While investigating perovskite crystals, University of Groningen scientists made an observation that could make perovskite solar cells more efficient. It could also lead to sensors for oxygen and water vapor. The results were published online by the journal Science Advances. Photovoltaic cells based on hybrid perovskites were first introduced in 2009, and they rapidly became as efficient as standard silicon solar cells. They now convert light into electricity at about 22% efficiency.