Nucleation-controlled growth of high-quality CsPbBr₃ single crystals for ultrasensitive weak-light photodetectors

All-inorganic perovskite CsPbBr3 single crystals (SCs) possessing both excellent photoelectric properties and environmental stability have become promising photoelectric materials. However, it remains challenging to prepare high-quality CsPbBr3 SCs with regular shape using a solution growth method due to the difference in growth rates along different crystal orientations and the difficulty in controlling the number of nucleation seeds. In this work, a solution refinement strategy has been introduced into the choline bromide assisted inverse temperature crystallization method for achieving high-quality cuboid-shaped CsPbBr3 SCs. The acquired CsPbBr3 SCs exhibit a relatively low trap density of 4.02 x 10(9) cm(-3) and a relatively high carrier mobility of 89.72 cm(2) V-1 s(-1). Furthermore, the as-grown CsPbBr3 SC based photodetector exhibits high photodetection performance, especially ultrasensitive weak light detection performance. Under 530 nm light irradiation with a low light power density of 0.11 mu W cm(-2), the responsivity and external quantum efficiency of the CsPbBr3 SC based photodetector at a bias of 10 V could reach 36.4 A W-1 and 8520%, respectively, and a fast response speed with a rise time of 2.84 mu s and a fall time of 6.38 mu s has been achieved. It is worth noting that the photodetector exhibits an extremely low detection limit of 2.25 nW cm(-2), indicating its great potential for weak light detection.