First-Principles Study Lead-Free Halide Double Perovskite Cs2RhAgX6 and Cs2IrAgX6 (X = Cl, Br and I)

TL;DR

This study uses first-principles calculations to explore lead-free double perovskites Cs2RhAgX6 and Cs2IrAgX6, revealing their stability, tunable band gaps, and strong light absorption, indicating potential for optoelectronic applications.

Contribution

It provides the first detailed theoretical analysis of Cs2RhAgX6 and Cs2IrAgX6 double perovskites, highlighting their stability and optoelectronic properties.

Findings

Higher thermodynamic stability compared to lead-based perovskites

Band gaps decrease from 0.55 to 2.2 eV with halogen substitution

Strong light absorption across the visible spectrum

Abstract

In contrast to lead-based perovskites, double perovskites have attracted considerable interest due to their ability to modulate photovoltaic properties and high stability through elemental control. However, most double perovskites are mainly faced with large band gap ranges and indirect band gaps. Here, we report the structural, electronic, and optical properties of the double perovskites Cs2RhAgX6 and Cs2IrAgX6 (X = Cl, Br and I) by first-principles calculations. The results of the thermodynamic stability and electronic properties show that the double perovskites have a higher stability and exhibit a suitable band gap range in the field of optoelectronics, their band gap decrease with the substitution of halogen elements from Cl to I (0.55-2.2 eV). In addition, the double perovskite exhibits strong light absorption. These results suggest a great potential for Cs2RhAgX6 and Cs2IrAgX6 (X = Cl, Br and I) perovskites in optoelectronic applications.