Regular Article

The design of broad band anti-reflection coatings for solar cell applications

Centre for Advanced Studies in Electronics Science and Technology, School of Physics, University of Hyderabad, 500046 Hyderabad, Telangana, India

^a e-mail: mgksp@uohyd.ac.in

Received: 8 October 2016
Revised: 17 December 2016
Accepted: 3 January 2017
Published online: 27 January 2017

Abstract

The design of broadband anti-reflection coatings (ARCs) for solar cell applications using multiobjective differential evolutionary (MODE) algorithms is reported. The effect of thickness and refractive index contrast within the layers of the ARC on the bandwidth of reflectance is investigated in detail. In the case of the hybrid plasmonic ARC structures the effect of size, shape and filling fraction of silver (Ag) nanoparticles on the reflectance is studied. Bandwidth is defined as the spectral region of wavelengths over which the reflectance is below 2%. Single, two and three layers ARCs (consisting of MgF₂, Al₂O₃, Si₃N_4, TiO₂ and ZnS or combinations of these materials) were simulated for performance evaluation on an a-Si photovoltaic cell. It is observed that the three layer ARC consisting of MgF₂/Si₃N₄/TiO₂(ZnTe) of 81/42/36 nm thicknesses, respectively, exhibited a weighted reflectance of 1.9% with a bandwidth of 450 nm over the wavelength range of 300–900 nm. The ARC bandwidth could be further improved by embedding randomly distributed Ag nanoparticles of size between 100 and 120 nm on a two layer ARC consisting of Al₂O₃/TiO₂ with thickness of 42 nm and 56 nm respectively. This plasmon-dielectric hybrid ARC design exhibited a weighted reflectance of 0.6% with a bandwidth of 560 nm over the wavelength range of 300–900 nm.