Development of in-situ doped poly-SiOx passivating contacts for high-efficiency solar cells

Master thesis (2018)

Authors

P. Guo Electrical Engineering, Mathematics and Computer Science

Contributors

O. Isabella (supervisor 1)
G. Yang (supervisor 1)
Faculty
Electrical Engineering, Mathematics and Computer Science
Copyright: © 2018 Peiqing Guo
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Published Date

01-05-2018

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

Carrier-selective passivating contacts (CSPCs) is now a popular contact structure that effectively passivates the crystalline silicon (c-Si) surface as well as selectively extracts the specific type of charge carrier (electrons or holes). In this thesis work, we developed the CSPCs based on oxygen-alloyed polycrystalline silicon (poly-SiOx) passivating contacts, which shows less parasitic absorption compared with the polycrystalline silicon (poly-Si) passivating contacts.
In order to deploy poly-SiOx CSPCs in c-Si solar cells, we optimized the oxygen content, doping level, high-temperature annealing as well as the hydrogen passivation process. As a result, the excellent passivation for n-type poly-SiOx passivating contact on both flat surface (implied-VOC of 727 mV and J0 of 2.4 fA/cm2) and textured surface (implied-VOC of 723 mV and j0 of 6.9 fA/cm2) and for p-type poly-SiOx passivating contact on flat surface (implied-VOC of 709 mV and J0 of 13.9 fA/cm2) are obtained.
With the optimized poly-SiOx passivating contacts, the front and back contacted (FBC) solar cells were fabricated in this thesis. An excellent fill factor of 83.5% was obtained in the solar cell with front and rear poly-SiOx passivating contacts, indicating an efficient carrier transport and collection. An active area efficiency of 21.5% featuring Jsc of 40.8 mA/cm2 was measured on a front side textured FBC solar cell with the optimized poly-SiOx passivating contacts. It indicates the potential for achieving a conversion efficiency of above 23.0 % with the same cell configuration in the short term.