Perovskite detectors for x-ray imaging and gamma spectroscopy: overview and current state-of-the-art

Perovskites are a family of semiconductor materials with molecular formula ABX3 [where A+ = Cesium (Cs), methylammonium (MA or CH3NH3) or formamidinium (FA or CH(NH2)2), B-site is metal, and X− = chlorine (Cl), bromine (Br) or iodine (I)] that have recently seen a surged interest for X-ray and gamma-ray detection. The all inorganic version, CsPbBr3, grown by high temperature melt method has been demonstrated with an impressive gamma-ray energy resolution of 1.4%@662 keV, while the solution grown CsPbBr3 showed the best achievable resolution of 5.5% at the same energy from a 137Cs source. This paper gives an overview of the development of perovskite in both X-ray detection and gamma spectroscopy, including the most recent advancement with perovskite single crystal grown by low temperature inverse temperature method for solid-state X-ray detector. The crystal shows a decent long carrier diffusion length that is ideal for charge collection, while their mobilities are still not on par with CdZnTe. We also reported our most recent development on clarifying the concepts around X-ray detection limits. The X-ray sensitivity and the lowest detectable dose rate (i.e., X-ray detection limits) of several MAPbI3 detectors made of single crystal were experimentally measured. The best achieved X-ray sensitivity is ~2.5E4 μC/Gyair/cm2 under 15.4 V/mm, which is comparable to the current state-of-the-art MAPbI3 based X-ray detectors (~ 2.3E4 μC/Gyair/cm2 under 4.2 V/mm for GAMAPbI3 (GA=guanidinium) single crystal detector). The best achieved lowest detectable X-ray dose rate for the same MAPbI3 detector is ~61 nGyair/s under 15.4 V/mm, and decreased to ~24 nGyair/s under 3.8 V/mm. The good performance of the MAPbI3 detectors further proves their great potential as the next generation low-cost X-ray detector.