Effect of Interface States on the Properties of a-Si:H/c-Si Heterojunction Solar Cells based on Solar materials

The effect of the interface states on the properties of (p(+)) a-Si:H/(n) c-Si heterojunction solar cells is studied by a set of simulations. The results show that there is almost no effect on the short-circuit current. At very low interface states, there is almost no effect on the open-circuit voltage V-OC and the fill factor FF, and then the conversion efficiency. Although, at high interface states, V-OC decreases due to the decrease of the excess minority carrier density at the c-Si neutral region and the increase of the effective interface recombination velocity at the heterojucntion interface, which also results in the decrease of FF. In particular, at very high interface states, the hole transport is limited by the interface potential barrier, which results in S-shaped J-V characteristics and low fill factors. As a result, the conversion efficiency decreases with interface states increasing at high interface states.