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

• The absorption spectrum of Eu2+ ion is strong in intensity and broad in bandwidth.
• The spectra of Eu2+ in SrAl2O4 lies in the strongest region of solar spectrum.
• The cooperative energy transfer (CET) dominated the energy transfer process.
• The domination of CET is confirmed by experimental analysis.
• SrAl2O4:Eu2+,Yb3+ show high energy transfer efficiency and long lifetime.

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, 30 mol%) 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.

Near infrared quantum cutting was achieved in Eu2+–Yb3+ co-doped SrAl2O4 samples. The cooperative energy transfer process dominated energy transfer process and high energy transfer efficiency was acquired.Figure optionsDownload as PowerPoint slide