10 minute contributed talk for the September 2020 NanoGe online meeting on computational perovskites (ComPer)
Pre-recorded talk: https://youtu.be/TV7dnFbCZ0A
Mobility, Defect Scattering, Vibrational Response of Feynman Polarons in Halide Perovskites
As halide perovskites are soft and polar, they have strong dielectric electron-phonon coupling. This leads to correlated electron and phonon degrees of freedom, the formation of a polaron. In halide perovskites, due to the combination of high electron-phonon coupling and light effective masses, we have the unusual material situation of a strongly-interacting large-polaron.
We implement the Feynman variational approach in a modern code, taking material parameters from density functional and QS-GW electronic structure calculations. From this we have a quantum theory of temperature dependent mobility with no free parameters, and an ansatz for the nature of charge carriers in the material.
We discuss our work in: extending the Feynman theory to explicitly treat the multiple phonon branches; extending our codes to simulate the frequency dependent mobility; predicting the effect of polaron renormalisation on vibrational frequency and spectra; predicting Urbach tails from the instantaneous electric fields in a polar material; and explain slow non-radiative recombination as being due to a reduction in defect scattering cross-section of the Gaussian localised polaron state.