Rashba-Dresselhaus Effect in Inorganic/Organic Lead Iodide Perovskite Interfaces

TL;DR

This study reveals a robust Rashba-Dresselhaus effect at inorganic/organic lead iodide perovskite interfaces, which persists at high temperatures and enhances solar-cell efficiency by modifying electronic band structures.

Contribution

It uncovers the presence and stability of the Rashba-Dresselhaus effect at specific perovskite interfaces using density functional theory and molecular dynamics simulations.

Findings

Rashba-Dresselhaus effect is sizable and robust at interfaces.

Interface distortions facilitate inversion-breaking fields.

The effect suppresses recombination, improving solar-cell efficiency.

Abstract

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 PbI$_2$/AI-terminated lead-iodide-perovskite (APbI$_3$; 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 PbI$_2$-terminated graphene/CsPbI3(001) interface, ferroelectric distortion towards graphene facilitates an inversion breaking field. At the MAI-terminated TiO$_2$/MAPbI$_3$(001) interface, the enrooted alignment of MA$^+$ towards TiO$_2$ by short-strong hydrogen-bonding and the concomitant PbI$_3$ 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.