Interface recombination in heterojunction solar cells: Influence of buffer layer thickness

In this article, a theoretical approach for interface recombination in a solar cell with a heterostructure that includes a buffer layer is developed. The focus of the analysis is on the diode quality factor and the activation energy of the saturation current that characterize the diode current. The influence of the buffer layer thickness, recombination velocity, and negative band offsets at two interfaces (absorber/buffer and buffer/window) on these two recombination parameters is studied. The diode quality factor and the activation energy show a dependence on the buffer layer thickness. The activation energy is reduced for negative conduction band offsets on both interfaces.