Hedley, Gordon J. and Steiner, Florian and Vogelsang, Jan and Lupton, John M. (2017) Determining the True Optical Gap in a High-Performance Organic Photovoltaic Polymer Using Single-Molecule Spectroscopy. JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 8 (15). pp. 3494-3499. ISSN 1948-7185,
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Low-gap conjugated polymers have enabled an impressive increase in the efficiencies of organic solar cells, primarily due to their red absorption that allows harvesting of that part of the solar spectrum. Here we report that the true optical gap of one prototypical material, PTB7, is in fact at significantly higher energy than has previously been reported, indicating that the red absorption utilized in these materials in solar cells is entirely due to chain aggregation. Using single-molecule spectroscopy we find that PL from isolated nanoscale aggregates consists of multiple independently emitting chromophores. At the single-molecule level, however, straight single chains with a high degree of emission polarization are observed. The PL is found to be similar to 0.4 eV higher in energy, with a longer lifetime than the red aggregates, and is attributed to single chromophores. Our findings indicate that the impressive light-harvesting abilities of PTB7 in the red spectral region arise solely from chain aggregation.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | POWER-CONVERSION EFFICIENCY; SOLAR-CELLS; INTENSITY FLUCTUATIONS; FLUORESCENCE; LIGHT; INTERFEROMETRY; RADIATION; PHOTONS; DESIGN; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group John Lupton |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Dec 2018 13:16 |
| Last Modified: | 20 Feb 2019 07:47 |
| URI: | https://pred.uni-regensburg.de/id/eprint/1396 |
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