Ultrafast Photocurrent Microscopy on Methylammonium Lead Iodide Single Crystal Microribbons

Most previous ultrafast pump-probe studies on halide perovskites are primarily based on optical measurements. Here, we performed ultrafast photocurrent microscopic studies on solution-grown single-crystal MAPbI3 microribbons with energetic, temporal, and spatial resolutions, which provide complementary information on charge carrier generation, transport, and collection. The probe pulse induced photocurrent at the metal contacts is suppressed by a pump pulse and its recovery time is shortened by an external electric field. How the time-resolved photocurrent depends on applied bias, temperature, excitation energy, and fluence is systematically investigated. Remarkably, when the photon energy is slightly below the bandgap, we observe a significantly larger photocurrent suppression with an additional sharp peak with a width near ten picoseconds centered at zero-delay that can be attributed to optically modulated Schottky band bending.