Bella, FedericoGriffini, GianmarcoCorrea-Baena, Juan-PabloSaracco, GuidoGratzel, MichaelHagfeldt, AndersTurri, StefanoGerbaldi, Claudio2017-01-242017-01-242017-01-24201610.1126/science.aah4046https://infoscience.epfl.ch/handle/20.500.14299/133746WOS:000387816500038Organometal halide perovskite solar cells have demonstrated high conversion efficiency but poor long-term stability against ultraviolet irradiation and water. We show that rapid light-induced free-radical polymerization at ambient temperature produces multifunctional fluorinated photopolymer coatings that confer luminescent and easy-cleaning features on the front side of the devices, while concurrently forming a strongly hydrophobic barrier toward environmental moisture on the back contact side. The luminescent photopolymers re-emit ultraviolet light in the visible range, boosting perovskite solar cells efficiency to nearly 19% under standard illumination. Coated devices reproducibly retain their full functional performance during prolonged operation, even after a series of severe aging tests carried out for more than 6 months.text::journal::journal article::research article