Simulation study on lead-free double Cs2AgBiBr6/GaAs tandem solar cells

Cs2AgBiBr6, a double perovskite devoid of lead, is a remarkable alternative to traditional perovskite solar cells. This research utilised Silvaco TCAD simulation software to construct and examine lead-free double Cs2AgBiBr6/gallium arsenide tandem devices. By optimising the perovskite layer thickness, the thickness and doping concentration of the gallium arsenide base layer, selecting an appropriate carrier transport layer thickness, and integrating an anti-reflective layer, the conversion efficiencies of the four-terminal lead-free double Cs2AgBiBr6/gallium arsenide tandem solar cell is achieved up to 31.71%. Based on the study of 4-T tandem devices, current matching of 2-T tandem devices was performed. The 2-T tandem device achieved an energy conversion efficiency of 26.35% by optimising the doping concentration of the GaAs substrate layer. Furthermore, the 2-T tandem device energy conversion efficiency remains at 23.40% following the current matching under spectral AM0, which has the potential application in space.