We report on submicron organosilicate barrier films produced rapidly in ambient by a scalable spray plasma process for improved solar cell stability. The plasma is at a sufficiently low temperature to be compatible with flexible electronic devices. The thickness of the barrier films is tunable and fully transparent over the visible spectrum. The morphology and density of the barrier are shown to improve with the addition of a fluorine-based precursor. Thin-film perovskite solar cells with submicron coatings exhibited significant improvements in stability when exposed to light, heat, and moisture. X-ray diffraction measurements performed while heating showed the barrier film dramatically slows the formation of PbI2. When deposited on a flexible substrate, the barrier films exhibit no signs of cracking or delamination after 10,000 bending cycles on a 127 μm substrate with a bending radius of 1 cm.