Improving the performance of organic light-emitting devices by employing oxygen plasma treatment on indium-tin-oxide surfaces

ITO was modified by an oxygen plasma treatment, and its surface characteristics were evaluated by ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and contact angle technologies. The plasma discharge boosted the ITO work function without inducing surface damage, attributed to eliminating carbon contaminants instead of decreasing oxygen vacancy, and improved the surface morphology, confirmed by the smaller root-mean-square. Besides, the plasma treatment increased the surface wettability evaluated by the surface energy, which improved the adhesion between organic molecular and ITO surfaces and was beneficial for realizing high-efficiency devices. The prepared white device based on the oxygen-plasma-treated ITO performed better than the reference white device with a pristine ITO anode, demonstrating higher current efficiencies and power efficiency over a wide range of current densities. The improved efficiency is ascribed to alleviating leakage current density and reducing operating voltages.