Size effects on polaron formation in lead chloride perovskite thin films

AbstractLead halide perovskites (LHP) are of interest for light-emitting applications due to the tunability of their bandgap across the visible and near-infrared spectrum (IR) coupled with efficient photoluminescence quantum yields (PLQY). It is widely speculated that photoexcited electrons and holes spatially separate into large negative (electron) and positive (hole) polarons. Polarons are expected to be optically active. With the observed optoelectronic signatures expecting to show potential excited states within the polaronic potential well. From the polaron excited-state we predict that large polarons should be capable of spontaneous emission, photoluminescence, in the mid-IR to far-IR regime based on the concept of inverse occupations within the polaron potential well. Here we use density functional theory (DFT), including spin–orbit coupling interactions, for calculations on a two-dimensional Dion-Jacobson (DJ) lead chloride perovskite atomistic model of various sizes as a host material for either negative or positive polarons to examine the effects of size on polaron formation. This work provides computational evidence that polaron formation through selective charge injection does not show the same level of localisation for positive and negative polarons.KEYWORDS: Two-dimensional Dion-Jacobson lead halide perovskitepolaron formationpolaron localization AcknowledgementsDRG thanks NSF CHE- 2004197. DSK thanks NSF CHE- 1944921. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231 using allocation award m1251 for 2023, “Computational Modeling of Photo-catalysis and Photo-induced Charge Transfer Dynamics on Surfaces”. We also thank Aaron Forde, Yulun Han, Dinesh Thapa, Landon Johnson, Adam Flesche, Steven Westra, Kamrun Keya, Sarah Ghazanfari, Meade Ericson, Hadassah Griffin, Amara Arshad, Joseph Granlie, William Tupa, and Patricia Adeoye for collective discussion and editing.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by Basic Energy Sciences: [Grant Number DE-AC02-05CH11231]; National Science Foundation: [Grant Number 1944921].