Dual-mode optical thermometer and spectral conversion for c-Si solar cells in Ag clusters and Yb 3+ co-doped borate glasses

Borate glasses doped with Ag clusters and Yb3+ were prepared using the conventional melt-quenching method. Fluorescence spectra and decay curve measurements confirmed that energy transfer (ET) occurred from the Ag clusters to Yb3+. The fluorescent glasses can convert ultraviolet light to visible-infrared region which matches well with the spectral response of c-Si solar cells to improve the conversion efficiency. The lifetimes of Ag clusters decreased in Ag clusters mono-doped and Ag clusters/Yb3+ co-doped glasses as the temperature increased. Sensitivity values based on the fluorescence lifetime (FL) were calculated. Furthermore, a high optical sensitivity based on the fluorescence intensity ratio (FIR) technology and the maximum absolute sensitivity (Sa) and relative sensitivity (Sr) were 4.79 % K- 1 and 0.97 % K-1, respectively. Temperature cycling tests demonstrated the repeatability of the luminescence. These results indicate that this fluorescent glass can serve as an excellent temperature sensing material.