title: Photocurrent generation through electron-exciton interaction at the organic semiconductor donor/acceptor interface.
abstract: In this work, we report our effort to understand the photocurrent generation that is contributed via electron-exciton interaction at the donor/acceptor interface in organic solar cells (OSCs). Donor/acceptor bi-layer heterojunction OSCs, of the indium tin oxide/copper phthalocyanine (CuPc)/fullerene (C60)/molybdenum oxide/Al type, were employed to study the mechanism of photocurrent generation due to the electron-exciton interaction, where CuPc and C60 are the donor and the acceptor, respectively. It is shown that the electron-exciton interaction and the exciton dissociation processes co-exist at the CuPc/C60 interface in OSCs. Compared to conventional donor/acceptor bi-layer OSCs, the cells with the above configuration enable holes to be extracted at the C60 side while electrons can be collected at the CuPc side, resulting in a photocurrent in the reverse direction. The photocurrent thus observed is contributed to primarily by the charge carriers that are generated by the electron-exciton interaction at the CuPc/C60 interface, while charges derived from the exciton dissociation process also exist at the same interface. The mechanism of photocurrent generation due to electron-exciton interaction in the OSCs is further investigated, and it is manifested by the transient photovoltage characteristics and the external quantum efficiency measurements.
authors.affiliation: Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energy, Chongqing 400715, P. R. China. qunliang@gmail.com.
authors.forename: Lijia
authors.initials: L
authors.lastname: Chen
authors.forename: Qiaoming
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yanlian
authors.initials: Y
authors.lastname: Lei
authors.forename: Furong
authors.initials: F
authors.lastname: Zhu
authors.forename: Bo
authors.initials: B
authors.lastname: Wu
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Guoxi
authors.initials: G
authors.lastname: Niu
authors.forename: Zuhong
authors.initials: Z
authors.lastname: Xiong
authors.forename: Qunliang
authors.initials: Q
authors.lastname: Song