Triple-junction InGaP/GaAs/Ge solar cells integrated with polymethyl methacrylate subwavelength structure

• Published in: Applied surface science Vol. 320; pp. 901 - 907
• Main Authors: Kim, Dae-Seon, Jeong, Yonkil, Jeong, Hojung, Jang, Jae-Hyung
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30.11.2014; Elsevier
• Subjects: Antireflection coating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Gallium arsenide; Gallium arsenides; Germanium; Photovoltaic; Photovoltaic cells; Physics; Polymethyl methacrylates; Solar cells; Subwavelength structure; Thin films; Titanium dioxide; Subwavelength structure; Antireflection coating; Photovoltaic; Solar cells; Gallium arsenides; Inorganic compounds; Semiconductor materials; Ternary compounds; Binary compounds; Gallium phosphide; Indium phosphide; Germanium; Antireflection coatings
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.09.138

•A high aspect ratio subwavelength structure was realized.•The subwavelength structure was integrated onto a triple-junction solar cell.•The fabricated subwavelength structure showed enhanced optical properties.•The power-conversion efficiency was greatly increased. GaAs-based triple-junction tandem solar cells incorporating an antireflection coating (ARC) consisting of a subwavelength structure (SWS) and bilayer thin films are reported. A high aspect ratio SWS was realized on polymethyl methacrylate (PMMA) using a two-step etched silicon template and a stamping method. The fabricated PMMA SWS consisting of a two-dimensional array of nanoscale needles with a period of 300nm and an aspect ratio exceeding 2.3 exhibited significantly improved optical performance. The average reflectance of the PMMA SWS was reduced from 7.1 to 4.4% as compared to that of the bare PMMA film, which resulted in an improvement of the transmittance from 90.7 to 92.9% in the wavelength range between 300 and 1700nm. By integrating the PMMA SWS together with a TiO2/Al2O3 bilayer AR coating onto the top of an InGaP/GaAs/Ge triple-junction solar cell, the surface reflection of the solar cell could be minimized. The integrated PMMA SWS on the bilayer thin film ARC enhanced the power-conversion efficiency (η) of the triple-junction solar cell from 30.2 to 31.6% and from 37.8 to 40.8% under 1 and 157 sun condition, respectively.