# Interface Engineering in Hybrid Iodide CH3NH3PbI3 Perovskite Using Lewis Base and Graphene towards High Performance Solar Cells

## TL;DR

This study uses density functional theory to investigate how interface engineering with Lewis bases and graphene improves perovskite solar cell performance by reducing trap states and enhancing stability.

## Contribution

It provides a detailed theoretical analysis of interface interactions, revealing the mechanisms behind performance improvements in hybrid perovskite solar cells.

## Key findings

- Thiocarbamide and thioacetamide form stronger interfaces than DMSO.
- Deep trap states are eliminated at S-donor interfaces.
- Stability is enhanced through increased iodine migration barriers.

## Abstract

Perovskite solar cells have achieved a substantial breakthrough via advanced interface engineerings. Reports have emphasized that combining the hybrid perovskites with Lewis base and graphene improve the performance; the underlying mechanisms are not yet fully understood. Here, using density functional theory, we show that upon the formation of CH3NH3PbI3 interfaces with three different Lewis base molecules and graphene, the binding strength with S-donors thiocarbamide and thioacetamide is higher than with O-donor dimethyl sulfoxide, while the interface dipole and work function reduction tend to increase from S-donors to O-donor. Furthermore, we provide evidences of deep trap states elimination in the S-donor perovskite interfaces through the analysis of defect formation on CH3NH3PbI3(110) surface, and of stability enhancement by estimating activation barriers for iodine atom migrations. These theoretical predictions are in line with the experimental observation of performance enhancement in the perovskites prepared using thiocarbamide.