Large-Size CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> Single Crystal: Growth and In Situ Characterization of the Photophysics Properties

We reported a facile single-solution fabrication method to grow large-scale CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> hybrid perovskite single crystal at room temperature. The obtained single crystal in this experiment was 14 × 14 mm. The sample’s in situ photophysics properties under dark and illumination, including the surface morphology, work function, surface current distribution, microcosmic <i>I</i>–<i>V</i> curves, as well as the polarization behavior, were in situ characterized by integrated utilization of a scanning probe microscopy, respectively. Piezoresponse force microscopy (PFM) phase angles indicated the existence of “polarization” in CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> lattice. Interestingly, the “polarization effect” was enhanced by the plus light source. Moreover, a surface potential shift as large as 200 mV was observed under the condition of the illumination on and off. This research is proposed to provide an opportunity to take a fresh look at the architectural design and photovoltaic performance origin of the hybrid perovskite solar cells.