ECN publication
Title:
N-type polysilicon passivating contacts for industrial bifacial n-pert cells
 
Author(s):
 
Published by: Publication date:
ECN Solar Energy 24-6-2016
 
ECN report number: Document type:
ECN-M--16-015 Conference Paper
 
Number of pages: Full text:
6 Download PDF  

Abstract:
We present a high-performance bifacial n-type solar cell with n+ polysilicon (polySi) back side passivating contacts and fire-through screen-printed metallization, processed on 6" Cz wafers. The cells were manufactured with low-cost industrial process steps yielding a best efficiency of 20.7%, and an average Voc of 674 mV. We analysed effects of variation of doping level, thickness, and oxide properties of the n-type polySi/SiOx layers, as well as hydrogenation from a PECVD SiNx:H coating, which led to recombination current densities down to ~2 fA/cm2 and ~4 fA/cm2 on planar and textured surface, respectively. The results are novel in four aspects: the cells are bifacial, they are full 6" size while employing LPCVD for the polySi deposition, the polySi passivating contact is metallized by fire-through screen printing paste, and hydrogenation is done by PECVD-deposited and fired SiNx:H. Analysis shows that the wafer bulk lifetime in the cell is high and that the Voc of the cell is limited by the Jo of the uniform diffused boron emitter and its contacts. Ways to improve the efficiency of the cell to > 22% are indicated.


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