Electric Field Influences on the Carrier Transport Characteristics of an Individual CsPbBr₃ Microplate

For optoelectronic devices based on lead-halide perovskites and other semiconductors, a comprehensive understanding of the electric field influences on the carrier transport characteristics is critical to the optimization of their practical performances. To fulfill this challenging goal, here we have employed photoluminescence spatial image and transient absorption microscopy measurements on an individual CsPbBr₃ microplate biased at external voltages in an Au/CsPbBr₃/Au device. At the subpicosecond time scale, some photogenerated excitons are dissociated into free electrons and holes that drift toward the electrodes to leave behind unfilled defect sites, which are capable of scattering the residual excitons to yield a reduced diffusion coefficient. While the free electrons drift smoothly across the Au/CsPbBr₃ interface with a p-type Schottky barrier, the free holes are accumulated therein and recombine radiatively with the injected electrons. These electro-optical studies have visualized how the carrier transport characteristics of an individual CsPbBr₃ microplate are connected with the intrinsic defect sites and extrinsic electrode interfaces, which can be naturally extended to other lead-halide perovskites and semiconductors under realistic device operations.