Experimental Characterization and Optical Modelling of Absorption and Light Trapping in a-Si:H Solar Cells on Textured Tco

The quantitative description of the optical phenomena occuring in a-Si:H solar cells on textured substrates is a key issue to maximize the photovoltaic conversion efficiency. A semi-empirical numerical model is proposed taking into account the scattering induced by roughness at each interface of a multilayer structure. The scattered reflected and transmitted components are added to a classical matrix treatment of specular components. For each scattering angle, a new source beam is tracked in the subsequent layers. Light polarization and interference effects are properly taken into account and the energy deposited in each layer is derived. The model is tested on various structures and on a-Si:H p-i-n solar cells by angular-resolved reflectance and transmittance measurements and photothermal deflection spectroscopy.