Organic light-emitting diodes with a nanostructured TiO2 layer at the interface between ITO and NPB layers

Organic light-emitting diodes (OLEDs) with a nanostructured TiO₂ layer at the interface between indium tin oxide and a-naphtylphenyliphenyl diamine layers were fabricated using a vacuum evaporation method. The nanostructured TiO₂ layer was achieved by the Sol–Gel method. Compared to the different thickness of the buffer layer, the OLEDs with the 6 nm buffer layer showed the highest efficiency. The enhancements in efficiency result from an improved balance of hole and electron injections and a more homogeneous adhesion of the buffer layer inserted.