Scalar scattering model of highly textured transparent conducting oxide

Abstract

Amorphous silicon solar cell is one of the most well developed solar energy solutions. In order to increase the energy conversion efficiency, light-trapping is necessary to the cell structure. Light trapping can be achieved by a textured transparent conducting oxide (TCO) layer and one of the critical factors of textured TCO is its haze value, which characterizes the scattering capability of the TCO. Recently several highly textured TCOs were presented with high haze at near IR region, where the haze of textured interfaces traditionally suffered from reduced scattering. However, suitable modeling is not established yet. In this work, we use scalar scattering theory and Kirchhoff approximation to solve haze value of complex surfaces analytically. Different from original Rayleigh scattering expression, this model illustrates intricacy between the surface roughness, correlation length, and the separation between different groups of height distributions. The resulting analytical formulation can be applied successfully not only in regular monotonically decaying spectral hazes but also various nonmonotonically shaped ones, meanwhile it retains important physical factors which can be useful for process evaluation. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3530684]