Broadband Antireflection and Light Trapping in Thin Film Silicon Solar Cells With Hemisphere Arrays

An efficient photon management scheme for high-performance thin film solar cells requires both antireflection and light trapping. In this letter, we propose a double-sided grating design, by patterning hemispherical pit arrays (HPAs) on the front and back surfaces of glass substrates, to satisfy such a dual requirements. The HPAs are designed with different period sizes on the two sides: For one thing, the large-sized hemisphere arrays placed at the top surface allow multiple rebounds of incident light, thereby suppressing reflection. For another, wavelength-sized arrays on the bottom side provide strong diffraction scattering and, then, trap photons inside the cell devices. Electromagnetic simulations show that a-Si:H solar cells incorporated with the double-sided configuration gain a significant enhancement in spectral response from 600 to 800 nm, as well as the photo-generated current is improved by 21.76% compared with the random textured reference solar cells.