Researchers have developed a new method to improve the efficiency and durability of perovskite solar cells by controlling how the materials crystallize. The study shows how a temporary liquid phase can help produce larger, more uniform crystals with fewer defects.

The team, co-led by researchers at the University of California San Diego (UC San Diego), used this approach to improve perovskite-based solar cells and light-emitting diodes. The devices achieved efficiencies of around 24 percent to 26 percent, among the higher values reported for perovskite devices.

Solar cells made using the technique also retained most of their initial efficiency after eight weeks of continuous operation under simulated sunlight.

Perovskites are materials that could help make solar technology more affordable while delivering high efficiency. They can be processed from liquid solutions and deposited as thin films, potentially reducing the energy and complexity required for manufacturing compared with conventional silicon solar cells.

However, producing high-quality perovskite films remains challenging. These films typically contain many small crystals, with boundaries between neighboring crystals known as grain boundaries. Defects in these regions can cause energy losses and reduce device performance.

The problem becomes more significant when manufacturers attempt to produce larger solar panels, where maintaining efficiency across a greater area is difficult.

To address this issue, researchers led by David Fenning, professor of chemical and nano engineering at UC San Diego, worked with colleagues from Princeton University and Sungkyunkwan University in South Korea.

The team added zinc bromide and methylammonium chloride to the solution used to produce a type of material called a halide perovskite.

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