Investigation of carrier transport through perovskite crystal junctions with in-situ replaceable electrodes

Metal electrode materials play a crucial role in determining the performance of microscale perovskite-based devices. However, it is a great challenge to in situ investigate the influence of different metal electrode materials on the performance of the same piece of a microscale perovskite due to the strong bonding between the perovskite and the electrode. To this end, a strategy to fabricate soft-sandwiched perovskite junctions by employing a liquid metal as top electrode was put forward. By taking full use of the adhesion of the top liquid metal electrode, the bottom electrode can be freely replaced by different metal materials without mechanical damage and chemical contamination. It is demonstrated that the shape of the instantaneous photocurrent upon light illumination and the rectification behavior of perovskite junctions can be controlled by the electrode materials and the light intensity. The shape of instantaneous photocurrent is mainly controlled by the light intensity rather than electrode materials. In contrast, the rectification ratio is mainly determined by the electrode materials instead of the light intensity. The underlying mechanism for these observations is elucidated based on the energy-level alignment in the junctions. The detachable soft junctions are expected to be widely applied to study the influence of external electrodes on the carrier transport of various microscale/nanoscale objects.