Despite the imperative importance in solar-cell efficiency, the intriguing phenomena at the interface between perovskite solar-cell and adjacent carrier transfer layers are hardly uncovered. Here we show that PbI2/AI-terminated lead-iodide-perovskite (APbI3; A=Cs+/ methylammonium(MA)) interfaced with the charge transport medium of graphene or TiO2 exhibits the sizable/robust Rashba-Dresselhaus (RD) effect using density-functional-theory and ab initio molecular dynamics (AIMD) simulations above cubic-phase temperature. At the PbI2-terminated graphene/CsPbI3(001) interface, ferroelectric distortion towards graphene facilitates an inversion breaking field. At the MAI-terminated TiO2/MAPbI3(001) interface, the enrooted alignment of MA+ towards TiO2 by short-strong hydrogen-bonding and the concomitant PbI3 distortion preserve the RD interactions even above 330 K. The robust RD effect at the interface even at high temperatures, unlike in bulk, changes the direct-type band to the indirect to suppress recombination of electron and hole, thereby letting these accumulated carriers overcome the potential barrier between perovskite and charge transfer materials, which promotes the solar-cell efficiency.
@article{arxiv.1801.05531,
title = {Rashba-Dresselhaus Effect in Inorganic/Organic Lead Iodide Perovskite Interfaces},
author = {Chang Woo Myung and Saqib Javaid and Kwang S. Kim and Geunsik Lee},
journal= {arXiv preprint arXiv:1801.05531},
year = {2018}
}