Asymmetric charge carrier transfer and transport in planar lead halide perovskite solar cells

Abstract

Understanding charge carrier extraction from the perovskite photoactive layer is critical to optimizing the design of perovskite solar cells. Herein, we demonstrate a simple time-resolved photoluminescence method to characterize the kinetics of charge transport across the bulk perovskite and charge transfer from the perovskite layer to the interlayers, elucidating the dependence of these dynamics on film thickness, grain boundaries (GBs), and interlayers. Using asymmetric laser excitation, we selectively probe charge transport by generating charges both close to and far from the heterojunction interface and correlate these results with device performance. We observe that both film thickness and GBs affect the asymmetry between electron and hole charge transport across the bulk perovskite and charge transfer from the bulk perovskite to the respective interlayers. • Time-resolved photoluminescence with spatially localized excitation • Asymmetries of charge carrier transfer and transport are quantified • Lateral grain boundaries result in unbalanced charge transport • Aerosol-assisted solvent treatment removes lateral grain boundaries effectively Xu et al. demonstrate a simple time-resolved photoluminescence method to selectively probe charge transfer and charge transport in perovskite films with interlayers. The results show both film thickness and grain boundaries affect the asymmetry between electron and hole charge transfer and charge transport.