Measuring Competing Recombination Losses in a Significantly Reduced Langevin System by Steady-State Photoinduced Absorption and Photocurrent Spectroscopy
- Understanding and disentangling photophysical properties of long-lived photoexcitations in bulk heterojunction (BHJ) solar cells, which contribute mostly to photocurrent, provide essential guidelines to their improvement. However, to construct improved physical models, their rational design relies on reliable measurement techniques for charge recombination. Here, we combine photocurrent and photoinduced absorption spectroscopy (PCPIA) to directly probe the free carrier concentration and investigate loss mechanisms of long-lived excitations in nearly 10% efficient PPDT2FBT/PC70BM BHJ solar cells under steady-state operational conditions. From the PCPIA data obtained under open- circuit and short-circuit conditions, the absorption cross section and the concentration of photoexcitations are obtained. This material system exhibits an exceptionally low bimolecular recombination rate, about 300 times smaller than the diffusion-controlled electron and hole encounter rate. Furthermore, we observe that the fill factor is limited by lossesUnderstanding and disentangling photophysical properties of long-lived photoexcitations in bulk heterojunction (BHJ) solar cells, which contribute mostly to photocurrent, provide essential guidelines to their improvement. However, to construct improved physical models, their rational design relies on reliable measurement techniques for charge recombination. Here, we combine photocurrent and photoinduced absorption spectroscopy (PCPIA) to directly probe the free carrier concentration and investigate loss mechanisms of long-lived excitations in nearly 10% efficient PPDT2FBT/PC70BM BHJ solar cells under steady-state operational conditions. From the PCPIA data obtained under open- circuit and short-circuit conditions, the absorption cross section and the concentration of photoexcitations are obtained. This material system exhibits an exceptionally low bimolecular recombination rate, about 300 times smaller than the diffusion-controlled electron and hole encounter rate. Furthermore, we observe that the fill factor is limited by losses originating from long-lived photoexcitations undergoing dispersive bimolecular recombination.…
| Author details: | Le Quang PhuongORCiD, Seyed Mehrdad HosseiniORCiDGND, Chang Woo Koh, Han Young WooORCiD, Safa ShoaeeORCiDGND |
|---|---|
| DOI: | https://doi.org/10.1021/acs.jpcc.9b08901 |
| ISSN: | 1932-7447 |
| ISSN: | 1932-7455 |
| Title of parent work (English): | The journal of physical chemistry : C, Nanomaterials and interfaces |
| Publisher: | American Chemical Society |
| Place of publishing: | Washington |
| Publication type: | Article |
| Language: | English |
| Year of first publication: | 2019 |
| Publication year: | 2019 |
| Release date: | 2020/10/06 |
| Volume: | 123 |
| Issue: | 45 |
| Number of pages: | 6 |
| First page: | 27417 |
| Last Page: | 27422 |
| Funding institution: | Alexander von Humboldt Foundation (Sofia Kovalevskaja award)Alexander von Humboldt Foundation; National Research Foundation of KoreaNational Research Foundation of Korea [2019R1A6A1A11044070] |
| Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
| DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
| Peer review: | Referiert |
