ABSTRACT
The thin films of transparent conducting oxides (TCOs) have widespread applications owing to their unique properties of good electric conductivity and high optical transparency in the visible spectrum range. Indium–tin oxide (ITO) is one of the most frequently used TCO materials in practical applications. ITO film has attracted much attention because of its unique characteristics, such as good electric conductivity, high optical transparency over the visible wavelength region, excellent adhesion to substrates, stable chemical property, and easy patterning ability. One of the most common uses of ITO coatings has been as transparent electrodes in photovoltaic cells and flat-panel displays, including plasma televisions, liquid crystal displays, and OLEDs. In OLEDs, ITO acts as hole-injection electrode that requires a large work function to match the highest occupied molecular orbital of the adjacent organic material for efficient carrier injection. However, in solar cells, ITO serves as an electron collector being more efficient with a low work function.
