Photocurrent Mapping in Single-Crystal Methylammonium Lead Iodide Perovskite Nanostructures

We investigate solution-grown single-crystal methylammonium lead iodide (MAPbI₃) nanowires and nanoplates with spatially resolved photocurrent mapping. Sensitive perovskite photodetectors with Schottky contacts are fabricated by directly transferring the nanostructures on top of pre-patterned gold electrodes. Scanning photocurrent microscopy (SPCM) measurements on these single-crystal nanostructures reveal a minority charge carrier diffusion length up to 21 µm, which is significantly longer than the values observed in polycrystalline MAPbI₃ thin films. When the excitation energy is close to the bandgap, the photocurrent becomes substantially stronger at the edges of nanostructures, which can be understood by the enhancement of light coupling to the nanostructures. Temperature and gate dependent SPCM results will also be shown and discussed to illustrate the charge transport mechanisms. These perovskite nanostructures with long carrier diffusion lengths and strong photonic enhancement not only provide an excellent platform for studying their intrinsic properties but may also boost the performance of perovskite-based optoelectronic devices.