Researchers at the University of North Carolina at Chapel Hill stabilize solar cells by converting the surfaces of lead halide perovskites to water-insoluble lead oxysalt, as reported in Science. Researchers at Weizmann Institute of Science open a new path to defect management in materials by providing insight into the low defect density of halide perovskites, as reported in Materials Horizon. Researchers at the University of Oxford add ionic liquids to perovskites which markedly improves the devices’ long-term stability, as reported in Nature. Researchers at Kyushu University make exceptionally thick organic light-emitting diodes by combining thin organic light-emitting films with hybrid perovskite charge-transport layers, as reported in Nature.