Co₃O₄ based all-oxide PV: A numerical simulation analyzed combinatorial material science study

Here we investigate the impact of four different metal back contacts on the photovoltaic (PV) performance of Co₃O₄ thin film all-oxide photovoltaic cells. A combinatorial TiO₂|Co₃O₄ heterojunction thin film device library was made with thickness gradients for both metal oxide layers. Grids of four different metal back contacts were then deposited on top of these layers. A significant effect of the metal back contacts on the final photoconversion performance has been observed by combinatorial PV measurements. We analyze these results via advanced numerical simulations and different scenarios in order to explain the recombination mechanisms at the different back contacts. We conclude that the nature of the back contact material controls the density of surface states and, therefore, the undesirable surface recombination at the absorber-back contact interface.