Dual-mode downconversion luminescence with broad near-ultraviolet and blue light excitation in Tm3+/Yb3+ codoped oxy-fluoride glasses for c-Si solar cells

In this work, we demonstrated an efficient dual-mode solar spectral converter Tm3+/Yb3+ co-doped oxyfluoride glasses synthesized using high temperature melt-quenching method. The transmittance, photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra and decay dynamics have been systematically investigated. The experimental results revealed that two distinct solar spectral converting processes, quantum cutting (QC) and down-shifting (DS) were achieved through the sensitization of Tm3+ excited multiplets and a broad band attributing to Yb3+-O2- charge transfer state (CTS), respectively. The prepared materials could convert the UV (250-370 nm) and blue (450-490 nm) photons into broad NIR emission (900-1100nm), which coincides well with the most efficient spectral response of Si-based solar cells. The resultant Tm3+/Yb3+ co-doped oxy-fluoride glasses with dual-mode solar spectral modification indicate its potential application in improving the energy conversion efficiency of Si-based solar cells.