Ultrafast Carrier Dynamics Study on Graphene Oxide-CsPbBr₃ Nanocomposites

The combination of inorganic perovskite and grapheneoxide hasbeen demonstrated to be an efficient strategy for obtaining excellentoptical and electrical properties. In this work, high-quality CsPbBr3 nanocrystals are loaded on graphene oxide (GO) to form GO-CsPbBr3 nanocomposites by post-mixing of the two materials. The photoluminescencespectra indicated that GO could dramatically quench the luminescenceof the pristine-CsPbBr3 nanocrystals in the GO-CsPbBr3 nanocomposites, which is probably induced by the fast separationand transfer of the photogenerated hole-electron pair. Thefast separation and transfer of the photogenerated hole-electronpair between GO and CsPbBr3 nanocrystals have been confirmedby an ultrafast transient absorption study, and a lifetime tau= 18.6 +/- 4.1 ps of electron transfer from CsPbBr3 nanocrystalsto GO could be obtained. In addition, the GO could significantly boostthe photocurrent intensity; the photocurrent of GO-CsPbBr3 nanocomposites is about 2.5 times that of the pristine-CsPbBr3 nanocrystals. Photoelectrochemical switching on and off canbe achieved by using intermittent visible light exposure. These resultsreveal that GO may act as an electron collector to extract electronsfrom CsPbBr3 nanocrystals, suggesting a new potential applicationof GO-CsPbBr3 nanocomposites for photocatalysis.