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  • 1.
    Andaji-Garmaroudi, Zahra
    et al.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Abdi-Jalebi, Mojtaba
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England.;UCL, Inst Mat Discovery, Torrington Pl, London WC1E 7JE, England..
    Kosasih, Felix U.
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England..
    Doherty, Tiarnan
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Macpherson, Stuart
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Bowman, Alan R.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Ducati, Caterina
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England..
    Friend, Richard H.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Stranks, Samuel D.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England.;Univ Cambridge, Dept Chem Engn & Biotechnol, Philippa Fawcett Dr, Cambridge CB3 0AS, England..
    Elucidating and Mitigating Degradation Processes in Perovskite Light-Emitting Diodes2020In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 10, no 48, article id 2002676Article in journal (Refereed)
    Abstract [en]

    Halide perovskites have attracted substantial interest for their potential as disruptive display and lighting technologies. However, perovskite light-emitting diodes (PeLEDs) are still hindered by poor operational stability. A fundamental understanding of the degradation processes is lacking but will be key to mitigating these pathways. Here, a combination of in operando and ex situ measurements to monitor the performance degradation of (Cs(0.06)FA(0.79)MA(0.15))Pb(I0.85Br0.15)(3) PeLEDs over time is used. Through device, nanoscale cross-sectional chemical mapping, and optical spectroscopy measurements, it is revealed that the degraded performance arises from an irreversible accumulation of bromide content at one interface, which leads to barriers to injection of charge carriers and thus increased nonradiative recombination. This ionic segregation is impeded by passivating the perovskite films with potassium halides, which immobilizes the excess halide species. The passivated PeLEDs show enhanced external quantum efficiency (EQE) from 0.5% to 4.5% and, importantly, show significantly enhanced stability, with minimal performance roll-off even at high current densities (>200 mA cm(-2)). The decay half-life for the devices under continuous operation at peak EQE increases from <1 to approximate to 15 h through passivation, and approximate to 200 h under pulsed operation. The results provide generalized insight into degradation pathways in PeLEDs and highlight routes to overcome these challenges.

  • 2.
    Chareev, Dmitriy A.
    et al.
    Ural Fed Univ, Ekaterinburg 620002, Russia; Inst Expt Mineral, Chernogolovka 142432, Russia; Kazan Fed Univ, Kazan 420008, Russia.
    Evstigneeva, Polina
    Inst Geol Ore Deposits Petrog Mineral & Geochem, Moscow 119017, Russia.
    Phuyal, Dibya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Man, Gabriel J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Vasiliev, Alexander N.
    Ural Fed Univ, Ekaterinburg 620002, Russia; Lomonosov Moscow State Univ, Moscow 119991, Russia; Natl Res South Ural State Univ, Chelyabinsk 454080, Russia.
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Heidelberg Univ, Kirchhoff Inst Phys, D-69120 Heidelberg, Germany.
    Growth of Transition-Metal Dichalcogenides by Solvent Evaporation Technique2020In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 20, no 10, p. 6930-6938Article in journal (Refereed)
    Abstract [en]

    Due to their physical properties and potential applications in energy conversion and storage, transition-metal dichalcogenides (TMDs) have garnered substantial interest in recent years. Among this class of materials, TMDs based on molybdenum, tungsten, sulfur, and selenium are particularly attractive due to their semiconducting properties and the availability of bottom-up synthesis techniques. Here we report a method which yields high-quality crystals of transition-metal diselenide and ditelluride compounds (PtTe2, PdTe2, NiTe2, TaTe2, TiTe2, RuTe2, PtSe2, PdSe2, NbSe2, TiSe2, VSe2, ReSe2) from their solid solutions, via vapor deposition from a metal-saturated chalcogen melt. Additionally, we show the synthesis of rare-earth-metal polychalcogenides and NbS2 crystals using the aforementioned process. Most of the crystals obtained have a layered CdI2 structure. We have investigated the physical properties of selected crystals and compared them to state of the art findings reported in the literature. Remarkably, the charge density wave transition in 1T-TiSe2 and 2H-NbSe2 crystals is well-defined at TCDW ≈ 200 and 33 K, respectively. Angle-resolved photoelectron spectroscopy and electron diffraction are used to directly access the electronic and crystal structures of PtTe2 single crystals and yield state of the art measurements.

  • 3.
    Garcia Fernandez, Alberto
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Svanström, Sebastian
    Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, Condensed Matter Phys Energy Mat, Box 516, SE-75120 Uppsala, Sweden..
    Sterling, Cody M.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Gangan, Abhijeet
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Erbing, Axel
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Kamal, Chinnathambi
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, Madhya Pradesh, India.;Homi Bhabha Natl Inst, Training Sch Complex, Mumbai 400094, Maharashtra, India..
    Sloboda, Tamara
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kammlander, Birgit
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Man, Gabriel J.
    Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, Condensed Matter Phys Energy Mat, Box 516, SE-75120 Uppsala, Sweden..
    Rensmo, Håkan
    Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, Condensed Matter Phys Energy Mat, Box 516, SE-75120 Uppsala, Sweden..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Cappel, Ute B.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Experimental and Theoretical Core Level and Valence Band Analysis of Clean Perovskite Single Crystal Surfaces2022In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 18, no 13, article id 2106450Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the surface and interface properties of lead halide perovskites is of interest for several applications, in which these materials may be used. To develop this understanding, the study of clean crystalline surfaces can be an important stepping stone. In this work, the surface properties and electronic structure of two different perovskite single crystal compositions (MAPbI(3) and Cs(x)FA(1-)(x)PbI(3)) are investigated using synchrotron-based soft X-ray photoelectron spectroscopy (PES), molecular dynamics simulations, and density functional theory. The use of synchrotron-based soft X-ray PES enables high surface sensitivity and nondestructive depth-profiling. Core level and valence band spectra of the single crystals are presented. The authors find two carbon 1s contributions at the surface of MAPbI(3) and assign these to MA(+) ions in an MAI-terminated surface and to MA(+) ions below the surface. It is estimated that the surface is predominantly MAI-terminated but up to 30% of the surface can be PbI2-terminated. The results presented here can serve as reference spectra for photoelectron spectroscopy investigations of technologically relevant polycrystalline thin films, and the findings can be utilized to further optimize the design of device interfaces.

  • 4. García-Fernández, Alberto
    et al.
    Svanström, Sebastian
    Sterling, Cody M.
    Stockholm University, Faculty of Science, Department of Physics.
    Gangan, Abhijeet
    Stockholm University, Faculty of Science, Department of Physics.
    Erbing, Axel
    Stockholm University, Faculty of Science, Department of Physics.
    Kamal, Chinnathambi
    Stockholm University, Faculty of Science, Department of Physics. Raja Ramanna Centre for Advanced Technology, India; Homi Bhabha National Institute, India.
    Sloboda, Tamara
    Kammlander, Birgit
    Man, Gabriel J.
    Rensmo, Håkan
    Odelius, Michael
    Stockholm University, Faculty of Science, Department of Physics.
    Cappel, Ute B.
    Experimental and Theoretical Core Level and Valence Band Analysis of Clean Perovskite Single Crystal Surfaces2022In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 18, no 13, article id 2106450Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the surface and interface properties of lead halide perovskites is of interest for several applications, in which these materials may be used. To develop this understanding, the study of clean crystalline surfaces can be an important stepping stone. In this work, the surface properties and electronic structure of two different perovskite single crystal compositions (MAPbI3 and CsxFA1–xPbI3) are investigated using synchrotron-based soft X-ray photoelectron spectroscopy (PES), molecular dynamics simulations, and density functional theory. The use of synchrotron-based soft X-ray PES enables high surface sensitivity and nondestructive depth-profiling. Core level and valence band spectra of the single crystals are presented. The authors find two carbon 1s contributions at the surface of MAPbI3 and assign these to MA+ ions in an MAI-terminated surface and to MA+ ions below the surface. It is estimated that the surface is predominantly MAI-terminated but up to 30% of the surface can be PbI2-terminated. The results presented here can serve as reference spectra for photoelectron spectroscopy investigations of technologically relevant polycrystalline thin films, and the findings can be utilized to further optimize the design of device interfaces.

  • 5.
    García-Fernández, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Sterling, Cody M.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Gangan, Abhijeet
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Erbing, Axel
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Kamal, Chinnathambi
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, Madhya Pradesh, India.;Homi Bhabha Natl Inst, Training Sch Complex, Mumbai 400094, Maharashtra, India..
    Sloboda, Tamara
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Kammlander, Birgit
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Experimental and Theoretical Core Level and Valence Band Analysis of Clean Perovskite Single Crystal Surfaces2022In: Small : nano micro, Vol. 18, no 13, article id 2106450Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the surface and interface properties of lead halide perovskites is of interest for several applications, in which these materials may be used. To develop this understanding, the study of clean crystalline surfaces can be an important stepping stone. In this work, the surface properties and electronic structure of two different perovskite single crystal compositions (MAPbI(3) and Cs(x)FA(1-x)PbI(3)) are investigated using synchrotron-based soft X-ray photoelectron spectroscopy (PES), molecular dynamics simulations, and density functional theory. The use of synchrotron-based soft X-ray PES enables high surface sensitivity and nondestructive depth-profiling. Core level and valence band spectra of the single crystals are presented. The authors find two carbon 1s contributions at the surface of MAPbI(3) and assign these to MA(+) ions in an MAI-terminated surface and to MA(+) ions below the surface. It is estimated that the surface is predominantly MAI-terminated but up to 30% of the surface can be PbI2-terminated. The results presented here can serve as reference spectra for photoelectron spectroscopy investigations of technologically relevant polycrystalline thin films, and the findings can be utilized to further optimize the design of device interfaces.

    Download full text (pdf)
    fulltext
  • 6.
    Man, Gabriel J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. GJM Sci Consulting, Ft Lee, NJ 07024 USA..
    Kamal, Chinnathambi
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, India.;Homi Bhabha Natl Inst, Training Sch Complex, Mumbai 400094, Maharashtra, India..
    Kalinko, Aleksandr
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Phuyal, Dibya
    KTH Royal Inst Technol, Div Mat & Nano Phys, Dept Appl Phys, S-10691 Stockholm, Sweden..
    Acharya, Joydev
    Tata Inst Fundamental Res, Hyderabad 500046, India..
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Nayak, Pabitra K.
    Tata Inst Fundamental Res, Hyderabad 500046, India..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    A-site cation influence on the conduction band of lead bromide perovskites2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 3839Article in journal (Refereed)
    Abstract [en]

    Hot carrier solar cells hold promise for exceeding the Shockley-Queisser limit. Slow hot carrier cooling is one of the most intriguing properties of lead halide perovskites and distinguishes this class of materials from competing materials used in solar cells. Here we use the element selectivity of high-resolution X-ray spectroscopy and density functional theory to uncover a previously hidden feature in the conduction band states, the sigma-pi energy splitting, and find that it is strongly influenced by the strength of electronic coupling between the A-cation and bromide-lead sublattice. Our finding provides an alternative mechanism to the commonly discussed polaronic screening and hot phonon bottleneck carrier cooling mechanisms. Our work emphasizes the optoelectronic role of the A-cation, provides a comprehensive view of A-cation effects in the crystal and electronic structures, and outlines a broadly applicable spectroscopic approach for assessing the impact of chemical alterations of the A-cation on perovskite electronic structure. The A-cation influence on the mechanism of slow hot carrier cooling in perovskites is controversial. Here, Man et al. resolve a debated issue regarding A-cation influence on the electronic structure of lead halide perovskites.

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    FULLTEXT01
  • 7.
    Man, Gabriel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Condensed Matter Phys Energy Mat, Div Xray Photon Sci, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden..
    Sterling, Cody M.
    Stockholm Univ, Dept Phys, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden..
    Kamal, Chinnathambi
    Stockholm Univ, Dept Phys, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, India..
    Simonov, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Condensed Matter Phys Energy Mat, Div Xray Photon Sci, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden.;Swerim AB, S-16407 Stockholm, Sweden..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Condensed Matter Phys Energy Mat, Div Xray Photon Sci, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden..
    Acharya, Joydev
    Tata Inst Fundamental Res, TIFR Ctr Interdisciplinary Sci, 36-P Gopanpally Village, Hyderabad 500046, India..
    Johansson, Fredrik O. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Condensed Matter Phys Energy Mat, Div Xray Photon Sci, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden..
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Huthwelker, Thomas
    Paul Scherrer Inst, WLGA 212,Forschungsstr 111, CH-5232 Villigen, Switzerland..
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Condensed Matter Phys Energy Mat, Div Xray Photon Sci, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden..
    Nayak, Pabitra K.
    Tata Inst Fundamental Res, TIFR Ctr Interdisciplinary Sci, 36-P Gopanpally Village, Hyderabad 500046, India..
    Odelius, Michael
    Stockholm Univ, Dept Phys, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Condensed Matter Phys Energy Mat, Div Xray Photon Sci, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden..
    Electronic coupling between the unoccupied states of the organic and inorganic sublattices of methylammonium lead iodide: A hybrid organic-inorganic perovskite single crystal2021In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 104, no 4, article id L041302Article in journal (Refereed)
    Abstract [en]

    Organic-inorganic halide perovskites have been intensively reinvestigated due to their applications, yet the optoelectronic function of the organic cation remains unclear. Through organic-selective resonant Auger electron spectroscopy measurements on well-defined single-crystal surfaces, we find evidence for electronic coupling in the unoccupied states between the organic and inorganic sublattices of the prototypical hybrid perovskite, which is contrary to the notion based on previous studies that the organic cation is electronically inert. The coupling is relevant for electron dynamics in the material and for understanding optoelectronic functionality.

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    FULLTEXT01
  • 8.
    Phuyal, Dibya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. KTH Royal Inst Technol, Dept Appl Phys, Div Mat & Nano Phys, SE-10691 Stockholm, Sweden..
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Panda, Swarup K.
    Bennett Univ, Dept Phys, Greater Noida 201310, Uttar Pradesh, India..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Simonov, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Simonelli, Laura
    CELLS ALBA Synchrotron, E-08290 Barcelona, Spain..
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Uppsala Univ, Dept Phys, Div Mol & Condensed Matter Phys, SE-75121 Uppsala, Sweden..
    Nonlocal Interactions in the Double Perovskite Sr2FeMoO6 from Core-Level X-ray Spectroscopy2021In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 125, no 20, p. 11249-11256Article in journal (Refereed)
    Abstract [en]

    The valence electronic structure of the half-metallic double perovskite Sr2FeMoO6 forms from a strongly hybridized band in the spin-down channel of Fe 3d and Mo 4d states that provides metallic conductivity and a gapped spin-up channel. The ground-state description has previously been explored in terms of many-body interactions where local and nonlocal interactions produce states with a combination of a charge-transfer configuration and intersite charge fluctuations. Here, we provide a qualitative understanding on nonlocal effects in Sr2FeMoO6 using a combination of core-level X-ray spectroscopies, specifically X-ray absorption, emission, and photoelectron spectroscopies. Our spectroscopic data indicate intersite Fe 4p-O 2p-Mo 4d interactions to be the origin of these nonlocalized transitions. Close to the Fermi level, this interaction is dominated by Mo 4d-O 2p character. When our data are compared against first-principles electronic structure calculations, we conclude that a full understanding of the nature of these states requires a spin-resolved description of the hybridization functions and that the nonlocal screening occurs predominantly through hybridization in the minority spin channel of the Mo 4d bands.

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    FULLTEXT01
  • 9.
    Sterling, Cody M.
    et al.
    Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden.
    Kamal, Chinnathambi
    Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden; Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, Madhya Pradesh, India.
    Man, Gabriel J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Nayak, Pabitra K.
    Tata Inst Fundamental Res, TIFR Ctr Interdisciplinary Sci, Hyderabad 500046, India.
    Simonov, Konstantin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    García-Fernández, Alberto
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Huthwelker, Thomas
    Paul Scherrer Inst, Swiss Light Source, CH-5232 Villigen, Switzerland.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Butorin, Sergei M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden.
    Sensitivity of Nitrogen K-Edge X-ray Absorption to Halide Substitution and Thermal Fluctuations in Methylammonium Lead-Halide Perovskites2021In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 125, no 15, p. 8360-8368Article in journal (Refereed)
    Abstract [en]

    The performance of hybrid perovskite materials in solar cells crucially depends on their electronic properties, and it is important to investigate contributions to the total electronic structure from specific components in the material. In a combined theoretical and experimental study of CH3NH3PbI3—methylammonium lead triiodide (MAPI)—and its bromide cousin CH3NH3PbBr3 (MAPB), we analyze nitrogen K-edge (N 1s-to-2p*) X-ray absorption (XA) spectra measured in MAPI and MAPB single crystals. This permits comparison of spectral features to the local character of unoccupied molecular orbitals on the CH3NH3+ (MA+) counterions and allows us to investigate how thermal fluctuations, hydrogen bonding, and halide-ion substitution influence the XA spectra as a measure of the local electronic structure. In agreement with the experiment, the simulated spectra for MAPI and MAPB show close similarity, except that the MAPB spectral features are blue-shifted by +0.31 eV. The shift is shown to arise from the intrinsic difference in the electronic structure of the two halide atoms rather than from structural differences between the materials. In addition, from the spectral sampling analysis of molecular dynamics simulations, clear correlations between geometric descriptors (N–C, N–H, and H···I/Br distances) and spectral features are identified and used to explain the spectral shapes.

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  • 10.
    Svanström, Sebastian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    García Fernández, Alberto
    Kungliga Tekniska Högskolan.
    Jacobsson, T Jesper
    Bidermane, Ieva
    Leitner, Torsten
    Sloboda, Tamara
    Kungliga Tekniska Högskolan.
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B
    Kungliga Tekniska Högskolan.
    The complex degradation mechanism of copper electrodes on lead halide perovskiteIn: ACS Materials Science Au, E-ISSN 2694-2461Article in journal (Other academic)
  • 11.
    Svanström, Sebastian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    García-Fernández, Alberto
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Jacobsson, T. Jesper
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Young Investigator Grp Hybrid Mat Format & Scalin, D-12489 Berlin, Germany..
    Bidermane, Ieva
    Uppsala Berlin Joint Lab Next Generat Photoelectr, D-12489 Berlin, Germany..
    Leitner, Torsten
    Uppsala Berlin Joint Lab Next Generat Photoelectr, D-12489 Berlin, Germany..
    Sloboda, Tamara
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    The Complex Degradation Mechanism of Copper Electrodes on Lead Halide Perovskites2022In: ACS Materials Science Au, E-ISSN 2694-2461, Vol. 2, no 3, p. 301-312Article in journal (Refereed)
    Abstract [en]

    Lead halide perovskitesolar cells have reached power conversionefficiencies during the past few years that rival those of crystallinesilicon solar cells, and there is a concentrated effort to commercializethem. The use of gold electrodes, the current standard, is prohibitivelycostly for commercial application. Copper is a promising low-costelectrode material that has shown good stability in perovskite solarcells with selective contacts. Furthermore, it has the potential tobe self-passivating through the formation of CuI, a copper salt whichis also used as a hole selective material. Based on these opportunities,we investigated the interface reactions between lead halide perovskitesand copper in this work. Specifically, copper was deposited on theperovskite surface, and the reactions were followed in detail usingsynchrotron-based and in-house photoelectron spectroscopy. The resultsshow a rich interfacial chemistry with reactions starting upon depositionand, with the exposure to oxygen and moisture, progress over manyweeks, resulting in significant degradation of both the copper andthe perovskite. The degradation results not only in the formationof CuI, as expected, but also in the formation of two previously unreporteddegradation products. The hope is that a deeper understanding of theseprocesses will aid in the design of corrosion-resistant copper-basedelectrodes.

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  • 12.
    Wu, Hua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. ilin Univ, State Key Lab Integrated Optoelect, Changchun 130012, Jilin, Peoples R China;Jilin Univ, Coll Elect Sci & Engn, Changchun 130012, Jilin, Peoples R China.
    Zhu, Huimin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Erbing, Axel
    Stockholm Univ, Alballova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.
    Johansson, Malin B
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Odelius, Michael
    Stockholm Univ, Alballova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bandgap Tuning of Silver Bismuth Iodide via Controllable Bromide Substitution for Improved Photovoltaic Performance2019In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, no 8, p. 5356-5362Article in journal (Refereed)
    Abstract [en]

    In this work, silver-bismuth-halide thin films, exhibiting low toxicity and good stability, were explored systemically by gradually substituting iodide, I, with bromide, Br, in the AgBi2I7 system. It was found that the optical bandgap can be tuned by varying the I/Br ratio. Moreover, the film quality was improved when introducing a small amount of Br. The solar cell was demonstrated to be more stable at ambient conditions and most efficient when incorporating 10% Br, as a result of decreased recombination originating from the increased grain size. Thus, replacing a small amount of I with Br was beneficial for photovoltaic performance.

  • 13.
    Zhu, Huimin
    et al.
    Uppsala Univ, Dept Chem, Angstrom Lab, Div Phys Chem, S-75120 Uppsala, Sweden..
    Erbing, Axel
    Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden..
    Wu, Hua
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Jilin Univ, State Key Lab Integrated Optoelect, Changchun 130012, Peoples R China.;Jilin Univ, Coll Elect Sci & Engn, Changchun 130012, Peoples R China..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Kamal, Chinnathambi
    Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, India..
    Johansson, Malin B
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Odelius, Michael
    Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden..
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Tuning the Bandgap in Silver Bismuth Iodide Materials by Partly Substituting Bismuth with Antimony for Improved Solar Cell Performance2020In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 3, no 8, p. 7372-7382Article in journal (Refereed)
    Abstract [en]

    Silver bismuth iodide (Ag-Bi-I) light absorbers are interesting candidates as lead-free and low-toxic metal-halide materials for solar cell applications. In this work, the partial exchange of bismuth, Bi, with antimony, Sb, is investigated in samples prepared from a solution targeting stoichiometry AgBi2I7. Samples with a gradually increased exchange of Bi by Sb are prepared and light absorption measurements show that the absorption edge is gradually blue-shifted with increasing the amount of Sb. This trend in the shift in combination with the X-ray diffraction and X-ray photoelectron spectroscopy measurements, suggest that new materials with a mixture of Sb and Bi are formed. The density functional theory based electronic structure calculations reproduce the trend observed in the experiments when including spin-orbit coupling, which indicates the importance of relativistic effects in these materials. X-ray photoelectron spectroscopy is used to characterize the materials, and confirms the exchange of Bi to Sb in the samples. When Sb is included in the material, the grain size changes between 50 and 200 nm and the solar cell performance also changes. An optimal power conversion efficiency with excellent reproducibility and stability is obtained for a solar cell with the ratio of Sb/Bi equal to 3.

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