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Ericsson, Leif
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Publications (10 of 25) Show all publications
Blazinic, V., Ericsson, L., Levine, I., Hansson, R., Opitz, A. & Moons, E. (2019). Impact of intentional photo-oxidation of a donor polymer and PC70BM on solar cell performance. Physical Chemistry, Chemical Physics - PCCP
Open this publication in new window or tab >>Impact of intentional photo-oxidation of a donor polymer and PC70BM on solar cell performance
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2019 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084Article in journal (Refereed) Epub ahead of print
Abstract [en]

A short lifetime is the main factor hindering the wider implementation of low-cost organic photovoltaics in large-area and outdoor applications. Ingress of oxygen and water vapour through non-ideal encapsulation layers is a known cause of degradation for polymer/fullerene based solar cells. To better understand the origin of this performance degradation, we study the effect of intentional exposure of the photo-active layer to simulated sunlight (AM1.5) in air both on the solar cell performance and on the molecular semiconductor materials. Cathode-free thin films of a blend of the electron donor polymer poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) and the electron acceptor fullerene derivative [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) were exposed to simulated sunlight in air. Fourier-transform infrared spectra demonstrate the formation of carbonyl photo-oxidation products in the blend films, as well as in the pristine polymer and fullerene films. Solar cells prepared with photo-oxidized active layers show increasingly degraded electrical performance (lower short circuit current, open circuit voltage and fill factor) with increasing exposure time. The increased diode ideality factor indicates that trap-assisted recombination hinders device operation after exposure. The external quantum efficiency decreases drastically with increasing exposure time over the whole photon energy range, while the UV-vis absorption spectra of the blend films only show a mild photo-induced bleaching. This demonstrates that not only the photo-induced degradation of the solar cell performance is not predominantly caused by the loss in light absorption, but charge transport and collection are also hampered. This is explained by the fact that photo-oxidation of PC70BM causes bonds in its conjugated cage to break, as evidenced by the decreased ∏* intensity in C1s-NEXAFS spectra of PC70BM films. This degradation of unoccupied states of PC70BM will hinder the transport of photo-generated electrons to the electrode. Surface photovoltage spectroscopy gives direct evidence for gap states at the surface of a PC70BM film, formed after 2 hours of exposure and resulting in upward band bending at the PC70BM/air surface. These observations indicate that the photo-oxidation of PC70BM is likely to be the main cause of the performance degradation observed when the photoactive layer of a TQ1:PC70BM solar cell is intentionally exposed to light in air.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-75110 (URN)10.1039/C9CP04384E (DOI)
Funder
Swedish Energy Agency, 38327-1
Available from: 2019-10-07 Created: 2019-10-07 Last updated: 2019-10-11Bibliographically approved
van Stam, J., Ericsson, L., Deribew, D. & Moons, E. (2018). Morphology in Dip-Coated Blend Films for Photovoltaics Studied by UV/VIS Absorption and Fluorescence Spectroscopy. In: S. Reineke, K. Vandewal (Ed.), Organic Electronics and Photonics: Fundamentals and Devices. Paper presented at Conference on Organic Electronics and Photonics - Fundamentals and Devices, APR 24-26, 2018, Strasbourg, FRANCE. SPIE-INT SOC OPTICAL ENGINEERING, Article ID UNSP 106870A.
Open this publication in new window or tab >>Morphology in Dip-Coated Blend Films for Photovoltaics Studied by UV/VIS Absorption and Fluorescence Spectroscopy
2018 (English)In: Organic Electronics and Photonics: Fundamentals and Devices / [ed] S. Reineke, K. Vandewal, SPIE-INT SOC OPTICAL ENGINEERING , 2018, article id UNSP 106870AConference paper, Published paper (Refereed)
Abstract [en]

Blend thin films, prepared by dip-coating, of polyfluorene (F8 or PFO), acting as an electron donor, and [6,6]-phenyl-C-61-butyric acid methyl ester (PC60BM), acting as the electron acceptor, have been characterized by UV/VIS absorption spectroscopy, static and dynamic fluorescence, and atomic force microscopy. Four different solvents were used for the film preparation; the monohalogenated fluorobenzene and chlorobenzene and their dihalogenated counterparts o-difluorobenzene and o-dichlorobenzene, respectively. Fluid mechanics calculations were used to determine the withdrawal speed for each solvent, in order to prepare wet films of comparable thicknesses. The resulting dry films were also of similar thicknesses. It was found that the choice of solvent influences the ability for F8 to form its beta-phase.

Place, publisher, year, edition, pages
SPIE-INT SOC OPTICAL ENGINEERING, 2018
Series
Proceedings of SPIE, ISSN 0277-786X ; 10687
National Category
Physical Sciences Materials Engineering Chemical Sciences
Research subject
Physics; Chemistry
Identifiers
urn:nbn:se:kau:diva-70966 (URN)10.1117/12.2306857 (DOI)000453618300001 ()978-1-5106-1901-2 (ISBN)
Conference
Conference on Organic Electronics and Photonics - Fundamentals and Devices, APR 24-26, 2018, Strasbourg, FRANCE
Available from: 2019-02-07 Created: 2019-02-07 Last updated: 2019-06-14Bibliographically approved
Blazinic, V., Ericsson, L., Muntean, S. A. & Moons, E. (2018). Photo-degradation in air of spin-coated PC60BM and PC70BM films. Synthetic metals, 241, 26-30
Open this publication in new window or tab >>Photo-degradation in air of spin-coated PC60BM and PC70BM films
2018 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 241, p. 26-30Article in journal (Refereed) Published
Abstract [en]

The fullerene derivatives PC60BM and PC70BM are widely used as electron accepting components in the active layer of polymer solar cells. Here we compare their photochemical stability by exposing thin films of PC60BM and PC70BM to simulated sunlight in ambient air for up to 47 h, and study changes in their UV–vis and FT-IR spectra. We quantify the photo-degradation by tracking the development of oxidation products in the transmission FT-IR spectra. Results indicate that PC60BM photodegrades faster than PC70BM. The rate of photo-oxidation of the thin films is dependent on the rate of oxygen diffusion in to the film and on the photo-oxidation rate of a single molecule. Both factors are dependent on the nature of the fullerene cage. The faster photo-oxidation of PC60BM than of PC70BM is in agreement with its slightly lower density and its higher reactivity. The use of PC70BM in solar cells is advantageous not only because of its absorption spectrum, but also because of its higher stability.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Fullerene derivatives, Photo-oxidation, UV-vis spectroscopy, IR spectroscopy
National Category
Condensed Matter Physics
Research subject
Materials Science
Identifiers
urn:nbn:se:kau:diva-66953 (URN)10.1016/j.synthmet.2018.03.021 (DOI)
Available from: 2018-04-09 Created: 2018-04-09 Last updated: 2019-10-08Bibliographically approved
Farinhas, J., Oliveira, R., Hansson, R., Ericsson, L., Moons, E., Morgado, J. & Charas, A. (2017). Efficient ternary organic solar cells based on immiscible blends. Organic electronics, 41, 130-136
Open this publication in new window or tab >>Efficient ternary organic solar cells based on immiscible blends
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2017 (English)In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 41, p. 130-136Article in journal (Refereed) Published
Abstract [en]

Organic photovoltaic cells based on ternary blends of materials with complementary properties represent an approach to improve the photon-absorption and/or charge transport within the devices. However, the more complex nature of the ternary system, i.e. in diversity of materials' properties and morphological features, complicates the understanding of the processes behind such optimizations. Here, organic photovoltaic cells with wider absorption spectrum composed of two electron-donor polymers, F8T2, poly(9,9-dioctylfluorene-alt-bithiophene), and PTB7, poly([4,8-bis[(2'-ethylhexyl) oxy] benzo[1,2-b: 4,5-b'] dithiophene-2,6-diyl][3-fluoro-2-[(2'-ethylhexyl) carbonyl] thieno[3,4-b] thiophenediyl]), mixed with [6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM) are investigated. We demonstrate an improvement of 25% in power conversion efficiency in comparison with the most efficient binary blend control devices. The active layers of these ternary cells exhibit gross phase separation, as determined by Atomic Force Microscopy (AFM) and Synchrotron-based Scanning Transmission X-ray Microscopy (STXM).

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Polymer solar cells, Photovoltaics, Ternary blend, Morphology, High efficiency
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-62620 (URN)10.1016/j.orgel.2016.12.009 (DOI)000390586300017 ()
Available from: 2017-08-10 Created: 2017-08-10 Last updated: 2019-09-19Bibliographically approved
Chavhan, S. D., Hansson, R., Ericsson, L., Beyer, P., Hofmann, A., Brütting, W., . . . Moons, E. (2017). Low temperature processed NiOx hole transport layers for efficient polymer solar cells. Organic electronics, 44, 59-66
Open this publication in new window or tab >>Low temperature processed NiOx hole transport layers for efficient polymer solar cells
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2017 (English)In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 44, p. 59-66Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
OPV Nickel oxide Hole injection layer UV-ozone Kelvin probe XPS
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-47258 (URN)10.1016/j.orgel.2017.01.040 (DOI)000397441800009 ()
Funder
Swedish Energy Agency, 38327-2Swedish Research Council, 2015-03778Göran Gustafsson Foundation for Research in Natural Sciences and Medicine
Available from: 2016-11-23 Created: 2016-11-23 Last updated: 2019-09-19Bibliographically approved
Hansson, R., Ericsson, L., Holmes, N. P., Blazinic, V., Dastoor, P. & Moons, E. (2017). Opportunities and challenges in probing local composition of organic material blends for photovoltaics. Journal of Materials Research, 32(10), 1982-1992
Open this publication in new window or tab >>Opportunities and challenges in probing local composition of organic material blends for photovoltaics
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2017 (English)In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 32, no 10, p. 1982-1992Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Materials Research Society, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kau:diva-47259 (URN)10.1557/jmr.2017.7 (DOI)000402284600014 ()
Funder
Swedish Energy Agency, 38327-1Swedish Research Council, 2015-03778Göran Gustafsson Foundation for Research in Natural Sciences and Medicine
Available from: 2016-11-23 Created: 2016-11-23 Last updated: 2018-01-05Bibliographically approved
Hansson, R., Lindqvist, C., Ericsson, L., Opitz, A., Wang, E. & Moons, E. (2016). Photodegradation in air of the active layer components in a thiophene-quinoxaline copolymer:fullerene solar cell. Physical Chemistry, Chemical Physics - PCCP, 18(16), 11132-11138
Open this publication in new window or tab >>Photodegradation in air of the active layer components in a thiophene-quinoxaline copolymer:fullerene solar cell
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2016 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 16, p. 11132-11138Article in journal (Refereed) Published
Abstract [en]

We have studied the photo-degradation in air of a blend of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), and how the photo-degradation affects the solar cell performance. Using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, changes to the electronic structure of TQ1 and PCBM caused by illumination in ambient air are investigated and compared between the pristine materials and the blend. The NEXAFS spectra show that the unoccupied molecular orbitals of TQ1 are not significantly changed by the exposure of pristine TQ1 to light in air, whereas those of PCBM are severely affected as a result of photo-induced degradation of PCBM. Furthermore, the photo-degradation of PCBM is accelerated by blending it with TQ1. While the NEXAFS spectrum of TQ1 remains unchanged upon illumination in air, its valence band spectrum shows that the occupied molecular orbitals are weakly affected. Yet, UV-Vis absorption spectra demonstrate photo-bleaching of TQ1, which is attenuated in the presence of PCBM in blend films. Illumination of the active layer of TQ1: PCBM solar cells prior to cathode deposition causes severe losses in electrical performance.

Keywords
polymer solar cells, photodegradation, fullerene, near-edge X-ray absorption fine structure
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-37835 (URN)10.1039/c5cp07752d (DOI)000374786300053 ()
Available from: 2015-09-04 Created: 2015-09-03 Last updated: 2018-06-20Bibliographically approved
van Stam, J., Lindqvist, C., Hansson, R., Ericsson, L. & Moons, E. (2015). Fluorescence and UV/VIS absorption spectroscopy studies on polymer blend films for photovoltaics. In: Hayes, SC; Bittner, ER (Ed.), Proceedings of SPIE: Physical Chemistry of Interfaces and Nanomaterials XIV. Paper presented at 2015 Optics + Photonics conference, 9-13 August 2015, San Diego, California, (pp. 95490L1-95490L9). SPIE - International Society for Optical Engineering, 9549
Open this publication in new window or tab >>Fluorescence and UV/VIS absorption spectroscopy studies on polymer blend films for photovoltaics
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2015 (English)In: Proceedings of SPIE: Physical Chemistry of Interfaces and Nanomaterials XIV / [ed] Hayes, SC; Bittner, ER, SPIE - International Society for Optical Engineering, 2015, Vol. 9549, p. 95490L1-95490L9Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2015
National Category
Physical Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-38102 (URN)10.1117/12.2188618 (DOI)000365189200005 ()
Conference
2015 Optics + Photonics conference, 9-13 August 2015, San Diego, California,
Available from: 2015-10-05 Created: 2015-10-05 Last updated: 2018-06-20Bibliographically approved
van Stam, J., Hansson, R., Lindqvist, C., Ericsson, L. & Moons, E. (2015). Fluorescence spectroscopy studies on polymer blend solutions and films for photovoltaics. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 483, 292-296
Open this publication in new window or tab >>Fluorescence spectroscopy studies on polymer blend solutions and films for photovoltaics
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2015 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 483, p. 292-296Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2015
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kau:diva-38100 (URN)10.1016/j.colsurfa.2015.04.003 (DOI)000362146200039 ()
Available from: 2015-10-05 Created: 2015-10-05 Last updated: 2018-06-20Bibliographically approved
Brumboiu, I. E., Ericsson, L. K. .., Hansson, R., Moons, E., Eriksson, O. & Brena, B. (2015). The influence of oxygen adsorption on the NEXAFS and core-level XPS spectra of the C60 derivative PCBM. Journal of Chemical Physics, 142, 054306
Open this publication in new window or tab >>The influence of oxygen adsorption on the NEXAFS and core-level XPS spectra of the C60 derivative PCBM
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2015 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, p. 054306-Article in journal (Refereed) Published
Place, publisher, year, edition, pages
AIP Publishing: , 2015
Keywords
Adsorption, X-ray photoelectron spectroscopy, X-ray absorption near edge structure, Atomic spectra, Fullerenes
National Category
Condensed Matter Physics
Research subject
Physics; Materials Science
Identifiers
urn:nbn:se:kau:diva-35419 (URN)10.1063/1.4907012 (DOI)000349614200019 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationGöran Gustafsson Foundation for Research in Natural Sciences and MedicineSwedish National Infrastructure for Computing (SNIC)
Available from: 2015-03-22 Created: 2015-03-22 Last updated: 2019-10-11Bibliographically approved
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