Ultrafast Carrier Dynamics Study on Graphene Oxide-CsPbBr₃ Nanocomposites

The combination of inorganic perovskite and graphene oxide has been demonstrated to be an efficient strategy for obtaining excellent optical and electrical properties. In this work, high-quality CsPbBr 3 nanocrystals are loaded on graphene oxide (GO) to form GO-CsPbBr 3 nanocomposites by post-mixing of the two materials. The photoluminescence spectra indicated that GO could dramatically quench the luminescence of the pristine-CsPbBr 3 nanocrystals in the GO-CsPbBr 3 nanocomposites, which is probably induced by the fast separation and transfer of the photogenerated hole–electron pair. The fast separation and transfer of the photogenerated hole–electron pair between GO and CsPbBr 3 nanocrystals have been confirmed by an ultrafast transient absorption study, and a lifetime τ = 18.6 ± 4.1 ps of electron transfer from CsPbBr 3 nanocrystals to GO could be obtained. In addition, the GO could significantly boost the photocurrent intensity; the photocurrent of GO-CsPbBr 3 nanocomposites is about 2.5 times that of the pristine-CsPbBr 3 nanocrystals. Photoelectrochemical switching on and off can be achieved by using intermittent visible light exposure. These results reveal that GO may act as an electron collector to extract electrons from CsPbBr 3 nanocrystals, suggesting a new potential application of GO-CsPbBr 3 nanocomposites for photocatalysis.