Modeling of photoluminescence of graded band-gap Cu(In, Ga)Se2-Based solar cells

In this work we investigate the voltage dependent luminescence (PLV) of Cu(In, Ga)Se2 cells. The investigated cells apply a graded band gap, which is crucial to attain highly efficient photovoltaic conversion. It will be demonstrated that PLV can serve as a useful tool in investigation of recombination processes in graded absorbers. We preformed PLV measurement for voltages between open circuit and short circuit conditions. The observed evolution of the spectral shape of photoluminescence under external bias can be explained with a shift of position of maximum recombination rate within absorber layer.