Light intensity dependence of the photocurrent in organic photovoltaic devices

Abstract

The competition between recombination and extraction of carriers defines the charge collection efficiency and, therefore, the overall performance of organic photovoltaic devices, including solar cells and photodetectors. In this work, we describe different components of the steady-state light intensity-dependent photocurrent (IPC) and charge collection efficiency under operational conditions. Further, we demonstrate how different loss mechanisms can be identified based on their unique signatures in the IPC. In particular, we show how IPC can be used to distinguish first-order, trap-assisted recombination from other first-order photocurrent loss mechanisms, which dominate at the low-intensity characteristic of indoor light-harvesting applications. The theoretical framework is presented and verified by a one-dimensional drift-diffusion device model. Finally, the extended IPC methodology is validated on organic thin-film photovoltaic devices. We conclude that the relatively straightforward measurement of IPC over a large dynamic range can be a powerful tool for understanding solar and indoor device fundamentals. • IPC is a tool for understanding photovoltaic device fundamentals • Photocurrent loss mechanisms are identified based on their signatures in IPC • The theoretical framework is verified with a drift-diffusion device model • Experimental demonstration of IPC method on state-of-the-art organic solar cells Zeiske et al. present a combined theoretical and experimental study of intensity-dependent photocurrent (IPC), a tool for understanding solar and indoor device fundamentals, to identify different photovoltaic device performance-limiting photocurrent loss mechanisms based on their unique signatures in IPC.