Tao’s group harvested MAPbI3 single crystal with the large size by using the BSSG method. They put a seed into growth chamber and the growth process is initiated by lowering the temperature. Slowly reducing the temperature from 65 to 40 °C to induce saturation of the solute, the MAPbI3 single crystal with the largest dimensions of 10 mm × 10 mm × 8 mm was successfully attained in the bottom of the flask, taking about one month. It is worth noting that the temperature of the precursor solution is uniform during crystal growth, and the temperature of the solution is lowered at a preprogrammed rate by programmable temperature controller