Efficient charge separation at multiple quantum well perovskite/PCBM interface

Low-dimensional organometal halide perovskites have attracted more and more attention because of their good optoelectronic properties and improved stability compared to three-dimensional analogues. In this work, we investigated the charge separation mechanism in multiple quantum well (MQW) perovskite films, which are composed of a mixture of layered perovskites (or quantum wells) with different bandgaps. Despite inefficient dissociation of photo-generated excitons in large-bandgap quantum wells due to the large exciton binding energy, efficient charge separation can occur at the MQW perovskite/electron-extracted-layer interface via energy and/or charge transfer from large-bandgap quantum wells to small-bandgap quantum wells. The MQW perovskite solar cell exhibits a 25-fold improvement in device efficiency, as compared to a pure 2D analogue.