Improvement of hydrogenated microcrystalline (μc−Si:H) single junction solar cells with upconverter at rear side.

The efficiency of thin film silicon solar cells may be enhanced by a better utilization of the infrared part of the incident light. To this end, a configuration of bifacial cells with an upconverter at the rear side is investigated. A flat thin film silicon solar cell is modeled optically and electronically using numerical semiconductor device simulations with parameters calibrated by experiments. The upconverter itself is described in terms of an effective model of the spectral conversion. The predicted spectral input to the upconverter is shown for a textured cell. Due to optical and electrical losses at the back contact, the geometrical design is optimized with simulations. Finally, the calibrated and optimized device model is used to estimate the potential overall improvement of the cell efficiency.