Title:	Quantifying the Antireflection Properties of Internal Interfaces of Solar Cells on Rough TCO
Author(s):	V. Hagemann, S. Reichel, S. Bauer, P. Lechner
Keywords:	Oblique Incident Sunlight, Transparent Conducting Oxides (TCO), Texturisation, Texturization
Topic:	Thin Films
Subtopic:	Amorphous and Microcrystalline Silicon
Event:	23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain
Session:	3AV.2.16
Pages:	2400 - 2402
ISBN:	3-936338-24-8
Paper DOI:	10.4229/23rdEUPVSEC2008-3AV.2.16
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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Transparent conductive oxides (TCOs) are crucial for the performance of amorphous, microcrystalline and micromorph, silicon based thin film solar cells. Key properties of TCO coated substrates are high conductivity, high transmission and good light trapping ability. However, another important, but less prominent effect of the surface roughness is the grading of the otherwise abrupt index step at the interface of layers with different refractive indices. This results in a reduction of the effective reflection compared to the Fresnel-reflection of a step index interface. The purpose of this work is to describe an algorithm that allows for quantifying these reflection reducing properties of internal interfaces of solar cells on rough TCOs. This will result in a deeper understanding of the optical properties of TCO substrates and their effect on the efficiency of solar cells. It will especially be helpful to give a physical meaning to parameters that are used in the semi-coherent modeling. A reflection reduction of 30%-60% for the air – TCO interface of commercially available TCO substrates was calculated. For the TCO – a-Si:H (p) interface the calculated reflection reduction is still in the range of 10% to 20%.