Broadband down-conversion based near infrared quantum cutting in Eu2+–Yb3+ co-doped SrAl2O4 for crystalline silicon solar cells

Abstract

Near infrared (NIR) quantum cutting involving the down conversion of an absorbed visible photon to emission of two NIR photons was achieved in SrAl2O4:0.01Eu2+, xYb3+ (x=0, 1, 2, 5, 10, 20, 30mol%) samples. The photoluminescence properties of samples in visible and NIR regions were measured to verify the energy transfer (ET) from Eu2+ to Yb3+. The results demonstrated that Eu2+ was an efficient sensitizer for Yb3+ in the SrAl2O4 host lattice. According to Gaussian fitting analysis and temperature-dependent luminescence experiments, the conclusion was drawn that the cooperative energy transfer (CET) process dominated the ET process and the influence of charge transfer state (CTS) of Yb3+ could be negligible. As a result, the high energy transfer efficiency (ETE) and quantum yield (QY) have been acquired, the maximum value approached 73.68% and 147.36%, respectively. Therefore, this down-conversion material has potential application in crystalline silicon solar cells to improve conversion efficiency.