Enhanced conversion efficiency in nanocrystalline solar cells using optically functional patterns

• Optically functional patterns were fabricated by direct printing technique.
• The light absorption of solar cells was increased by the patterned Ag substrate.
• Current density of solar cells on patterned Ag increased by approximately 15.7%.
• The efficiency of solar cells on patterned Ag increased by 19.5%.

The lower conversion efficiency of nanocrystalline silicon (nc-Si:H) solar cells is a result of its lower photon absorption capability of nc-Si:H. To increase photon absorption of nc-Si:H, the Ag substrates were fabricated with optically functional patterns. Two types of patterns, with random and regular structures, were formed by direct imprint technology. Owing to these optically functional patterns, the scattering of reflected light at the surface of the patterned Ag was enhanced and the optical path became longer. Thus, a greater amount of photons was absorbed by the nc-Si:H layer. Compared to flat Ag (without a surface pattern), the light absorption value of the nc-Si:H layer with a random structure pattern was increased at wavelengths ranging from 600 to 1100 nm. In the case of the regular patterned Ag, the light absorption value of the nc-Si:H layer was higher than the flat Ag at 300 to 1100 nm. Subsequently, nc-Si:H solar cells constructed on the optically functional pattern exhibit a 15.7% higher Jsc value and a 19.5% higher overall conversion efficiency, compared to an identical solar cell on flat Ag.