Role of front contact work function on amorphous silicon/crystalline silicon heterojunction solar cell performance

We investigated with numerical simulations the effects that a transparent conductive oxide front contact (TCO) can have on amorphous silicon/crystalline silicon heterojunction solar cells. We found that, due to the extremely thin emitter layer used in this kind of device, the built-in potential available cannot be merely defined by the difference between the work function of the emitter and the base, but it depends on TCO work function as well. As a consequence, because of the correlation between built-in potential and open circuit voltage, the TCO work function strongly affects the solar cell performance. Simulation results show that a higher work function leads to the best device efficiency.