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

The Bi3+/Yb3+ ion co-doped 55SiO(2)-20Al(2)O(3)-5Na(2)CO(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 Bi3+ and Yb3+. An intense characteristic near-infrared emission around 977 nm of Yb3+:F-2(5/2) -> F-2(7/2) transition is obtained when the 303 nm is as excitation wavelength to induce the S-1(0) -> P-3(1) 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. (C) 2014 Elsevier B.V. All rights reserved.