Popular Solar Cell Materials Unsuited for Real-World Use

Alexandra Navrotsky
Alexandra Navrotsky

Solar cells made from perovskites have sparked great excitement in recent years because the crystalline compounds boast low production costs and high energy efficiencies. Now UC Davis scientists have found that some promising compounds — the hybrid lead halide perovskites — are chemically unstable and may be unsuited for solar cells.

“We have proven these materials are highly unlikely to function on your rooftop for years,” said Alexandra Navrotsky, interdisciplinary professor of ceramic, earth, and environmental materials chemistry at UC Davis and director of the Nanomaterials in the Environment, Agriculture, and Technology (NEAT) organized research unit.

Perovskites include several types of compounds, all of which share the same crystal structure. They are considered promising solar cell materials for their low cost and ability to efficiently convert sunlight into electricity. But the new UC Davis study suggests hybrid lead halide perovskites will work poorly in solar cells because the materials lack intrinsic thermodynamic stability. This means the hybrid lead halide perovskites will spontaneously decompose to inactive products in a short time (relative to the several years of expected lifespan on a roof). The hybrid perovskites also decompose to inactive products even without exposure to heat, sunlight or humidity (which make such decomposition even faster), the study reports.

The findings were published today (June 27) in the Proceedings of the National Academy of Sciences. Other co-authors include UC Davis postdoctoral scholars G.P. Nagabhushana, the study’s lead author, and Radha Shivaramaiah. The perovskite compounds were analyzed at Peter A. Rock Thermochemistry Laboratory at UC Davis, which has unique experimental capabilities for determining the thermochemical properties of inorganic and hybrid materials. Funding was provided by the U.S. Department of Energy.

 — Becky Oskin, content strategist in the UC Davis College of Letters and Science