Tunable work function of a WOx buffer layer for enhanced photocarrier collection of pin-type amorphous silicon solar cells

An in situ postdeposition ultraviolet treatment was proposed to improve the electrical properties of a tungsten oxide (WOx) buffer layer of pin-type amorphous silicon-based solar cell. Based on the x-ray and ultraviolet photoelectron spectroscopy and the activation energy measurements, it was found that the work function of WOx is tunable by ultraviolet light treatment, and the collection performance of solar cells incorporating WOx with the lower work function is further improved. Moreover, the optimal band alignment scheme for a window layer is discussed in terms of obtaining enhanced carrier collection without open circuit voltage degradation.