Ultrafast Charge Separation in Organic Photovoltaics Enhanced by Charge Delocalization and Vibronically Hot Exciton Dissociation

被引:296
作者
Tamura, Hiroyuki [1 ]
Burghardt, Irene [2 ]
机构
[1] Tohoku Univ, WPI Adv Inst Mat Res, Aoba Ku, Sendai, Miyagi 9808577, Japan
[2] Goethe Univ Frankfurt, Inst Phys & Theoret Chem, D-60438 Frankfurt, Germany
关键词
ELECTRON-TRANSFER; TRANSFER STATE; EFFICIENCY; DYNAMICS; POLYTHIOPHENE; INTERFACES; FILMS;
D O I
10.1021/ja4093874
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
In organic photovoltaics, the mechanism by which free electrons and holes are generated, overcoming the Coulomb attraction, is a currently much debated topic. To elucidate this mechanism at a molecular level, we carried out a combined electronic structure and quantum dynamical analysis that captures the elementary events from the exciton dissociation to the free carrier generation at polymer/fullerene donor/acceptor heterojunctions. Our calculations show that experimentally observed efficient charge separations can be explained by a combination of two effects: First, the delocalization of charges which substantially reduces the Coulomb barrier, and second, the vibronically hot nature of the charge-transfer state which promotes charge dissociation beyond the barrier. These effects facilitate an ultrafast charge separation even at low-band-offset heterojunctions.
引用
收藏
页码:16364 / 16367
页数:4
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