Title:	Quantifying Internal Optical Losses for 21% n-Si Rear Junction Cells
Author(s):	F. Duerinckx, M. Aleman, P. Choulat, I. Kuzma-Filipek, E. Cornagliotti, J. Szlufcik
Keywords:	Optical Losses, Silicon-Nitride, SiO2, n-Type
Topic:	WAFER-BASED SILICON SOLAR CELLS AND MATERIALS TECHNOLOGY
Subtopic:	Silicon Solar Cell Characterisation and Modelling
Event:	29th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2BO.2.3
Pages:	417 - 420
ISBN:	3-936338-34-5
Paper DOI:	10.4229/EUPVSEC20142014-2BO.2.3
Price:	0,00 EUR
Document(s):	paper, presentation

Abstract/Summary:

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This work deals with quantifying the internal optical losses in a Cu plated n-Si rear junction cell. The focus is on the following 2 losses : (i) Free Carrier Absorption (FCA) in the highly doped regions of the device and (ii) non-ideal internal reflectance at the rear of the device. For the FCA, optical measurements have been used to quantify the loss of photons in both the n+ diffused Front Surface Field (FSF) and p+ emitter regions of the device. It is shown that this loss is negligible for the P- and B-doped layers used in imec’s n-Si rear junction cells and amounts to a combined loss in short-circuit current of only 0.1 mA/cm2. External reflectance measurements have also been employed to quantify the internal rear reflectance in the device as function of the nature and thickness of the rear dielectric layers. Predictive calculations indicate an improved internal rear reflectance by switching from the original dielectric stack (thermal oxide + PECVD nitride) to a single dielectric layer (> 100nm thermal oxide), which has been confirmed experimentally. Such implementation into imec’s n-Si rear junction cells has helped to improve the efficiency to levels above 21%.