Evidence of Hot Charge Carrier Transfer in Hybrid CsPbBr3/Functionalized Graphene

Abstract

AbstractLead halide perovskite nanocrystals (NCs) are extremely important as an absorber material for hot carrier (HC) solar cells. The extraction of the above‐bandgap excess energy of HC is essential to improve the device‘s performance. The fundamental understanding of the HC transfer process at the perovskite interface remains challenging. We have investigated the hot‐electron transfer dynamics at hybrid CsPbBr3/ thiol functionalized reduced graphene oxide (rGo−Ph−SH) using ultrafast transient absorption spectroscopy. Analysis reveals the significant drop in HC carrier temperature (from 1040 to 700 K) and HC cooling time (from 530 to 250 fs) in hybrid CsPbBr3/rGO−Ph−SH, suggesting the efficient hot electron transfer from CsPbBr3 NCs to surface anchored rGo−Ph−SH. We examine the HC relaxation mechanism using the electron‐longitudinal optical (LO) phonon coupling model and confirm the hot electron transfer. Here, we found that the hot‐electron transfer is three times faster than band‐edge electron transfer, with a maximum transfer efficiency of 43%. These findings shed new light on the study of the HC dynamics that could be beneficial for optoelectronic devices.