Similar to molybdenum oxide films apply to tungsten and tantalum oxides. However, unlike molybdenum oxides, these oxides facilitate the passage of electrons and prevent the transport of holes (electron transport layers, ETL). Of particular interest are tantalum oxides which, when doped with fluorine and carbon, show high electron mobility.

Details about solar cells and LEDs based on organic semiconductors and perovskites are given by the team of Dr. Vasilopoulou and Dr. Argitis.