Perovskite flaws can improve solar device efficiency

“Perovskites are the fastest-growing class of photovoltaic material over the past four years,” said Dane deQuilettes, a UW doctoral student working with David Ginger, professor of chemistry and associate director of the UW’s Clean Energy Institute.

“In that short amount of time, the ability of these materials to convert sunlight directly into electricity is approaching that of today’s silicon-based solar cells, rivalling technology that took 50 years to develop,” deQuilettes said in a statement. “But we also suspect there is room for improvement.”

The research team, whose work is published in Science, is said to have used high-powered imaging techniques to find defects in the perovskite films that limit the movement of charges and limit the efficiency of the devices. Perovskite solar cells have so far have achieved efficiencies of roughly 20 per cent, compared to about 25 per cent for silicon-based solar cells.

In a collaboration made possible by the Clean Energy Institute, the team used confocal optical microscopy, which is more often used in biology, and applied it to semiconductor technology. They used fluorescent images and correlated them with electron microscopy images to find “dark” or poorly performing regions of the perovskite material at intersections of the crystals. In addition, they reportedly discovered that they could “turn on” some of the dark areas by using a chemical treatment.