Interface energetics at WOX/organic interfaces: The role of oxygen vacancies.

Oxygen vacancy in tungsten oxide (WOX) is critical to the interface energetics for charge injection and transport in organic electronic devices. Here, we systematically studied the impact of oxygen vacancy on electronic structures of the WOX/organic hole-transport layer interface via photoemission spectroscopy. The partial reduction of W cations and a decrease in its work function were observed by controlling the degree of oxygen vacancies in WOX with thermal annealing, which are due to the partial filling of the unoccupied 5d orbitals. The increase in oxygen deficiency caused the increase of hole-injection barrier at WOX/organic interfaces. [ABSTRACT FROM AUTHOR]