Visualization of Carrier Transport in Lateral Metal-Perovskite-Metal Structures and its Influence on Device Operation

The high performance of hybrid perovskite-based devices is attributed to its excellent bulk transport properties. However, carrier dynamics, especially at the metal-perovskite interface, and their influence on device operation are not widely understood. This work presents the dominant transport mechanisms in methylammonium lead iodide (MAPbI3) perovskite-based asymmetric metal electrode lateral devices. The device operation is studied with interelectrode lengths varying from 4 µm to 120 µm. Device characteristics indicate distinct ohmic and space-charge-limited current regimes that are controlled by the interelectrode length and applied bias. The electric-potential mapping using Kelvin-probe microscopy across the device indicates minimal ion-screening effects and the presence of a transport barrier at the metal-MAPbI3 junction. Furthermore, photocurrent imaging of the channel using near-field excitation-scanning microscopy reveals dominant recombination and charge-separation zones. These lateral devices exhibit photodetector characteristics with a responsivity of about 51 mA/W in self-powered mode and 5.2 A/W at 5 V bias in short-channel devices (4 µm). The low device capacitance enables a fast light-switching response of approximately 12 ns.