Uncovering the Electron-Phonon Interplay and Dynamical Energy-Dissipation Mechanisms of Hot Carriers in Hybrid Lead Halide Perovskites

摘要

The discovery of slow hot carrier cooling in hybrid organic-inorganic lead halide perovskites (HOIPs) has provided exciting prospects for efficient solar cells that can overcome the Shockley-Queisser limit. Questions still loom over how electron-phonon interactions differ from traditional polar semiconductors. Herein, the electron-phonon coupling (EPC) strength of common perovskite films (MAPbBr(3), MAPbI(3), CsPbI3, and FAPbBr(3)) is obtained using transient absorption spectroscopy by analyzing the hot carrier cooling thermodynamics via a simplified two-temperature model. Density function theory calculations are numerically performed at relevant electron-temperatures to confirm experiments. Further, the variation of carrier-temperature over a large range of carrier-densities in HOIPs is analyzed, and an "S-shaped" dependence of the initial carrier-temperature to carrier-density is reported. The phenomenon is attributed to the dominance of the large polaron screening and the destabilization effect which causes an increasing-decreasing fluctuation in temperature at low excitation powers; and a hot-phonon bottleneck which effectively increases the carrier temperature at higher carrier-densities. The turning point in the relationship is indicative of the critical Mott density related to the nonmetal-metal transition. The EPC analysis provides a novel perspective to quantify the energy transfer in HOIPs, electron-lattice subsystem, and the complicated screening-bottleneck interplay is comprehensively described, resolving the existing experimental contradictions.