Analysis of Back-Contact Interface Recombination in Thin-Film Solar Cells

The open-circuit voltage (VOC) in a generic TCO/buffer/absorber/back-contact thin-film solar cell device is a key parameter in the recombination analysis. In particular, VOC is sensitively influenced by the interface recombination at the buffer/absorber front interface and at the absorber/back-contact interface. This paper reports the temperature, excitation light intensity, and wavelength-dependent open-circuit voltage analysis to separate and quantify recombination rates in solar cells at the front and back interfaces, in the depletion regions, and in the quasi-neutral region. The wavelength-dependent VOC analysis is exploited to extract the absorber/back-contact recombination coefficient. The experimentally observed results are verified using SCAPS-1D (one dimensional-a solar cell capacitance simulator) simulation.