Simulation and development of sub-wavelength grated dielectric ARCs for CPV applications

Abstract

Here, and in an attempt to identify a better alternative to the conventional dual layer ARCs for III-V multi-junction concentrator cells operating with or without protective cover glass in conjunction with wide acceptance angles, we have undertaken a systematic analysis of design parameters and angular dependent antireflective properties of dielectric grating formed, through the implementation of sub-wavelength arrays of 2D pyramidal gratings of ZnS and TiO2. Though the study indicated no or limited improvement for devices operating with a SiO2 like cover glass, in the absence of a cover the evaluation indicates that through a careful selection of the design these dielectric gratings can reduce reflection-loss related current losses by 2-3 fold by comparison to their planar double layer ARC counterparts. i.e. for a 3J metamorphic device this lead to a current improvement of 0.7 mA/cm2 for a 60 degree acceptance angles.