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Efficient Exciton Harvesting through Long‐Range Energy Transfer
Author(s) -
Wang Yanbin,
Ohkita Hideo,
Benten Hiroaki,
Ito Shinzaburo
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201402740
Subject(s) - exciton , energy transfer , range (aeronautics) , energy harvesting , chemical physics , chemistry , nanotechnology , energy (signal processing) , materials science , photochemistry , physics , condensed matter physics , quantum mechanics , composite material
Efficient exciton collection at charge‐generation sites is one of the key requirements for the improvement in power conversion efficiency (PCE) of organic solar cells, because only excitons arriving at a donor/acceptor interface can be dissociated into free charge carriers. We evaluated the effective diffusion length in poly(3‐hexylthiophene) (P3HT) by using donor/acceptor bilayers with two different exciton‐quenching acceptors. One is an insoluble fullerene polymer (p‐PCBVB), which is an efficient electron‐accepting material with negligible absorption in the visible region. The other is a low‐bandgap polymer, poly[(4,4‐bis(2‐ethylhexyl)‐dithieno[3,2‐b:2′,3′‐d]silole)‐2,6‐diyl‐ alt ‐(2,1,3‐benzothiadiazole)‐4,7‐diyl], (PSBTBT). This polymer has a large absorption band in the near‐IR region, which overlaps well with the emission band of P3HT. The effective diffusion length of P3HT excitons is evaluated to be 15 nm for P3HT/p‐PCBVB bilayers and improved to 30 nm for P3HT/PSBTBT bilayers. This improvement is ascribed to long‐range energy transfer from P3HT to PSBTBT. This finding suggests that the effective diffusion length of P3HT excitons can be increased through long‐range energy transfer by incorporating PSBTBT into P3HT/PCBM blends.