Photogeneration and recombination in P3HT/PCBM solar cells probed by time-delayed collection field experiments
- Time-delayed collection field (TDCF) experiments are performed on bulk heterojunction solar cells comprised of a blend of poly(3-hexylthiophene) and [6,6]-phenyl C-71 butyric acid methyl ester. TDCF is analogous to a pump-probe experiment using optical excitation and an electrical probe with a resolution of < 100 ns. The number of free charge carriers extracted after a short delay is found to be independent of the electric field during illumination. Also, experiments performed with a variable delay between the optical excitation and the electrical probe do not reveal any evidence for the generation of charge via field-assisted dissociation of bound long-lived polaron pairs. Photocurrent transients are well fitted by computational drift diffusion simulations with only direct generation of free charge carriers. With increasing delay times between pump and probe, two loss mechanisms are identified; first, charge-carriers are swept out of the device by the internal electric field, and second, bimolecular recombination of the remainingTime-delayed collection field (TDCF) experiments are performed on bulk heterojunction solar cells comprised of a blend of poly(3-hexylthiophene) and [6,6]-phenyl C-71 butyric acid methyl ester. TDCF is analogous to a pump-probe experiment using optical excitation and an electrical probe with a resolution of < 100 ns. The number of free charge carriers extracted after a short delay is found to be independent of the electric field during illumination. Also, experiments performed with a variable delay between the optical excitation and the electrical probe do not reveal any evidence for the generation of charge via field-assisted dissociation of bound long-lived polaron pairs. Photocurrent transients are well fitted by computational drift diffusion simulations with only direct generation of free charge carriers. With increasing delay times between pump and probe, two loss mechanisms are identified; first, charge-carriers are swept out of the device by the internal electric field, and second, bimolecular recombination of the remaining carriers takes place with a reduced recombination coefficient.…
Author details: | Juliane Kniepert, Marcel SchubertORCiD, James C. Blakesley, Dieter NeherORCiDGND |
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DOI: | https://doi.org/10.1021/jz200155b |
ISSN: | 1948-7185 |
Title of parent work (English): | The journal of physical chemistry letters |
Publisher: | American Chemical Society |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Year of first publication: | 2011 |
Publication year: | 2011 |
Release date: | 2017/03/26 |
Volume: | 2 |
Issue: | 7 |
Number of pages: | 6 |
First page: | 700 |
Last Page: | 705 |
Funding institution: | German Federal Ministry of Science and Education (BMBF) within SOHyb [FKZ 03X3525D]; German Research Foundation (DFG) [SPP 1355] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
Peer review: | Referiert |