Enhancing Intrinsic Stability of Hybrid Perovskite Solar Cell by Strong, yet Balanced, Electronic Coupling

TL;DR

This paper proposes a chemical stabilization mechanism for hybrid perovskite solar cells by replacing methylammonium with alternative cations that enhance electronic coupling, improving stability without compromising efficiency.

Contribution

It introduces a novel approach to stabilize PSCs through balanced electronic coupling by selecting specific alternative cations, addressing a key instability issue.

Findings

Enhanced electronic coupling improves stability of PSCs.

Certain cations like 3
PH3+, 3A0SH2+, and SH3+ are promising stabilizers.

The approach maintains suitable band gap energy for solar applications.

Abstract

In the past few years, the meteoric development of hybrid organic--inorganic perovskite solar cells (PSC) astonished the community. The efficiency has already reached the level needed for commercialization; however, the instability hinders its deployment on the market. Here, we report a mechanism to chemically stabilize PSC absorbers. We propose to replace the widely used methylammonium cation (\ce{CH3NH3+}) by alternative molecular cations allowing an enhanced electronic coupling between the cation and the \ce{PbI6} octahedra while maintaining the band gap energy within the suitable range for solar cells. The mechanism exploits establishing a balance between the electronegativity of the materials' constituents and the resulting ionic electrostatic interactions. The calculations demonstrate the concept of enhancing the electronic coupling, and hence the stability, by exploring the stabilizing features of \ce{CH3PH3+}, \ce{CH3SH2+}, and \ce{SH3+} cations, among several other possible candidates. Chemical stability enhancement hence results from a strong, yet balanced, electronic coupling between the cation and the halides in the octahedron. This shall unlock the hindering instability problem for PSCs and allow them to hit the market as a serious low-cost competitor to silicon based solar cell technologies.