Unveiling the impact of organic cation passivation on structural and optoelectronic properties of two-dimensional perovskites thin films

TL;DR

This study uses density functional theory to analyze how 17 different organic cations influence the structural and optoelectronic properties of two-dimensional perovskite films, identifying three promising passivation agents for practical use.

Contribution

It provides a detailed computational analysis of organic cation effects on 2D perovskite stability and properties, highlighting potential passivation agents for improved material performance.

Findings

Oxygenated groups enhance stability through hydrogen bonding.

Certain cations (FPEA, PEA, BtA) show higher potential for applications.

Interactions affect bond lengths, angles, and electron density distribution.

Abstract

Several organic cations have been used to passivate perovskite films; however, selecting the optimal cation remains challenging. In this work, we carried out density functional theory calculations to understand the effects induced by 17 different organic cations on the passivation (P-cations) of thin two-dimensional P2MAn-1PbnI3n+1 perovskites films, where n = 1 and 2. We found that the interactions between different types of P-cations and the inorganic slab affect the length and angles of the bonds within the inorganic framework (PbI6-octahedra). In general, the binding mechanism includes the interactions of organic cations with the inorganic framework, which leads to the accumulation of electron density within the halides, indicative of Bronsted--Lowry acid-base interactions. Oxygenated groups facilitate additional H-bond formation through -OH and -COOH groups, promoting the localization of the electron density between layers and improving the energetic stability of the system. Based on the results and analysis, we found that three P-cations might have higher potential for real-life applications, namely 4-fluorophenylethylammonium (FPEA), phenylethylammonium (PEA) and butylammonium (BtA).