Nanoimprint Photonic Crystal Film Enhanced Light-Trapping in a-Si Thin Film Solar Cells
We utilize photonic crystals to enhanced lighttrapping in a-Si:H thin film solar cells. The photonic crystals effectively increase Haze ratio of glass and decrease reflectance of a-Si:H solar cells. Therefore, increase the photon path length to obtain maximum absorption of the absorber layer. The photonic crystals can effective in harvesting weakly absorbing photons with energies just above the band edge. We were spin coated UV glue on the glass, and then nanoimprint of photonic crystals pattern. Finally, used UV lamp was curing of UV glue on the glass. When the 45∘composite photonic crystals structures, the haze was increase to 87.9 %, resulting the short circuit current density and efficiency increasing to 13.96 mA/cm2 and 7.39 %, respectively. Because 45∘composite photonic crystals easy to focus on the point of light lead to the effect of scattering can’t achieve. So, we designs 90∘V-shaped photonic crystals structures to increase scattering. When the 90∘V-shaped photonic crystals structures, the Haze was increase to 93.9 %. Therefore, the short circuit current density and Efficiency increasing to 15.62 mA/cm2 and 8.09 %, respectively. We observed ~35 % enhancement of the short-circuit current density and ~31 % enhancement of the conversion efficiency.
W. P. Chu et al., "Nanoimprint Photonic Crystal Film Enhanced Light-Trapping in a-Si Thin Film Solar Cells", Applied Mechanics and Materials, Vols. 110-116, pp. 497-502, 2012