Broadband antireflective coatings for high efficiency InGaP/GaAs/InGaAsP/InGaAs multi-junction solar cells

Abstract

Design and fabrication of antireflection coatings (ARCs) was performed to maximize the photocurrent of Ⅲ-Ⅴ solar cells based on InGaP, GaAs, InGaAsP, and InGaAs. The current-limiting behavior of multi-junction solar cells allowed only the specific design of ARCs to improve the total current density of multi-junction solar cells, which enabled thin and efficient antireflection layers to achieve their full potential. ARCs were designed for InGaP/GaAs and InGaAsP/InGaAs double junction solar cells and InGaP/GaAs/InGaAsP/InGaAs quadruple junction solar cells. From the ARC design results, the best solar cell reflectance at the region of interest appeared to be 1.44% for InGaP/GaAs solar cells, 2.17% for InGaAsP/InGaAs, and 0.48% for the quadruple junction solar cells. To achieve the preferred refractive index for the ARC structures, nanostructures fabricated via glancing angle deposition were utilized. With ARC fabricated structures, InGaP/GaAs double junction solar cells yielded a power conversion efficiency of 13.3%, which was 1.34 times higher than that of cells without ARC (9.91%). Additionally, calculation results for the various ARC designs using dual and triple material systems were provided to increase their applicability.