Nonlocal Screening Dictates the Radiative Lifetimes of Excitations in Lead Halide Perovskites

We use path integral molecular dynamics simulations and theory to elucidate the interactions between charge carriers, as mediated by a lead halide perovskite lattice. We find that the charge-lattice coupling of MAPbI3 results in a repulsive interaction between electrons and holes at intermediate distances. The effective interaction is understood using a Gaussian field theory, whereby the underlying soft, polar lattice contributes a nonlocal screening between quasiparticles. Path integral calculations of this nonlocal screening model are used to rationalize the small exciton binding energy and low radiative recombination rate observed experimentally and are compared to traditional Wannier-Mott and Frohlich models, which fail to do so. These results clarify the origin of the high power conversion efficiencies in lead halide perovskites. Emergent repulsive electron-hole interactions provide a design principle for optimizing soft, polar semiconductors.

Automated summary

In this study, we used path integral molecular dynamics simulations and theory to investigate the interactions between charge carriers in lead halide perovskites mediated by the lattice. The findings reveal a repulsive interaction between electrons and holes at intermediate distances due to the charge-lattice coupling of MAPbI3. A Gaussian field theory is used to explain the effective interaction, taking into account the nonlocal screening between quasiparticles caused by the soft and polar lattice. The results help clarify the origin of the high power conversion efficiencies observed in lead halide perovskites and provide a design principle for optimizing soft, polar semiconductors.