In order to reduce thermal loss due to spectral mismatch of the solar cell absorption, the quantum cutting with Tb3+-Er3+ couples as spectral converters is experimentally observed. One high energy ultraviolet photon(7F6 → 5L1 of Tb3+) is quantumly cut into two lower energy photons: one is in near-infrared(4I9/2 → 4I15 of Er3+) and the other in blue region(5D4 → 7F6 of Tb3+), both of which can be efficiently absorbed by solar cells. A quantum efficiency, ηQE of up to 188% is calculated which is close to the theoretical limit of 200%. The energy mismatch in the energy transfer from Tb3+(5L1 → 5D4)to Er3+(4I9/2 → 4I15/2) is 237 cm-1, less than a phonon energy of 400 cm-1 in NaYF4, making the energy transfer nearly resonant. The energy migration among Tb3+ donors is treated approximately by the diffusion model and the initial process of energy transfer among the Tb3+-Er3+ couples is found to be dipole-dipole interactions.
CITATION STYLE
Liu, C. X., Wang, P. C., Luo, Y. S., & Wang, L. J. (2011). Tb3+-Er3+ couples as spectral converters in NaYF4 for GaAs solar cells. Faguang Xuebao/Chinese Journal of Luminescence, 32(11), 1120–1125. https://doi.org/10.3788/fgxb20113211.1120
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