A Broadband Light-Trapping Nanostructure for InGaP/GaAs Dual-Junction Solar Cells Using Nanosphere Lithography-Assisted Chemical Etching

Abstract

III–V-based multijunction solar cells have become the leading power generation technology for space applications due to their high power conversion efficiency and reliable performance in extraterrestrial environments. Thinning down the absorber layers of multijunction solar cells can considerably reduce the production cost and improve their radiation hardness. Recent advances in ultrathin GaAs single-junction solar cells suggest the development of light-trapping nanostructures to increase light absorption in optically thin layers within III–V-based multijunction solar cells. Herein, a novel and highly scalable nanosphere lithography-assisted chemical etching method to fabricate light-trapping nanostructures in InGaP/GaAs dual-junction solar cells is studied. Numerical models show that integrating the nanostructured Al₂O₃/Ag rear mirror significantly enhances the broadband absorption within the GaAs bottom cell. Results demonstrate that the light-trapping nanostructures effectively increase the short-circuit current density in GaAs bottom cells from 14.04 to 15.06 mA cm⁻². The simulated nanostructured InGaP/GaAs dual-junction structure shows improved current matching between the GaAs bottom cell and the InGaP top cell, resulting in 1.12x higher power conversion efficiency. These findings highlight the potential of light-trapping nanostructures to improve the performance of III-V-based multijunction photovoltaic systems, particularly for high-efficiency applications in space.