Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Quantum Dot Solar Cells: Towards Environmentally Friendly Materials
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To decrease the world’s energy dependence on fossil fuels, energy production and specifically electricity production needs to shift to more sustainable alternatives. One such alternative is solar cells as they directly convert energy emitted from the sun into electricity. Silicon and thin film solar cells which are commercialized today are either expensive to make and rigid, or utilizes rare and toxic materials. This has resulted in an increase in the field of solar cell research to find cheaper alternatives which are also based on abundant materials.

Colloidal quantum dot (CQD) solar cells are third generation solar cells which has received much focus in the last decade due to the property of the quantum confinement effects. This makes it possible to increase the band gap by decreasing the size of the crystallites.CQDs made of PbS were in this thesis developed for high PCE (power conversion efficiency), low weight and flexible CQD solar cells. By applying the PbS CQDs on flexible and durable substrates, light weight solar cells with a high power-per-weight of 15.2 W g-1 value were accomplished. Other PbS CQD solar cells were covered and passivated by a mid-high band gap perovskite semiconductor with good lattice matching to facilitate improved stability and PCE, with the latter reaching 10.7 %.

By shifting the focus towards more low-toxic and more environmentally friendly materials, materials such as PbS could be phased out. In this thesis, Ag2S and AgBiS2 were investigated as alternatives. By utilizing a heat-up synthesis method for the production of Ag2S CQDs, a proof-of-concept PCE of 0.34 % was accomplished for solar cells based on these CQDs. To improve the PCE, a hot-injection method was utilized to produce Ag2S CQDs with a surface better suited for solar cell applications. This resulted in an improved PCE of 2.2 %. In a final study, AgBiS2 CQDs were investigated by changing the composition of the precursor ratio Ag:Bi:S. The final composition was linearly dependent on the Ag precursor concentration. The best device with the highest PCE had a composition close to the stoichiometric ratio of 1:1:2 which was achieved by a precursor composition of 0.72:0.9:1. This resulted in a PCE of 3.3 %.

The understanding of PbS CQD solar cells and how they can be further improved and ap-plying the relevant information and research to low-toxic alternatives is necessary for the im-provements of these more environmentally friendly CQD materials in solar cell applications.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. , p. 108
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1878
Keywords [en]
Quantum dots, Nano-crystals, Energy conversion, Solar cells, Quantum dot solar cells, Low toxicity, Silver Sulfide, Silver Bismuth Sulfide, Lead Sulfide
National Category
Physical Chemistry
Research subject
Chemistry with specialization in Physical Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-393426ISBN: 978-91-513-0811-1 (print)OAI: oai:DiVA.org:uu-393426DiVA, id: diva2:1353234
Public defence
2019-11-08, Häggsalen, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2019-10-16 Created: 2019-09-21 Last updated: 2019-11-07
List of papers
1. Extremely lightweight and ultra-flexible infrared light-converting quantum dot solar cells with high power-per-weight output using a solution-processed bending durable silver nanowire-based electrode
Open this publication in new window or tab >>Extremely lightweight and ultra-flexible infrared light-converting quantum dot solar cells with high power-per-weight output using a solution-processed bending durable silver nanowire-based electrode
Show others...
2018 (English)In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 11, no 2, p. 354-364Article in journal (Refereed) Published
Abstract [en]

Lightweight and flexible solar cells are highly interesting materials for use in new applications, such as spacecraft, aircraft and personal pack load. PbS colloidal quantum dots (CQDs) exhibit a broad and strong light absorption spectrum covering the ultraviolet-visible-near infrared region, allowing for incorporation of very thin CQD films into solar cells with high power conversion efficiency (PCE) from solar light to electricity. Herein, we report an extremely lightweight and ultra-flexible CQD solar cell constructed on a polyethylene naphthalate substrate with a thickness of 1.3 mu m. A solution-processed Ag nanowire network with excellent mechanical, optical and electrical properties was prepared as the front-electrode in the solar cell. The thickness of the complete CQD solar cell is less than 2 mm, and similar to 10% PCE with a weight of 6.5 g m(-2) is achieved, resulting in a power-per-weight output of 15.2 W g(-1). The flexible solar cell possesses durable mechanical properties and maintains high-level photovoltaic performance under extreme deformation and after repeated compression-stretching deformation. Moreover, the flexible CQD solar cell shows impressive stability both under continuous illumination and after storage under ambient conditions. These results reveal that solution-processed CQDs are compatible with an ultra-flexible substrate for the construction of ultra-lightweight infrared light-converting CQD solar cells with possibilities for new exciting solar energy applications.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-349844 (URN)10.1039/c7ee02772a (DOI)000425283400013 ()
Funder
Göran Gustafsson Foundation for Research in Natural Sciences and MedicineSwedish Energy AgencySwedish Research Council FormasÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research CouncilStiftelsen Olle Engkvist Byggmästare
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2019-09-21Bibliographically approved
2. Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells
Open this publication in new window or tab >>Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells
Show others...
2018 (English)In: Advanced Energy Materials, ISSN 1614-6832, Vol. 8, no 6, article id 1702049Article in journal (Refereed) Published
Abstract [en]

Solution-processed colloidal quantum dot (CQD) solar cells harvesting the infrared part of the solar spectrum are especially interesting for future use in semitransparent windows or multilayer solar cells. To improve the device power conversion efficiency (PCE) and stability of the solar cells, surface passivation of the quantum dots is vital in the research of CQD solar cells. Herein, inorganic CsPbI3 perovskite (CsPbI3-P) coating on PbS CQDs with a low-temperature, solution-processed approach is reported. The PbS CQD solar cell with CsPbI3-P coating gives a high PCE of 10.5% and exhibits remarkable stability both under long-term constant illumination and storage under ambient conditions. Detailed characterization and analysis reveal improved passivation of the PbS CQDs with the CsPbI3-P coating, and the results suggest that the lattice coherence between CsPbI3-P and PbS results in epitaxial induced growth of the CsPbI3-P coating. The improved passivation significantly diminishes the sub-bandgap trap-state assisted recombination, leading to improved charge collection and therefore higher photovoltaic performance. This work therefore provides important insight to improve the CQD passivation by coating with an inorganic perovskite ligand for photovoltaics or other optoelectronic applications.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
charge recombination, inorganic perovskite, quantum dots, solar cells, surface passivation
National Category
Physical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348982 (URN)10.1002/aenm.201702049 (DOI)000426152400017 ()
Funder
Swedish Energy AgencySwedish Research CouncilSwedish Research Council Formas
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2019-09-26
3. Solution-Processed Environmentally Friendly Ag2S Colloidal Quantum Dot Solar Cells with Broad Spectral Absorption
Open this publication in new window or tab >>Solution-Processed Environmentally Friendly Ag2S Colloidal Quantum Dot Solar Cells with Broad Spectral Absorption
2017 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 7, no 10, article id 1020Article in journal (Refereed) Published
Abstract [en]

A facile heat-up synthesis route is used to synthesize environmentally friendly Ag2S colloidal quantum dots (CQDs) that are applied as light absorbing material in solid state p-i-n junction solar cell devices. The as-synthesized Ag2S CQDs have an average size of around 3.5 nm and exhibit broad light absorption covering ultraviolet, visible, and near infrared wavelength regions. The solar cell devices are constructed with a device architecture of FTO/TiO2/Ag2S CQDs/hole transport material (HTM) /Au using a solution-processed approach. Different HTMs, N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl)-9,9′-spirobi(9H-fluorene)-2,2′,7,7′ tetramine (spiro-OMeTAD), poly(3-hexylthiophene-2,5-diyl) (P3HT), and poly((2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl)-2,5-thiophenediyl) TQ1 are studied for maximizing the device photovoltaic performance. The solar cell device with P3HT as a hole transport material gives the highest performance and the solar cell exhibit broad spectral absorption. These results indicate that Ag2S CQD have high potential for utilization as environmentally friendly light absorbing materials for solar cell application and that the hole transport material is critical to maximize the solar cell photovoltaic performance.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-337578 (URN)10.3390/app7101020 (DOI)000414457800058 ()
Funder
Swedish Energy AgencyGöran Gustafsson Foundation for Research in Natural Sciences and MedicineÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research Council FormasSwedish Research Council
Available from: 2018-01-02 Created: 2018-01-02 Last updated: 2019-09-21Bibliographically approved
4. Hot-Injection Synthesized Ag2S Quantum Dots with Broad Light Absorption and High Stability for Solar Cell Applications
Open this publication in new window or tab >>Hot-Injection Synthesized Ag2S Quantum Dots with Broad Light Absorption and High Stability for Solar Cell Applications
2018 (English)In: CHEMNANOMAT, ISSN 2199-692X, Vol. 4, no 12, p. 1223-1230Article in journal (Refereed) Published
Abstract [en]

A hot-injection synthesis method was used to synthesize low-toxicity Ag2S colloidal quantum dots (CQDs) with strong and broad light absorption as an ultra-thin photo-absorber in CQD heterojunction solar cells. By using iodide and sulfur linkers it was possible to accomplish efficient charge carrier extraction, resulting in a high photocurrent due to the broad absorption spectrum. Transient photovoltage decay measurements were used to obtain information about trap states in the CQDs and the effect on the lifetime of the photoinduced carriers. The devices show very promising stability under constant long-term illumination and they are stable under ambient storage conditions with low losses to the performance over a period of over two months. These results show that Ag2S CQDs have high potential within solar cell applications, and point the direction for further improvements.

Keywords
energy conversion, hot-injection, quantum dots, silver sulfide, solar cells
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-372703 (URN)10.1002/cnma.201800263 (DOI)000452048600005 ()
Funder
Swedish Energy AgencySwedish Research Council FormasSwedish Research CouncilÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-09-21Bibliographically approved
5. Tuning Size and Composition in Cubic AgBiS2 CQDs for Solar Cells
Open this publication in new window or tab >>Tuning Size and Composition in Cubic AgBiS2 CQDs for Solar Cells
(English)Manuscript (preprint) (Other academic)
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-393425 (URN)
Available from: 2019-09-21 Created: 2019-09-21 Last updated: 2019-10-01

Open Access in DiVA

fulltext(3507 kB)74 downloads
File information
File name FULLTEXT01.pdfFile size 3507 kBChecksum SHA-512
9a05a610233b10519f0de9c31b6eef35eeb71898b4c0c48cb9303f4659e1b6999f9be55cbdfec8e0e4bcfd69d6d7f937cce6ca34743e11f653c263af46ae0f84
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Öberg, Viktor A.
By organisation
Physical Chemistry
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 74 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 204 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf