A team of scientists from the Energy Department’s National Renewable Energy Laboratory (NREL) determined that surface recombination limits the performance of polycrystalline perovskite solar cells.   Research into perovskites at NREL and elsewhere has proved the material’s effectiveness at converting sunlight into electricity, routinely topping 20% efficiency. The sunlight creates mobile electrons whose movement generates the power but upon encountering defects can slip into a non-productive p...