Systems and methods for the design and fabrication of OLEDs, including high-performance large-area OLEDs, are provided. Variously described fabrication processes may be used to deposit and pattern bus lines and/or insulators using vapor deposition such as vacuum thermal evaporation (YTE) through a shadow mask, and may avoid multiple photolithography steps. Bus lines and/or insulators may be formed with a smooth profile and a gradual sidewall transition. Such smooth profiles may, for example, reduce the probability of electrical shorting at the bus lines. Other vapor deposition systems and methods may include, among others, sputter deposition, e-beam evaporation and chemical vapor deposition (CVD). A final profile of the bus line and/or insulator may substantially correspond to the profile as deposited. A single OILED devices may also be formed with relatively large dimension.