High‐Quality Cuboid CH3NH3PbI3 Single Crystals for High Performance X‐Ray and Photon Detectors

Abstract Organic–inorganic halide hybrid perovskite materials are promising materials for X‐ray and photon detection due to their superior optoelectronic properties. Single‐crystal (SGC) perovskites have increasingly attracted attention due to their substantially low crystal defects, which contribute to improving the figures of merit of the devices. Cuboid CH 3 NH 3 PbI 3 SGC with the naturally favorable geometry for device fabrication is rarely reported in X‐ray and photon detection application. The concept of seed dissolution‐regrowth to improve crystal quality of cuboid CH 3 NH 3 PbI 3 SGC is proposed and a fundamental understanding of the nucleation and growth is provided thermodynamically. The X‐ray detector fabricated from cuboid CH 3 NH 3 PbI 3 SGC demonstrates the firstly reported high sensitivity of 968.9 µC −1 Gy −1 cm −2 under −1 V bias. The results also show that the favorable crystal orientation and high quality of cuboid CH 3 NH 3 PbI 3 leads to better responsivity and faster response speed than the more common dodecahedral CH 3 NH 3 PbI 3 in photodetection. Consequently, the work paves a way to synthesize high‐quality perovskite SGCs and benefits the application of MAPbI 3 SGCs with preferred crystal orientation and favorable crystal geometry for emerging device applications.