Enhanced Light Absorption in Concentrated GaInP/GaAs/Ge Solar Cells Using a Secondary Optical Element with Subwavelength Structures

Abstract

A secondary optical element (SOE) with a subwavelength structure (SWS) was developed and incorporated on a GaInP/GaAs/Ge triple-junction solar cell. The nanoscale SWS was realized by dry etching using a silver (Ag) nanomask. The fabricated SWS SOE was mounted on a triple-junction solar cell. The SWS SOE exhibited improved transmittance in the broadband wavelength range from 350 to 1800 nm. Compared with SOE without SWS, the average transmittance was improved by 2.43%. The power-conversion efficiency (PCE) of the CPV module with the SWS SOE was 28.4%, whereas the PCE of the module without SWS was 27.8%. The enhanced efficiency of the CPV module is ascribed to improved current density due to reduced reflection losses at the surface of the SWS SOE.