Photoelectron-Extractive and Ambient-Stable CsPbBr3@SnO2 Nanocrystals for High-Performance Photodetection

The severe recombination of carriers and poor stability against moisture environment have limited the application of CsPbX 3 (X = Cl, Br, I) nanocrystals in photodetection. Herein, a large-scale synthesis of SnO 2 -coated CsPbBr 3 NCs (abbreviated to CsPbBr 3 @SnO 2 NCs) has been reported for the first time by combining the water-triggered transformation of Cs 4 PbBr 6 NCs and the hydrolysis of tin 2-ethylhexanoate. Owing to the construction of the CsPbBr 3 /SnO 2 heterojunction, the recombination rate of carriers in the CsPbBr 3 @SnO 2 NCs is greatly reduced compared to that of the pristine CsPbBr 3 NCs. The stability against water degradation is also improved due to the protection of the SnO 2 coating. Accordingly, a CsPbBr 3 @SnO 2 -graphene hybrid device for high-performance photodetection is demonstrated. Results show that the responsivity of the device reaches 6.2 × $\ \ensuremath{\times{}}$ 10 4 A W −1 at 1 V, which is over 496-fold of the pristine CsPbBr 3 device. This work not only provides a robust approach for the surface modification of CsPbX 3 NCs but also offers useful guidance on the optoelectronic applications with CsPbX 3 NCs.