Near-infrared quantum cutting in Bi~(3+)/Yb~(3+) co-doped oxyfluoride glasses via cooperative energy transfer for solar cells

摘要

The Bi~(3+)/Yb~(3+) ion co-doped 55SiO_2-20Al_2O_3-5Na_2CO_3-20CaF_2 glasses are synthesized successfully by a conventional melting-quenching method. High efficient quantum cutting involving the emission of two near-infrared photons for one ultraviolet photon absorbed is realized in the oxyfluoride glasses co-doped with Bi~(3+) and Yb~(3+). An intense characteristic near-infrared emission around 977 nm of Yb~(3+):~2F_(5/2) → ~2F_(7/2) transition is obtained when the 303 nm is as excitation wavelength to induce the ~1S_0 → ~3P_1 transition of Bi~(3+). The maximum quantum efficiency of our glasses is estimated to be 164.3%. The energy transfer mechanism is proposed to be a cooperative energy transfer via second-order down-conversion process. The glasses could be a potential quantum cutting converter to improve the photovoltaic energy conversion efficiency of crystalline Si solar cells via spectrum modification.