Open AccessAnalytical solution for haze values of aluminium-induced texture (AIT) glass superstrates for a-Si:H solar cells
Author(s) -
Nasim Sahraei,
Karen Forberich,
Selvaraj Venkataraj,
Armin G. Aberle,
Ian Marius Peters
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.000a53
Subject(s) - haze , materials science , optics , scattering , surface roughness , silicon , amorphous silicon , surface finish , aluminium , light scattering , absorption (acoustics) , solar cell , texture (cosmology) , composite material , crystalline silicon , optoelectronics , physics , meteorology , image (mathematics) , artificial intelligence , computer science
Light scattering at randomly textured interfaces is essential to improve the absorption of thin-film silicon solar cells. Aluminium-induced texture (AIT) glass provides suitable scattering for amorphous silicon (a-Si:H) solar cells. The scattering properties of textured surfaces are usually characterised by two properties: the angularly resolved intensity distribution and the haze. However, we find that the commonly used haze equations cannot accurately describe the experimentally observed spectral dependence of the haze of AIT glass. This is particularly the case for surface morphologies with a large rms roughness and small lateral feature sizes. In this paper we present an improved method for haze calculation, based on the power spectral density (PSD) function of the randomly textured surface. To better reproduce the measured haze characteristics, we suggest two improvements: i) inclusion of the average lateral feature size of the textured surface into the haze calculation, and ii) considering the opening angle of the haze measurement. We show that with these two improvements an accurate prediction of the haze of AIT glass is possible. Furthermore, we use the new equation to define optimum morphology parameters for AIT glass to be used for a-Si:H solar cell applications. The autocorrelation length is identified as the critical parameter. For the investigated a-Si:H solar cells, the optimum autocorrelation length is shown to be 320 nm.