Fig. 2: Carrier transport probed by scanning photocurrent microscope (SPCM).

a Schematic illustration of the SPCM setup. b Polarized optical image of the MAPbI₃ single crystal lateral device (upper panel) and the photocurrent line scan profile across the conductive channel (lower panel) with increased electric field from 1 V mm⁻¹ to 10 V mm⁻¹ after crystal surface passivation. The horizontal black solid line indicates the photocurrent line-scan trace, the pink solid line is a guide to eye. c Proposed electric field distribution across the conductive channel. d The corresponding simulation results of the photocurrent profile without and with the electric field discontinuity.