Hot Hole Cooling and Transfer Dynamics from Lead Halide Perovskite Nanocrystals Using Porphyrin Molecules

Abstract

A deep understanding of hot carrier (HC) dynamics is important to improve the performance of optoelectronic devices by reducing the thermalization losses. Here, we investigate the hot hole cooling and transfer dynamics of CsPbBr3 nanocrystals (NCs) using 5,10,15,20-tetra(4pyridyl) porphyrin (TpyP) molecules. Density functional theory (DFT) is used to elucidate the mechanism underlying charge extraction as well as the HC transfer process in the CsPbBr3–TpyP system. It is noted that the hot hole states are localized around the top surface of CsPbBr3, while the hot electron states are delocalized away from its top surface, indicating easy extraction of hot holes from the CsPbBr3 by TpyP molecules, as compared to the hot electrons. The significant drop of initial hot carrier temperature from 1140 to 638 K at 400 nm excitation confirms the hot hole transfer from CsPbBr3 NCs to TpyP molecules, which is dependent on the excitation energy, and the maximum transfer efficiency is found to be 42% (for 0.85 eV above band edge photoexcitation). In addition, the hot hole transfer rate is almost 11 times faster than the band edge hole transfer rate. Our findings are relevant for the development of next-generation perovskite-based optoelectronic devices.