Sm3+-doped alkaline earth borate glasses as UV → visible photon conversion layer for solar cells

Intense multi-peak red fluorescence emissions of Sm3+ are exhibited in alkaline-earth borate (LKZBSB) glasses under UV radiation. The spontaneous emission probabilities A(rad) corresponding to the 4G(5/2) -> 6H(J) (J=5/2, 7/2, 9/2 and 11/2) transitions are derived to be 24.74, 129.72, 117.03 and 32.23 s(-1), respectively, and the relevant stimulated emission cross-sections sigma(em) are 0.77 x 10(-22), 4.46 x 10(-22), 5.05 x 10(-22) and 1.38 x 10(-22) cm(2), confirming the effectiveness of red luminescence in Sm3+-doped LKZBSB glasses. Quantitative characterization through the evaluation of absolute spectral parameters reveals that the quantum yield of Sm3+-doped LKZBSB glasses is as high as 13.29%. Furthermore, with the introduction of Ce3+, the effective excitation wavelength range and the emission intensity of Sm3+ in LKZBSB glasses are remarkably expanded and improved by a maximum sensitization factor of 9.02 in the UVB region. These results demonstrate that the present glass system has promising potential as an efficient UV -> visible photon conversion layer for the enhancement of solar cell efficiency, including appealing applications in outer space. (C) 2014 Elsevier B.V. All rights reserved.