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 attracted great interest in the radiation detection community due to their easier growth process and cost-effectiveness compared to conventional semiconductor materials such as cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe), as well as melt-grown perovskite materials such as CsPbBr₃ (CPB). However, their performance as photon-counting radiation detectors is inferior to that of melt-grown semiconductor materials. This is due to the potential of the solution-growth method to cause unregulated crystal growth and poor scalability of high-quality SCs due to spontaneous nucleation. In this work, using the sulfonic zwitterionic ligand 3-(decyldimethylammonio)propanesulfonate inner salt (DPSI), we have grown high-quality FAPbBr₃ (FPB) SCs with low defect densities. Also, by optimising the crystal growth temperature ramp, we have obtained ‘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 × 10⁻³ cm² V⁻¹, with a low dark current of 2.9 nA cm⁻² 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 Gy_air⁻¹ cm⁻² for 50 kV X-rays, showing great promise as room-temperature radiation detectors capable of operating efficiently in both photon-counting and current modes.