talk-icon
Description
Dayton Vogel1 Talgat Inerbaev3 Dmitri Kilin1 2

1, University of South Dakota, Vermillion, South Dakota, United States
3, L.N. Gumilyov Eurasian National University, Astana, , Kazakhstan
2, North Dakota State University, Fargo, North Dakota, United States

Methylammonium lead iodide perovskite materials have been shown to be efficient in photovoltaic devices. The current fabrication process has not been perfected, leaving defects such as site vacancies, which can trap charge and have a detrimental effect on photogenerated charge carriers. Here, focus is placed on the effect a Pb site vacancy has on the morphology and charge carrier dynamics following photoexcitation. Excited state electronic structures are often found in open shell configurations with a single unpaired electron in the conduction band. To accurately describe unpaired electrons, spin-polarized calculations are performed on both neutral and charged vacancy systems. This work presents spin-polarized ground state electronic structures, non-radiative rates of charge carrier relaxation, and introduces an extension to a novel procedure to compute photoluminescence spectra for open shell models. Electronic structure calculations are done in VASP with the PBE functional and plane wave basis set and the charge carrier dynamics are computed using Redfield theory within the reduced density matrix formalism. Early results show the vacancy of the Pb ion introducing a new energy state within the unblemished material band gap region. This additional unoccupied state is expected to increase the non-radiative relaxation lifetime of the excited electron, allowing for a longer lifetime of the charge carrier and increased opportunity for secondary relaxation mechanisms or collection to take place.

Tags