Zwitterion Assisted Growth and Strain Optimisation of Perovskite Single Crystals for High Performance Photon Counting Radiation Detection

Abstract

Solution-grown perovskite single crystals (SCs) have shown great interest in the radiation detection community due to the easier growth process and the cost effectiveness compared to conventional semiconductor materials such as cadmium telluride (CdTe), cadmium zinc telluride (CdZnTe), as well as melt-grown perovskite materials such as CsPbBr3 (CPB). However, their performance as photon-counting radiation detectors is lacking compared to melt-grown semiconductor materials. This is due to the potential for the solution-growth method to cause unregulated crystal growth and poor scalability of high-quality SCs due to spontaneous nucleation. In this work, with the utilisation of the sulfonic zwitterionic ligand 3-(Decyldimethylammonio)­propane­sulfonate inner salt (DPSI), we have grown high-quality FAPbBr3 (FPB) SCs with low defect densities. By also optimising the crystal growth temperature ramp, we have achieved ‘low-strained’ FPB SCs with reduced internal strain. These SC devices show excellent charge transport properties, showing a high hole mobility of 190 cm2 V-1 s-1 and a high hole mobility-lifetime (µτ) product of 2.7 x 10-3 cm2 V-1, with a low dark current of 2.9 nA cm-2 operating at a field strength of 1000 V cm-1. These devices have achieved an energy resolution of 10.5% FWHM for 241Am 5.49 MeV α-particles, and 25.6% FWHM for 241Am 59.5 keV γ-rays, and a high X-ray photocurrent sensitivity of 5111 µC Gyair⁻¹ cm⁻2 for 50 kV X-rays, showing great promise as a room temperature radiation detector capable of operating efficiently in both photon-counting and current modes.