title: Ultrafast charge transfer in operating bulk heterojunction solar cells.
abstract: The ultrafast charge generation process in organic solar cell devices is investigated by transient reflection spectroscopy on five state-of-the-art bulk heterojunction systems. The charge generation process in operating devices is found to be a combination of an ultrafast generation mechanism over several hundred femto-seconds and a slow process from pico-seconds to nanoseconds, limited by exciton diffusion dynamics. In addition, the lack of electric field dependence in the charge dynamics rules out geminate recombination as an important loss mechanism.
authors: Center for Polymers and Organic Solids, University of California, Santa Barbara, CA, 93106-5090, USA; State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou, 510640, PR China.
authors: Chengmei
authors: C
authors: Zhong
authors: Hyosung
authors: H
authors: Choi
authors: Jin Young
authors: JY
authors: Kim
authors: Han Young
authors: HY
authors: Woo
authors: Thanh Luan
authors: TL
authors: Nguyen
authors: Fei
authors: F
authors: Huang
authors: Yong
authors: Y
authors: Cao
authors: Alan J
authors: AJ
authors: Heeger
keywords: bulk heterojunctions; organic solar cells; transient reflection spectroscopy; ultrafast charge transfer