Atmospheric pressure or open-air plasmas can be directly integrated with in-line production. We use a blown arc discharge system that ionizes gas as it passes through the high-voltage region—which generates an arc with the grounded wall of the plasma system—and the resulting discharge is blown out of a nozzle and directed onto the substrate. The uniqueness of the plasma system is the combination of energy sources which are generated: reactive species (ions, radicals, metastables, and photons) are produced in combination with convective heat to rapidly transfer energy to enable ultrafast precursor conversion. Furthermore, the precursor (either in liquid or vapor form) can be directly injected into the afterglow of the plasma to provide additional energy for precursor dissociation or fragmentation. We have focused on using spray coating as a technique for liquid precursor delivery of numerous types of materials. We have shown that stoichiometry, composition, growth rate, density, and defectivity can be controlled through this process for chemistries such as silica, titania, tin oxide, and perovskites without additional annealing to form high-quality, scalable device layers. There is also a clear path for transparent conducting oxides, semiconducting charge transport layers, battery electrode materials, and even tandem module fabrication.