Lead-free double perovskites might serve as photocatalysts for solar water splitting. Source: George Volonakis/University of Oxford A new family of water-splitting agents offers scope to improve the efficiency and economy of photocatalytic solar energy storage. Past research has demonstrated that some materials, such as titanium dioxide, can harness sunlight to split water, but its efficiency is limited as it doesn't absorb visible light well.

Four halide double perovskites discovered by researchers from the University of Oxford, UK, and Cornell University are deemed promising photocatalytic materials since they absorb visible light better than titanium dioxide. These compounds also generate electrons and holes that have sufficient energy to split water into hydrogen and oxygen.

Perovskites have attracted interest efficiency boosters for silicon-based solar cells through tandem designs that integrate a perovskite cell directly onto a high-efficiency silicon cell, but they contain a small amount of environmentally hazardous lead.

The researchers used computer simulations to identify a new type of lead-free perovskite with potential for high-efficiency solar cells. These materials may also efficiently split water to facilitate solar energy storage and solar fuel production.

The team cautions that this analysis is theoretical and assumes the compounds form perfect crystals. Evaluations are needed to see if the material works in the real world as well as predicted. Computational analyses will next explore whether these double perovskites have properties useful for other applications such as light detectors.

The research is published in Applied Physics Letters.