Design of Si/Ge Dual Junction Solar Cell Devices

Dual junction tandem solar cells can harvest a broader range of incident photons from the solar spectrum compared to single junction solar cells. In this paper dual junction three terminal Si/Ge solar cell devices were designed and optimized in terms of thicknesses and doping concentrations of their active layers. They were then simulated for different operating temperatures, spectra and light concentrations. Four devices with total thicknesses of 10, 20, 50 and 100 μm were considered, and these devices had predicted efficiencies ranging between 14.5% and 17.9% under AM1.5G, 25 °C and 1 sun. Our devices also achieved higher conversion efficiencies under increased light concentration, where the highest predicted efficiency was about 29% under 1000 suns. The tandem devices show promising performance for applications in PV, thermal PV and concentrated PV.