Near-infrared quantum cutting in Bi3+/Yb3+ co-doped oxyfluoride glasses via cooperative energy transfer for solar cells

• Highly efficient Bi3+ excitation and Yb3+ NIR emission was demonstrated in oxyfluoride glass.
• Bi3+/Yb3+ dual ion high efficient quantum cutting was observed.
• The cooperative energy transfer process from Bi3+ to Yb3+ was discussed.
• The proposed glasses will favor the development of the crystalline Si solar cells.

The Bi3+/Yb3+ ion co-doped 55SiO2–20Al2O3–5Na2CO3–20CaF2 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 Bi3+ and Yb3+. An intense characteristic near-infrared emission around 977 nm of Yb3+:2F5/2 → 2F7/2 transition is obtained when the 303 nm is as excitation wavelength to induce the 1S0 → 3P1 transition of Bi3+. 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.