Nonlinear Photocurrent Spectroscopy of Layered 2D Perovskite Quantum Wells.

Two-dimensional coherent photocurrent spectroscopies directly probe the electronic states and processes that are relevant to the performance of a photovoltaic device. In this Letter, we apply two-pulse nonlinear photocurrent spectroscopy to a photovoltaic device based on layered perovskite quantum wells. The method effectively decomposes the photovoltaic response into contributions from separate quantum wells and excited-state species (i.e., either single excitons or biexcitons). Our experiments show that the efficiency of photocurrent generation increases with the size of the quantum well. Overall, the results suggest that energy funneling processes in layered perovskites, which are most prominent in transient absorption spectroscopies, are largely irrelevant to the function of a photovoltaic cell.