Multi-Terminal Dual-Junction GaAs0.73P0.27/In0.22Ga0.78As Nanowire Solar Cell: An Integrated Approach to Simulation

A four-terminal dual-junction (2J) nanowire (NW) solar cell device concept is proposed and optimized via combined optoelectronic simulation using TCAD tools by Synopsys®. Rigorous coupled wave analysis (RCWA) was used for simulating absorption in GaAs0.73P0.27 and In0.22Ga0.78As NW arrays, while co-simulations in RSoft and Sentaurus was used to develop optimized core-shell NW diode parameters. It was shown that heterojunction designs comprising a wide-bandGaP emitter (GaP and GaAs for the top and bottom cells, respectively) is preferred for reduced impact of surface recombination velocity (SRV) as it promotes recovery of the open-circuit voltages by up to 30 mV and can achieve tandem device efficiency up to 27%. An experimental implementation of the stacked NW solar cell relying on the embedding of the NWs in flexible membranes and delamination of the arrays from the host substrate has been successfully developing. Owing to the versatility of this manufacturing method, the device can be enhanced with rear-side textured reflectors boosting the currents in the sub-cells.