Design and simulation analysis of narrow bandgap single-junction GaAs-GaAsSb nanowire solar cell

Solar cell efficiency improvement is a significant research focus. To enhance the separation and reduce the recombination of photogenerated carriers in narrow bandgap GaAs nanowire solar cells (NWSCs), we propose a GaAs-GaAs_1-xSb_x-GaAs heterostructure NWSCs model. Adjusting the Sb concentration in GaAs_1-xSb_x modifies the energy band structure, effectively separating photogenerated electron-hole pairs. Increasing Sb concentration significantly boosts short circuit current density and power conversion efficiency. At x = 0.34, we achieve a short circuit current density (Jsc) of 28.3 mA·cm-2, an open-circuit voltage (Voc) of 0.93 V, and a 23.1% power-conversion efficiency (PCE) under AM 1.5G spectrum. Then, the distribution of electrons and holes in the transport process of the whole NWSCs is simulated when the Sb concentration is set to 0.34, which confirms electron separation to n-type GaAs and hole separation to p-type GaAs at x = 0.34, effectively. Moreover, the device exhibits an external quantum efficiency (EQE) of 95.9%.