Enhancing conversion efficiency of crystalline silicon photovoltaic modules through luminescent down-shifting by using Eu3+-Zn2+complexes

Abstract

Currently commercial silicon-based solar cells are usually absorbing only a narrow band of sunlight within the visible light range; thus, their conversion efficiency is low. This challenge has been partially improved by using up-converting or down-converting luminescent materials. Amongst those materials, rare earth luminescent materials doped with other rare earth elements have been developed and demonstrated significant improvement of conversion efficiency. This work reports a novel complex Zn0.4Eu0.6(TTA)2phenCl0.6 (named Eu–Zn in short) that have been synthesized through divalent Zn2+ doping into a trivalent Eu3+ luminescent Eu(TTA)3phen matrix. The properties of the Eu–Zn compound have been characterized by using Inductively Coupled Plasma (ICP)-Atomic Emission spectrum, Fourier Transform Infrared (FTIR), Ultraviolet–Visible (UV–Vis) and Photoluminescence (PL) Spectra. The Eu–Zn complex is further integrated in poly(methyl methacrylate) (PMMA) thin films through solution casting and the composite thin film has lower luminescent quantum yield than that of the Eu–Zn complex alone. The Eu–Zn/PMMA composite film as a down-converting luminescent coating layer is constructed in monocrystalline silicon (MCSi, active area of 156 cm2) and polycrystalline silicon (PCSi, active area of 100 cm2) solar cell modules. The external quantum efficiency (EQE) of both MCSi and PCSi modules shows a decrease in the range of 370–400 nm with the increase of Eu–Zn concentration. The conversion efficiency of MCSi cell is improved by 0.37% (from 14.37% to 14.74%) with the concentration of Eu–Zn at 1%.