiency of 0.6%[abs.].

  • 11.
    Keller, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chalvet, Francis
    Solibro Res AB, Vallvagen 5, S-75151 Uppsala, Sweden.
    Joel, Jonathan
    Solibro Res AB, Vallvagen 5, S-75151 Uppsala, Sweden.
    Aijaz, Asim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Res AB, Vallvagen 5, S-75151 Uppsala, Sweden.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Effect of KF absorber treatment on the functionality of different transparent conductive oxide layers in CIGSe solar cells2018In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, no 1, p. 13-23Article in journal (Refereed)
    Abstract [en]

    This contribution studies the impact of the KF-induced Cu(In,Ga)Se2 (CIGSe) absorber modification on the suitability of different transparent conductive oxide (TCO) layers in solar cells. The TCO material was varied between ZnO:Al (AZO), ZnO:B (BZO), and In2O3:H (IOH). It is shown that the thermal stress needed for optimized TCO properties can establish a transport barrier for charge carriers, which results in severe losses in fill factor (FF) for temperatures >150°C. The FF losses are accompanied by a reduction in open circuit voltage (Voc) that might originate from a decreased apparent doping density (Nd,app) after annealing. Thermally activated redistributions of K and Na in the vicinity of the CdS/(Cu,K)-In-Se interface are suggested to be the reason for the observed degradation in solar cell performance. The highest efficiency was measured for a solar cell where the absorber surface modification was removed and a BZO TCO layer was deposited at a temperature of 165°C. The presented results highlight the importance of well-designed TCO and buffer layer processes for CIGSe solar cells when a KF post deposition treatment (KF-PDT) was applied.

  • 12.
    Keller, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bifacial Cu(In,Ga)Se2 solar cells using hydrogen‐doped In2O3 films as a transparent back contact2018In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, no 10, p. 846-858Article in journal (Refereed)
    Abstract [en]

    Hydrogen‐doped In2O3 (IOH) films are used as a transparent back contact in bifacial Cu(In,Ga)Se2 (CIGS) solar cells. The effect of the IOH thickness and the impact of the sodium incorporation technique on the photovoltaic parameters are studied, and clear correlations are observed. It is shown that a loss in short circuit current density (JSC) is the major limitation at back side illumination. The introduction of a thin Al2O3 layer on top of the IOH significantly increases the collection efficiency (ϕ(x)) for electrons generated close to the back contact. In this way, the JSC loss can be mitigated to only ~ 25% as compared with front side illumination. The Al2O3 film potentially reduces the interface defect density or, alternatively, creates a field effect passivation. In addition, it prevents the excessive formation of Ga2O3 at the CIGS/IOH interface, which is found otherwise when a NaF layer is added before absorber deposition. Consequently, detrimental redistributions in Ga and In close to the back contact can be avoided. Finally, a bifacial CIGS solar cell with an efficiency (η) of η = 11.0% at front and η = 6.0% at back side illumination could be processed. The large potential for further improvements is discussed.

  • 13.
    Keller, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindahl, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Potential gain in photocurrent generation for Cu(In,Ga)Se2 solar cells by using In2O3 as a transparent conductive oxide layer2016In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 1, p. 102-107Article in journal (Refereed)
    Abstract [en]

    This study highlights the potential of atomic layer deposited In2O3 as a highly transparent and conductive oxide (TCO)layer in Cu(In,Ga)Se2 (CIGSe) solar cells. It is shown that the efficiency of solar cells which use Zn-Sn-O (ZTO) as an alternativebuffer layer can be increased by employing In2O3 as a TCO because of a reduction of the parasitic absorption inthe window layer structure, resulting in 1.7 mA/cm2 gain in short circuit current density (Jsc). In contrast, a degradation ofdevice properties is observed if the In2O3 TCO is combined with the conventional CdS buffer layer. The estimated improvementfor large-scale modules is discussed.

  • 14.
    Keller, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Shariati, Masumeh-Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Aijaz, Asim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Using hydrogen‐doped In2O3 films as a transparent back contact in (Ag,Cu)(In,Ga)Se2 solar cells2018In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, no 3, p. 159-170Article in journal (Refereed)
    Abstract [en]

    This study evaluates the potential of hydrogen‐doped In2O3 (IOH) as a transparent back contact material in (Agy,Cu1‐y)(In1‐x,Gax)Se2 solar cells. It is found that the presence of Na promotes the creation of Ga2O3 at the back contact during (Agy,Cu1‐y)(In1‐x,Gax)Se2 growth. An excessive Ga2O3 formation results in a Ga depletion, which extends deep into the absorber layer. Consequently, the beneficial back surface field is removed and a detrimental reversed electrical field establishes. However, for more moderate Ga2O3 amounts (obtained with reduced Na supply), the back surface field can be preserved. Characterization of corresponding solar cells suggests the presence of an ohmic back contact, even at absorber deposition temperatures of 550°C. The best solar cell with an IOH back contact shows a fill factor of 74% and an efficiency (η) of 16.1% (without antireflection coating). The results indicate that Ga2O3 does not necessarily act as a transport barrier in the investigated system. Observed losses in open circuit voltage (VOC) as compared to reference samples with a Mo back contact are ascribed to a lower Na concentration in the absorber layer.

  • 15.
    Landelius, Tomas
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Andersson, Sandra
    SMHI, Core Services.
    Abrahamsson, Roger
    Modelling and forecasting PV production in the absence of behind-the-meter measurements2019In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 27, no 11, p. 990-998Article in journal (Refereed)
  • 16.
    Larsson, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Shariati, M. Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Frisk, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kosyak, Volodymyr
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Record 1.0 V open-circuit voltage in wide band gap chalcopyrite solar cells2017In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 25, p. 755-763Article in journal (Refereed)
    Abstract [en]

    Tandem solar cell structures require a high‐performance wide band gap absorber as top cell. Apossible candidate is CuGaSe2, with a fundamental band gap of 1.7 eV. However, a significantopen‐circuit voltage deficit is often reported for wide band gap chalcopyrite solar cells likeCuGaSe2. In this paper, we show that the open‐circuit voltage can be drastically improved in wideband gap p‐Cu(In,Ga)Se2and p‐CuGaSe2devices by improving the conduction band alignment tothe n‐type buffer layer. This is accomplished by using Zn1−xSnxOy, grown by atomic layer deposi-tion, as a buffer layer. In this case, the conduction band level can be adapted to an almost perfectfit to the wide band gap Cu(In,Ga)Se2and CuGaSe2materials. With an improved buffer bandalignment for CuGaSe2absorbers, evaporated in a 3‐stage type process, we show devicesexhibiting open‐circuit voltages up to 1017 mV, and efficiencies up to 11.9%. This is to the bestof our knowledge the highest reported open‐circuit voltage and efficiency for a CuGaSe2device.Temperature‐dependent current‐voltage measurements show that the high open‐circuit voltageis explained by reduced interface recombination, which makes it possible to separate theinfluence of absorber quality from interface recombination in future studies.

  • 17.
    Lindahl, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wätjen, Jörn Timo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ericson, Tove
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    The effect of Zn1−xSnxOy buffer layer thickness in 18.0% efficient Cd-free Cu(In,Ga)Se2 solar cells2013In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 21, no 8, p. 1588-1597Article in journal (Refereed)
    Abstract [en]

    The influence of the thickness of atomic layer deposited Zn1−xSnxOy buffer layers and the presence of an intrinsic ZnO layer on the performance of Cu(In,Ga)Se2 solar cells are investigated. The amorphous Zn1−xSnxOy layer, with a [Sn]/([Sn] + [Zn]) composition of approximately 0.18, forms a conformal and in-depth uniform layer with an optical band gap of 3.3 eV. The short circuit current for cells with a Zn1−xSnxOy layer are found to be higher than the short circuit current for CdS buffer reference cells and thickness independent. On the contrary, both the open circuit voltage and the fill factor values obtained are lower than the references and are thickness dependent. A high conversion efficiency of 18.0%, which is comparable with CdS references, is attained for a cell with a Zn1−xSnxOy layer thickness of approximately 13 nm and with an i-ZnO layer.

  • 18.
    Malm, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Influence from front contact sheet resistance on extracted diode parameters in CIGS solar cells2008In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 16, no 2, p. 113-121Article in journal (Refereed)
    Abstract [en]

    The extraction of one-diode model parameters from a current-voltage (J-V) curve is problematic, since the model is one-dimensional while real devices are indeed three-dimensional. The parameters obtained by fitting the model curve to experimental data depend on how the current is collected, and more specifically the geometry of the contact. This is due to the non-uniform lateral current flow in the window layers, which leads to different parts of the device experiencing different front contact voltage drop, and hence different operating points on the ideal J-V curve. In this work, finite element simulations of three-dimensional contact structures are performed and compared to experimental data on Cu(In,Ga)Se2-based solar cell devices. It is concluded that the lateral current flow can influence the extracted parameters from the one-diode model significantly if the resistivity of the front contact material is high, or if there is no current collecting grid structure. These types of situations may appear in damp heat-treated cells and module type cells, respectively.

  • 19.
    Malm, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Simulating Material Inhomogeneities and Defects in CIGS Thin-film Solar Cells2009In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 17, no 5, p. 306-314Article in journal (Refereed)
    Abstract [en]

    Thin-film CIGS solar cells are simulated using a hybrid model   consisting of a distributed form of the analytical one diode model   paired with a numerical finite element model of the d.c. conduction in   the front contact layers. Variations in material quality over the   substrate surface., from measured J-V curves, are incorporated into the   model and the effects of cell width and window layer thickness are evaluated for homogeneous and inhomogeneous material quality. Furthermore, the effects of discrete shunt defects of different sizes   are modelled, and in different positions on the cell surface. The  results from optimizing cell width and window layer thickness show that   the effects of material inhomogeneities include a small shift of the   optimal parameters together with a less pronounced maximum. As   expected, the defect size is important to the shunt conductance   parameter of the resulting J-V curves. The passivating effect of the highly resistive ZnO layer is confirmed.

  • 20. Naghavi, N.
    et al.
    Abou-Ras, D.
    Allsop, N.
    Barreau, N.
    Buecheler, S.
    Ennaoui, A.
    Fischer, C. -H
    Guillen, C.
    Hariskos, D.
    Herrero, J.
    Klenk, R.
    Kushiya, K.
    Lincot, D.
    Menner, R.
    Nakada, T.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Spiering, S.
    Tiwari, A. N.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Buffer layers and transparent conducting oxides for chalcopyrite Cu(In,Ga)(S,Se)(2) based thin film photovoltaics: Present status and current developments2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 6, p. 411-433Article in journal (Refereed)
    Abstract [en]

    The aim of the present contribution is to give a review on the recent work concerning Cd-free buffer and window layers in chalcopyrite solar cells using various deposition techniques as well as on their adaptation to chalcopyrite-type absorbers such as Cu(In,Ga)Se-2, CuInS2, or Cu(In,Ga)(S,Se)(2). The corresponding solar-cell performances, the expected technological problems, and current attempts for their commercialization will be discussed. The most important deposition techniques developed in this paper are chemical bath deposition, atomic layer deposition, ILGAR deposition, evaporation, and spray deposition. These deposition methods were employed essentially for buffers based on the following three materials: In2S3, ZnS, Zn1-xMgxO.

  • 21. Pettersson, Henrik
    et al.
    Gruszecki, Tadeusz
    Bernhard, Roman
    Haggman, Leif
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Boschloo, Gerrit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Edvinsson, Tomas
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    The monolithic multicell: A tool for testing material components in dye-sensitized solar cells2007In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 15, no 2, p. 113-121Article in journal (Refereed)
    Abstract [en]

    A multicell is presented as a tool for testing material components in encapsulated dye-sensitized solar cells. The multicell is based on a four-layer monolithic cell structure and an industrial process technology. Each multicell plate includes 24 individual well-encapsulated cells. A sulfur lamp corrected to the solar spectrum has been used to characterize the cells. Efficiencies up to 6.8% at a light-intensity of 1000 W/m(2) (up to 7.5% at 250 W/m(2)) have been obtained with an electrolyte solution based on gamma-butyrolactone. Additionally, a promising long-term stability at cell efficiencies close to 5% at 1000 W/m(2) has been obtained with an electrolyte based on glutaronitrile. The reproducibility of the cell performance before and after exposure to accelerated testing has been high. This means that the multicell can be used as an efficient tool for comparative performance and stability tests.

  • 22. Pettersson, Henrik
    et al.
    Gruszecki, Tadeusz
    Bernhard, Roman
    Haggman, Leif
    Gorlov, Mikhail
    Boschloo, Gerrit
    Edvinsson, Tomas
    Kloo, Lars
    Hagfeldt, Anders
    The monolithic multicell: A tool for testing material components in dye-sensitized solar cells2007In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 15, no 2, p. 113-121Article in journal (Refereed)
  • 23.
    Pettersson, Henrik
    et al.
    RISE, Swerea, Swerea IVF.
    Gruszecki, Tadeusz
    RISE, Swerea, Swerea IVF.
    Schnetz, Christine
    RISE, Swerea, Swerea IVF.
    Streit, Micha
    RISE, Swerea, Swerea IVF.
    Xu, Y.
    Royal Institute of Technology.
    Sun, L.
    Royal Institute of Technology.
    Gorlov, M.
    Royal Institute of Technology.
    Kloo, L.
    Royal Institute of Technology.
    Boschloo, G.
    Uppsala University.
    Häggman, L.
    Uppsala University.
    Hagfeldt, A.
    Uppsala University.
    Parallel-connected monolithic dye-sensitised solar modules2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 5, p. 340-645Article in journal (Refereed)
    Abstract [en]

    Light-soaking and high-temperature storage testing of monolithic dye-sensitised solar modules with total area module efficiencies above 5% have been performed. Our experiences from the development of a four-layer monolithic dyesensitised solar test cell for comparative testing of material components for dye-sensitised solar cells have directed our module development to a novel device design consisting of parallel-connection of individual monolithic cells. The results from the accelerated testing of the modules (total area of 17.0 cm2) with four parallel-connected cells (active area of 3.38 cm 2/cell) are equivalent to those obtained for the monolithic single test cells when using identical device components. The successful transfer from cell to module stability is an important milestone in our ambition to develop a low-cost Photovoltaic (PV) technology. Moreover, our results indicate that intensified research and development to define the procedures for relevant accelerated testing of dye-sensitised solar modules is urgently required. Copyright © 2010 John Wiley & Sons, Ltd.

  • 24. Pettersson, Henrik
    et al.
    Gruszecki, Tadeusz
    Schnetz, Christine
    Streit, Micha
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Boschloo, Gerrit
    Häggman, Leif
    Hagfeldt, Anders
    Parallel-connected monolithic dye-sensitised solar modules2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 5, p. 340-345Article in journal (Refereed)
    Abstract [en]

    Light-soaking and high-temperature storage testing of monolithic dye-sensitised solar modules with total area module efficiencies above 5% have been performed. Our experiences from the development of a four-layer monolithic dye-sensitised solar test cell for comparative testing of material components for dye-sensitised solar cells have directed our module development to a novel device design consisting of parallel-connection of individual monolithic cells. The results from the accelerated testing of the modules (total area of 17.0 cm(2)) with four parallel-connected cells (active area of 3.38 cm(2)/cell) are equivalent to those obtained for the monolithic single test cells when using identical device components. The successful transfer from cell to module stability is an important milestone in our ambition to develop a low-cost Photovoltaic (PV) technology. Moreover, our results indicate that intensified research and development to define the procedures for relevant accelerated testing of dye-sensitised solar modules is urgently required.

  • 25. Pettersson, Henrik
    et al.
    Gruszecki, Tadeusz
    Schnetz, Christine
    Streit, Micha
    Xu, Yunhua
    Sun, Licheng
    Gorlov, Mikhail
    Kloo, Lars
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Häggman, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Parallel-connected monolithic dye-sensitised solar modules2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 5, p. 340-345Article in journal (Refereed)
    Abstract [en]

    Light-soaking and high-temperature storage testing of monolithic dye-sensitised solar modules with total area module efficiencies above 5% have been performed. Our experiences from the development of a four-layer monolithic dye-sensitised solar test cell for comparative testing of material components for dye-sensitised solar cells have directed our module development to a novel device design consisting of parallel-connection of individual monolithic cells. The results from the accelerated testing of the modules (total area of 17.0 cm(2)) with four parallel-connected cells (active area of 3.38 cm(2)/cell) are equivalent to those obtained for the monolithic single test cells when using identical device components. The successful transfer from cell to module stability is an important milestone in our ambition to develop a low-cost Photovoltaic (PV) technology. Moreover, our results indicate that intensified research and development to define the procedures for relevant accelerated testing of dye-sensitised solar modules is urgently required.

  • 26.
    Pettersson, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Temperature-dependent current-voltage and lightsoaking measurements on Cu(In,Ga)Se2 solar cells with ALD-Zn1-xMgxO buffer layers2009In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 17, no 7, p. 460-469Article in journal (Refereed)
    Abstract [en]

    In this paper, lightsoaking and temperature-dependent current-voltage (JVT) measurements on Cu(In,Ga)Se2 solar cells with atomic layer deposited Zn1-xMgxO buffer layers are presented. A range of Mg concentrations are used, from pure ZnO (x=0) to 26% Mg (x=0·26). Since this kind of solar cells exhibit strong metastable behaviour, lightsoaking is needed prior to the JVT-measurements to enable fitting of these to the one-diode model. The most prominent effect of lightsoaking cells with Mg-rich buffer layers is an increased fill factor, while the effect on cells with pure ZnO buffer is mainly to increase Voc·. The activation energy is extracted from JVT-measurement data by applying three different methods and the ideality factors are fitted to two different models of temperature-dependence. A buffer layer consisting either of ZnO or Zn1-xMgxO with a minor Mg content gives solar cells dominated by interface recombination, which probably can be related to a negative conduction band offset. A relatively high Mg content in the buffer layer (x=0·21) leads to solar cells dominated by recombination in the space charge region. The recombination is interpreted as being tunnelling-enhanced. The situation in between these Mg concentrations is less clear. Before lightsoaking, the sample with x=0·12 has the highest efficiency of 15·3%, while after lightsoaking the sample with x=0·21 holds the best efficiency, 16·1%, exceeding the value for the CdS reference. The Jsc values of the Zn1-xMgxO cells surpass that of the reference due to the larger bandgap of Zn1-xMgxO compared to CdS.

  • 27.
    Platzer-Björkman, Charlotte
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zabierowski, P.
    Pettersson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Improved fill factor and open circuit voltage by crystalline selenium at the Cu(In,Ga)Se-2/buffer layer interface in thin film solar cells2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 4, p. 249-256Article in journal (Refereed)
    Abstract [en]

    A surface treatment by evaporated selenium on Cu(In,Ga)Se, (CIGS) is shown to improve open circuit voltage, V and in some cases fill factor, FF, in solar cells with CdS, (Zn,Mg)O or Zn(O,S) buffer layers. V increases with increasing amount of crystalline Se, while FF improves only for small amounts. The improvements are counteracted by a decreasing short circuit current assigned to absorption in hexagonal Se. Improved efficiency is shown for device structures with (Zn,Mg)0 and Zn(O,S) buffer layers by atomic layer deposition. Analysis by grazing incidence X-ray diffraction and photoelectron spectroscopy show partial coverage of the CIGS surface by hexagonal selenium. The effects on device performance from replacing part of the CIGS/buffer interface area by a Se/buffer junction are discussed.

  • 28.
    Rinio, Markus
    et al.
    Laboratory and Service Center, Fraunhofer Institute for Solar Energy Systems ISE, Auf der Reihe 2, 45884 Gelsenkirchen, Germany.
    Yodyunyong, Arthit
    Laboratory and Service Center, Fraunhofer Institute for Solar Energy Systems ISE, Auf der Reihe 2, 45884 Gelsenkirchen, Germany.
    Keipert-Colberg, Sinje
    Laboratory and Service Center, Fraunhofer Institute for Solar Energy Systems ISE, Auf der Reihe 2, 45884 Gelsenkirchen, Germany.
    Botchak Mouafi, Y. P.
    Laboratory and Service Center, Fraunhofer Institute for Solar Energy Systems ISE, Auf der Reihe 2, 45884 Gelsenkirchen, Germany.
    Borchert, Dietmar
    Laboratory and Service Center, Fraunhofer Institute for Solar Energy Systems ISE, Auf der Reihe 2, 45884 Gelsenkirchen, Germany.
    Montesdeoca-Santana, Amada
    Universidad de La Laguna, Avda Astrofísico Fco Sánchez, 2, 38206 La Laguna, Spain.
    Improvement of multicrystalline silicon solar cells by a low temperature anneal after emitter difusion2011In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 19, p. 165-169Article in journal (Refereed)
    Abstract [en]

    The influence of an annealing step at about 500 degree celsius after emitter diffusion of multicrystalline solar cells is investigated. Neighboring wafers from a silicon ingot were processed using different annealing durations and temperatures. The efficiency of the cells was measured and detailed light beam induced current measurements were performed. These show that mainly areas with high contents of precipitates near the crucible walls are affected by the anneal. An efficiency increase from 14.5 to 15.4% by a 2h anneal at 500 degree celsius was observed. The effect seems to be more likely external than internal gettering.

  • 29.
    Rönnelid, Mats
    et al.
    Dalarna University, School of Technology and Business Studies, Environmental Engineering.
    Karlsson, B
    Krohn, P
    Wennerberg, J
    Booster reflectors for PV modules in Sweden2000In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 8, p. 279-291Article in journal (Refereed)
  • 30.
    Salome, Pedro M. P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fjällström, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Szaniawski, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Leitao, Joaquim P.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fernandes, Paulo A.
    Teixeira, Jennifer P.
    Falcao, Bruno P.
    Zimmermann, Uwe
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    da Cunha, Antonio F.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    A comparison between thin film solar cells made from co-evaporated CuIn1-xGaxSe2 using a one-stage process versus a three-stage process2015In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 23, no 4, p. 470-478Article in journal (Refereed)
    Abstract [en]

    Until this day, the most efficient Cu(In,Ga)Se-2 thin film solar cells have been prepared using a rather complex growth process often referred to as three-stage or multistage. This family of processes is mainly characterized by a first step deposited with only In, Ga and Se flux to form a first layer. Cu is added in a second step until the film becomes slightly Cu-rich, where-after the film is converted to its final Cu-poor composition by a third stage, again with no or very little addition of Cu. In this paper, a comparison between solar cells prepared with the three-stage process and a one-stage/in-line process with the same composition, thickness, and solar cell stack is made. The one-stage process is easier to be used in an industrial scale and do not have Cu-rich transitions. The samples were analyzed using glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray diffraction, current-voltage-temperature, capacitance-voltage, external quantum efficiency, transmission/reflection, and photoluminescence. It was concluded that in spite of differences in the texturing, morphology and Ga gradient, the electrical performance of the two types of samples is quite similar as demonstrated by the similar J-V behavior, quantum spectral response, and the estimated recombination losses. 

  • 31.
    Salomé, Pedro M. P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fjällström, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Szaniawski, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zimmermann, Uwe
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    The effect of Mo back contact ageing on Cu(In,Ga)Se-2 thin-film solar cells2014In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 22, no 1, p. 83-89Article in journal (Refereed)
    Abstract [en]

    In this work, we investigate the effect of ageing Mo-coated substrates in a dry and N-2 flooded cabinet. The influence was studied by preparing Cu(In,Ga)Se-2 solar cells and by comparing the electrical performance with devices where the Mo layer was not aged. The measurements used for this study were current-voltage (J-V), external quantum efficiency (EQE), secondary ion mass spectroscopy (SIMS) and capacitance-voltage (C-V). It was concluded that devices prepared with the aged Mo layer have, in average, an increase of 0.8% in efficiency compared with devices that had a fresh Mo layer. Devices with aged Mo exhibited a nominal increase of 12.5mV of open circuit voltage, a decrease of 1.1mA/cm(-2) of short circuit current and a fill factor increase of 2.4%. Heat treatment of fresh Mo layers in oxygen atmosphere was also studied as an alternative to ageing and was shown to provide a similar effect to the aged device's performance. 

  • 32. Schleussner, S. M.
    et al.
    Törndahl, T.
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zimmermann, U.
    Wätjen, T.
    Edoff, M.
    Development of gallium gradients in three-stage Cu(In,Ga)Se2 co-evaporation processes2012In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 20, no 3, p. 284-293Article in journal (Refereed)
    Abstract [en]

    We use secondary-ion mass spectrometry, X-ray diffraction and scanning electron microscopy to investigate the development over time of compositional gradients in Cu(In,Ga)Se2 thin films grown in three-stage co-evaporation processes and suggest a comprehensive model for the formation of the well-known notch structure. The model takes into account the need for compensating Cu diffusion by movement of group-III ions in order to remain on the quasi-binary tie line and indicates that the mobilities of In and Ga ions differ. Cu diffuses towards the back in the second stage and towards the front in the third, and this is the driving force for the movement of In and Ga. The [Ga]/[In?+?Ga] ratio then increases in the direction of the respective Cu movement because In has a higher mobility at process conditions than has Ga. Interdiffusion of In and Ga can be considerable in the (In,Ga)2Se3 film of the first stage, but seems largely to cease in Cu(In,Ga)Se2 and shows no signs of being boosted by the presence of a Cu2Se layer.

  • 33.
    Schleussner, Sebastian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Pettersson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Surface engineering in Cu(In,Ga)Se2 solar cells2013In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 21, no 4, p. 561-568Article in journal (Refereed)
    Abstract [en]

    Surface modifications of 3-stage co-evaporated Cu(In,Ga)Se2 (CIGS) thin films are investigated by finishing the evaporation with gallium-free (CuInSe2, CIS) stages of various lengths. We find substantial interdiffusion of indium and gallium, smearing out the Ga/(Ga+In) profile so that the addition of a CIS layer merely lowers the gallium content at the surface. For the thinnest top layer, equivalent to 20 nm of pure CIS, we cannot detect any compositional difference compared to the reference device. The modification are evaluated both by electrical characterization of actual solar-cell devices and by electrical modelling, using the latest version of SCAPS-1D. The best solar-cell device from this series is obtained for the 20 nm top layer, with an efficiency of 16.3 % after anti­reflective coating. However, we observe a trend of decreasing open-circuit voltage for increasing top-layer thicknesses, and we do not find direct evidence that the lowering of the gallium concentration at the CIGS surface should generally be expected to improve the device performance. A simulated device with reduced bulk and interface defect levels achieves 20 % efficiency, but the trends concerning the CIS top layer remain the same.

  • 34.
    Schleussner, Sebastian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Linnarsson, Margareta
    Royal Institute of Technology, Stockholm.
    Zimmermann, Uwe
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wätjen, Timo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Development of gallium gradients in three‐ stageCu(In,Ga)Se2 co‐evaporation processes2012In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 20, no 3, p. 284-293Article in journal (Refereed)
    Abstract [en]

    We use secondary-ion mass spectrometry, X-ray diffraction and scanning electron microscopy to investigate the development over time of compositional gradients in Cu(In,Ga)Se2 thin films grown in three-stage co-evaporation processes and suggest a comprehensive model for the formation of the well-known ‘notch’ structure. The model takes into account the need for compensating Cu diffusion by movement of group-III ions in order to remain on the quasi-binary tie line and indicates that the mobilities of In and Ga ions differ. Cu diffuses towards the back in the second stage and towards the front in the third, and this is the driving force for the movement of In and Ga. The [Ga]/[In + Ga] ratio then increases in the direction of the respective Cu movement because In has a higher mobility at process conditions than has Ga. Interdiffusion of In and Ga can be considerable in the (In,Ga)2Se3 film of the first stage, but seems largely to cease in Cu(In,Ga)Se2 and shows no signs of being boosted by the presence of a Cu2Se layer.

  • 35.
    Schöldström, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zimmermann, Uwe
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Dynamic radiative properties of the Cu(In,Ga)Se2 layer during the co-evaporation process2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 5, p. 321-327Article in journal (Refereed)
    Abstract [en]

    A study of the wavelength-integrated emissivity has been performed on the optical stack CuxSe/Cu(In,Ga)Se2/Mo. Thewavelength interval used in the study was 2–20 µm, which covers 95% of the radiated heat from a black body heated to500°C. Substrate temperatures around 500°C are commonly used in production of Cu(In,Ga)Se2 thin films for solar cells.The integrated emissivity was obtained from directional reflectivity measurements of experimental samples with differentthicknesses of the CuxSe layers. It was subsequently compared to the emissivity from numerical simulations based onnewly obtained values of the refractive index values for Cu(In,Ga)Se2 and Cu x Se at these wavelengths. Good agreementwas found between the measured and simulated values. At a Cu(In,Ga)Se2 thickness of 1.8 µm and a Mo thickness of 400 nm, a maximum in the integrated emissivity was found for a CuxSe thickness of 30 nm. The results are valuable inputinto understanding the dynamics of the change in emissivity between Cu-rich Cu(In,Ga)Se2 with segregated CuxSe and Cu-poor single phase Cu(In,Ga)Se2 at temperatures around 500°C. In co-evaporation of Cu(In,Ga)Se2, this emissivity changeis often monitored and used as a process control (end-point detection).

  • 36.
    Scragg, Jonathan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ericson, Tove
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fontané, Xavier
    Catalonia Institute for Energy Research (IREC), C Jardins de les Dones de Negre, Sant Adrià del Besòs, Barcelona, Spanien.
    Izquierdo-Roca, Victor
    Catalonia Institute for Energy Research (IREC), C Jardins de les Dones de Negre, Sant Adrià del Besòs, Barcelona, Spanien.
    Pérez-Rodríguez, Alejandro
    Catalonia Institute for Energy Research (IREC), C Jardins de les Dones de Negre, Sant Adrià del Besòs, Barcelona, Spanien och Departament d'Electrònica, IN2UB, Universitat de Barcelona, Spanien.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rapid annealing of reactively sputtered precursors for Cu2ZnSnS4 solar cells2013In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 22, no 1, p. 10-17Article in journal (Refereed)
    Abstract [en]

    Cu2ZnSnS4 (CZTS) is a promising thin-film absorber material that presents some interesting challenges in fabrication when compared with Cu(In,Ga)Se2. We introduce a two-step process for fabrication of CZTS films, involving reactive sputtering of a Cu-Zn-Sn-S precursor followed by rapid annealing. X-ray diffraction and Raman measurements of the sputtered precursor suggest that it is in a disordered, metastable CZTS phase, similar to the high-temperature cubic modification reported for CZTS. A few minutes of annealing at 550 °C are sufficient to produce crystalline CZTS films with grain sizes in the micrometer range. The first reported device using this approach has an AM1.5 efficiency of 4.6%, with Jsc and Voc both appearing to be limited by interface recombination. 

  • 37. Siebentritt, Susanne
    et al.
    Igalson, Malgorzata
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Lany, Stephan
    The electronic structure of chalcopyrites-bands, point defects and grain boundaries2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 6, p. 390-410Article in journal (Refereed)
    Abstract [en]

    We summarize the progress made recently in understanding the electronic structure of chalcopyrites. New insights into the dispersion of valence and conduction band allow conclusions on the effective masses of charge carriers and their orientation dependence, which influences the transport in solar cell absorbers of different orientation. Native point defects are responsible for the doping and thus the band bending in solar cells. Results of optoelectronic defect spectroscopy are reviewed. Native defects are also the source for a number of metastabilities, which strongly affect the efficiency of solar cells. Recent theoretical findings relate these effects to the Se vacancy and the In-Cu antisite defect. Experimentally determined activation energies support these models. Absorbers in chalcopyrite solar cells are polycrystalline, which is only possible because of the benign character of the grain boundaries. This can be related to an unusual electronic structure of the GB.

  • 38.
    Sterner, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Malmström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Study on ALD In2S3/Cu(In,Ga)Se2 interface formation2005In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 13, no 3, p. 179-193Article in journal (Refereed)
    Abstract [en]

    The formation of the interface between In2S3 grown by atomic layer deposition (ALD) and co-evaporated Cu(In,Ga)Se2 (CIGS) has been studied by X-ray and UV photoelectron spectroscopy. The valence band offset at 160°C ALD substrate temperature was determined as −1·2±0·2 eV for CIGS deposited on soda-lime glass substrates and −1·4±0·2 eV when a Na barrier substrate was used. Wavelength dependent complex refractive index of In2S3 grown directly on glass was determined from inversion of reflectance and transmittance spectra. From these data, an indirect optical bandgap of 2·08±0·05 eV was deduced, independent of film thickness, of substrate temperature and of Na content. CIGS solar cells with ALD In2S3 buffer layers were fabricated. Highest device efficiency of 12·1% was obtained at a substrate temperature of 120°C. Using the bandgap obtained for In2S3 on glass and a 1·15±0·05 eV bandgap determined for the bulk of the CIGS absorber, the conduction band offset at the buffer interface was estimated as −0·25±0·2 eV (−0·45±0·2 eV) for Na-containing (Na-free) CIGS.

  • 39.
    Törndahl, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Coronel, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    The effect of Zn1-xMgxO buffer layer deposition temperature on Cu(In,Ga)Se2 solar cells: A study of the buffer/absorber interface2009In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 17, no 2, p. 115-125Article in journal (Refereed)
    Abstract [en]

    The effect of atomic layer deposition temperature of Zn1-xMgxO buffer   layers for Cu(In,Ga)Se-2 (CIGS) based solar cell devices is evaluated.   The Zn1-xMgxO films are grown using diethyl zinc, bis-cyclopentadienyl   magnesium and water as precursors in a temperature range of 105 to 180   C High efficiency devices are produced in the region front 105 up to   135 degrees C. At a Zn1-xMgxO deposition temperature of 120 C, a   maximum cell efficiency of 15.5% is reached by using a Zn1-xMgxO layer   with an x-value of 0.2 and a thickness of 140 inn. A significant drop   in cell efficiency due to large losses in open circuit voltage and fill   factor is observed for devices grown at temperatures above 150 C. No   differences in chemical composition, structure and morphology of the   samples are observed, except for the samples prepared at 105 and 120 C   that show elemental selenium present at the buffer/absorber interface.   The selenium at the interface does not lead to major degradation of   the,solar cell device efficiency. Instead, a decrease in Zn1-xMgxO   resistivity by more than one order of magnitude at growth temperatures   above 150 C may explain the degradation in solar cell performance. From   energy filtered transmission electron microscopy, the width of the   CIGS/Zn1-xMgxO chemical interface is found to be thinner than 10 not   without any areas of depletion for Cu, Se, Zn and O.

  • 40.
    Törndahl, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kessler, John
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Atomic layer deposition of Zn1-xMgxO buffer layers for Cu(In,Ga)Se2 solar cells2007In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 15, no 3, p. 225-235Article in journal (Refereed)
    Abstract [en]

    Fabrication of Zn1-xMgxO films by atomic layer deposition (ALD) has been studied for use as buffer layers in Cu(In,Ga)Se2 (CIGS)-based solar cell devices. The Zn1-xMgxO films were grown using diethyl zinc, bis-cyclopentadienyl magnesium and water as precursors in the temperature range from 105 to 180°C. Single-phase ZnO-like films were obtained for x < 0·2, followed by a two phase region of ZnO- and MgO-like structures for higher Mg concentrations. Increasing optical band gaps of up to above 3·8 eV were obtained for Zn1-xMgxO with increasing x. It was found that the composition of the Zn1-xMgxO films varied as an effect of deposition temperature as well as by increasing the relative amount of magnesium precursor pulses during film growth. Completely Cd-free CIGS-based solar cells devices with ALD-Zn1-xMgxO buffer layers were fabricated and showed efficiencies of up to 14·1%, which was higher than that of the CdS references.

  • 41.
    Vermang, Bart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wätjen, Jörn Timo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fjällström, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rostvall, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kotipalli, Ratan
    Henry, Fredric
    Flandre, Denis
    Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells2014In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 22, no 10, p. 1023-1029Article, review/survey (Refereed)
  • 42.
    Wallin, Erik
    et al.
    Solibro Research AB.
    Malm, Ulf
    Solibro Research AB.
    Jarmar, Tobias
    Solibro Research AB.
    Lundberg, Olle
    Solibro Reserach AB.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Solibro Research AB.
    World record Cu(In,Ga)Se2-based thin-film sub-module with 17.4 % efficiency2012In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 20, no 7, p. 851-854Article in journal (Refereed)
    Abstract [en]

    We report a new certified world-record efficiency for thin-film Cu(In,Ga)Se2-based photovoltaic sub-modules of 17.4%(aperture area). The record efficiency of the 16 cm2, monolithically integrated, sub-module has been independently confirmedby Fraunhofer ISE. The record device is the result of extensive co-optimization of all processing steps. Duringthe optimization process, strong focus has been put on the scalability of processes to cost-effective mass production, asreflected, for example, in Cu(In,Ga)Se2 deposition time and substrate temperature. Device manufacturing as well as resultsof electrical and material characterization is discussed.

  • 43.
    Xie, Zhibin
    et al.
    Department of Materials Science and Engineering, National University of Singapore.
    Midya, Anupam
    Department of Chemistry, National University of Singapore.
    Loh, Kian Ping
    Department of Chemistry, National University of Singapore.
    Adams, Stefan
    Department of Materials Science and Engineering, National University of Singapore.
    Blackwood, Daniel John
    Department of Materials Science and Engineering, National University of Singapore.
    Wang, John
    Department of Materials Science and Engineering, National University of Singapore.
    Zhang, Xuanjun
    Department of Chemistry, National University of Singapore.
    Chen, Zhikuan
    Institute of Materials Research & Engineering, 3 Research Link, Singapore.
    Highly efficient dye-sensitized solar cells using phenothiazine derivative organic dyes2010In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 18, no 8, p. 573-581Article in journal (Refereed)
    Abstract [en]

    Two novel organic dyes have been synthesized using electron rich phenothiazine as electron donors and oligothiophene vinylene as conjugation spacers. The two dyes (2E)-2-cyano-3-(5-(5-((E)-2-(10-(2-ethylhexyl)-10H-phenothiazin-7-yl)vinyl)thiophen-2-yl)thiophen-2-yl)acrylic acid (PTZ-1) and (2E)-3-(5-(5-(4,5-bis((E)-2-(10-(2-ethylhexyl)-10H-phenothiazin-3-yl)vinyl)thiophen-2-yl)thiophen-2-yl)thiophen-2-yl)-2-cyanoacrylic acid (PTZ-2) were fully characterized and employed in dye-sensitized solar cells (DSCs) to explore the effect of disubstituted donors on photovoltaic (PV) performance. The solar cells sensitized by the PTZ1 dye have a high IPCE plateau of 80% and achieve a short-circuit photocurrent density of 12.98 mA/cm2, an open-circuit voltage of 0.713 V, and a fill factor (ff) of 66.6%, corresponding to a conversion efficiency of 6.17% under AM 1.5 100 mW/cm2 illumination. The different performance of the solar cells based on the two dyes can be understood from the studies of the electron kinetics by electrochemical impedance spectroscopy (EIS). These investigations reveal that disubstituted donors in the organic sensitizers of three or more conjugation units deteriorate the PV performance due to enhanced recombination.

  • 44. Yang, L.
    et al.
    Mo, L.
    Okuno, Y.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Optimal design of ultra-broadband, omnidirectional, and polarization-insensitive amorphous silicon solar cells with a core-shell nanograting structure2013In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 21, no 5, p. 1077-1086Article in journal (Refereed)
    Abstract [en]

    We systematically investigated the optical behaviors of an amorphous silicon solar cell with a core-shell nanograting structure. The horizontally propagating Bloch waves and Surface Plasmon Polariton waves lead to significant absorption enhancements and consequently short-circuit current enhancements of this structure, compared with the conventional planar one. The perpendicular carrier collection makes this structure optically thick and electronically thin. An optimal design is achieved through full-field numerical simulation, and a physical explanation is given. Our numerical results show that this configuration has ultra-broadband, omnidirectional, and polarization-insensitive responses and has a great potential in photovoltaics.

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