Effects of sol-gel glass-based thin luminescence down-shifting layers with highly concentrated Zn-based semiconductor nanoparticles on quantum efficiencies of Si cells

Abstract We investigate the effects of luminescence down-shifting (LDS) layers made of Zn-based semiconductor nanoparticles (NPs) and sol-gel glass on the characteristics of Si cells. Impacts of the thickness of LDS layers and the concentration of NPs on internal quantum efficiencies (IQEs) of cells in the UV wavelength range are emphasized. The IQE at 350 nm is enhanced by ≈10% when the concentration of NPs increases by ≈ × 2 (from 1.1 × 10 16 to 2.4 × 10 16 cm −3 ) and the thickness of LDS layers decreases by ≈ × 0.5 (from 510 to ≈200 μ m). We numerically calculate the IQE by modeling the propagation of down-shifted photons in LDS layers, and find that the measured IQE is limited by the side escape loss and self-absorption of down-shifted photons. The IQE is assumed to be more enhanced by employing thinner LDS layers with higher concentrations of NPs such as layers fabricated using the layer-by-layer method.