Broadband excited Nd3+ NIR emission in Sr5(PO4)3Cl:Eu2+, Nd3+ phosphor for solar spectral modification

Abstract

Luminescence down-conversion is an excellent spectral conversion process to minimize the spectral mismatch between the incident solar radiation and the spectral response of a semiconductor (crystalline silicon (c-Si)) solar cells. For this purpose, we are proposing a novel near-infrared emitting Sr5(PO4)3Cl:Eu2+, Nd3+ phosphor prepared by solid state reaction. The prepared material has been characterized by using XRD, photoluminescence excitation (PLE), photoluminescence (PL) and fluorescence decay spectral measurements. The material shows a strong broadband excitation of Eu2+ in the wavelength range of 200–450 nm along with an intense Nd3+ NIR emission around 1000 nm which is favorable for solar spectrum modification. The PLE and PL spectra suggest that sensitization of Nd3+ NIR emission is possible via a strong 4f→5d transition of Eu2+ in Sr5(PO4)3Cl phosphor. We have also investigated the energy-transfer (ET) phenomenon occurring between the sensitizer (Eu2+) and activator (Nd3+) using fluorescence decay measurements. The results suggest that Eu2+-Nd3+ co-doped Sr5(PO4)3Cl phosphor with broad excitation band in the UV-blue region and intense NIR emission around 1 μm is aptly suitable as luminescent down converter useful crystalline silicon (c-Si) solar cells.