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

All-inorganic perovskite CsPbBr 3 single crystals (SCs) possessing both excellent photoelectric properties and environmental stability have become promising photoelectric materials. However, it remains challenging to prepare high-quality CsPbBr 3 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 CsPbBr 3 SCs. The acquired CsPbBr 3 SCs exhibit a relatively low trap density of 4.02 × 10 9 cm −3 and a relatively high carrier mobility of 89.72 cm 2 V −1 s −1 . Furthermore, the as-grown CsPbBr 3 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 μW cm −2 , the responsivity and external quantum efficiency of the CsPbBr 3 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 μs and a fall time of 6.38 μs 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. High-quality cuboid-shaped CsPbBr 3 single crystals have been grown using a solution refinement modified inverse temperature crystallization method for high-performance photodetectors with a low detection limit of 2.25 nW cm −2 .