Efficient subphthalocyanine/C60 planar heterojunction photovoltaic device with buffer layer of molybdenum oxide

In this report, we have studied the performance of a subphthalocyanine (SubPc)/C₆₀ heterojunction photovoltaic device as a function of various anode conditions: pristine indium-tin-oxide (ITO), oxygen plasma treated ITO, and insertion of molybdenum oxide (MoO₃) as a buffer layer at the anode interface. The insertion of MoO₃ increases considerably the open-circuit voltage by more than two times. Although, a similar effect is also observed for the ITO treated by oxygen plasma, the MoO₃ thin film allows the device to operate at an optimum optical condition, as predicted by using a simulation model with a theory of transfer matrix. A slight increase in fill factor is attributed to the efficient hole extraction owing to a matched energy level alignment after the insertion of MoO₃.