High Efficiency Industrial p-type PERC and PERT Crystalline Silicon Solar Cells: Boron Junction Doping and Surface Passivation

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2020-06-23

Date

2020

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Mcode

Degree programme

Language

en

Pages

120 + app. 76

Series

Aalto University publication series DOCTORAL DISSERTATIONS, 89/2020

Abstract

As photovoltaic (PV) energy will gradually become one of the main renewable energy sources to replace conventional energy sources in the next decades, industry needs to pay attention to mass production of cost-efficient solar cells. At present, p-type crystalline silicon (c-Si) solar cell is the mainstream cell product in PV industry due to cost-efficiency. In p-type c-Si solar cells, industrial PERC (Passivated Emitter and Rear Cell) and PERT (Passivated Emitter and Rear Totally-diffused) cells are two potential candidates towards even higher cost-efficiency. To achive this, a systematic study is needed on both PERC and PERT cells from an industrial research perspective, which is the aim of this thesis.The first part of the thesis studies the industrial PERC cell. The key processes of Al2O3 passivation and screen-printing aluminium local back surface field, as well as integration of the entire PERC process are discussed, based on which a cost-efficient industrial PERC roadmap is presented. The loss mechanisms of cell efficiency and recombination are analyzed based on key characterizations combined with PC1D/PC2D simulations, and effective solutions are put forward to decrease these losses and thus to increase cell efficiency. The second part of the thesis presents a study on boron implanted junction, junction passivation and metal/p+-Si ohmic contact, as well as their application into the industrial p-PERT cells. Firstly, the focus is placed on the impact of junction profile and surface passivation on boron emitter quality, which can be influenced by implantation and anneal parameters. High-quality boron emitters passivated with in-situ grown SiO2 are obtained. Secondly, a novel junction passivation scheme using SiO2/Al2O3/SiNx is presented, which demonstrates effective passivation on both p+ and n+ emitters due to an excellent chemical passivation combined with a weak field-effect passivation. Then, an industrial roadmap for p-PERT is presented, which is based on fully ion implanted (boron and phosphorus) technology and the presented two junction passivation schemes. The cell results indicate that p-PERT cell using this roadmap is promising candidate for the PV industry. The final part of the thesis presents an outlook for a future roadmap extending the cell efficiency of industrial p-type c-Si solar cells towards and beyond 24%.

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Supervising professor

Savin, Hele, Prof., Aalto University, Department of Electronics and Nanoengineering, Finland

Keywords

aluminum oxide (Al2O3), boron junction, industrial crystalline silicon solar cells, ion implantation, surface passivation

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Parts

  • [Publication 1]: Haibing Huang, Jun Lv, Lichun Wang, JianBo Wang, Weicheng Zhu, Lisa Mandrelt, Jim Sullivan, Babak Adibi, Chris Smith, Hannu Laine, Hele Savin. An Extendible Beyond 20% Efficiency cost-Efficient Bifacial Cell Using Boron & Phosphorus Implantation Technology and Its Prospects for the Future Production. in: 42nd IEEE Photovoltaic Specialist Conference, New Orleans, 2015: pp. 1-6.
    DOI: 10.1109/PVSC.2015.7356059 View at publisher
  • [Publication 2]: Haibing Huang, Jun Lv, Yameng Bao, Rongwei Xuan, Shenghua Suna, Sami Sneck, Shuo Li, Chiara Modanese, Hele Savin, Aihua Wang, Jianhua Zhao. 20.8% Industrial PERC Solar Cell: ALD Al2O3 Rear Surface Passivation, Efficiency Loss Mechanisms Analysis and Roadmap to 24%, Solar Energy Materials and Solar Cells. 161 (2017) 14-30.
    DOI: 10.1016/j.solmat.2016.11.018 View at publisher
  • [Publication 3]: Haibing Huang, Jun Lv, Yameng Bao, Rongwei Xuan, Shenghua Suna, Sami Sneck, Shuo Li, Chiara Modanese, Hele Savin, Aihua Wang, Jianhua Zhao. Data of ALD Al2O3 rear surface passivation, Al2O3 PERC cell performance, and cell efficiency loss mechanisms of Al2O3 PERC cell, Data in Brief. 11 (2017) 19-26.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201705113917
    DOI: 10.1016/j.dib.2016.12.030 View at publisher
  • [Publication 4]: Haibing Huang, Jun Lv, Yameng Bao, Rongwei Xuan, Shenghua Suna, Sami Sneck, Shuo Li, Chiara Modanese, Hele Savin, Aihua Wang, Jianhua Zhao. Data of the recombination loss mechanisms analysis on Al2O3 PERC cell using PC1D and PC2D simulations, Data in Brief. 11 (2017) 27–31.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201704203632
    DOI: 10.1016/j.dib.2016.12.031 View at publisher
  • [Publication 5]: Haibing Huang, Lichun Wang, Lisa Mandrell, Chiara Modanese, Shenghua Sun, Jianbo Wang, Aihua Wang, Jianhua Zhao, Babak Adibi, Hele Savin. Boron Implanted Junction with In-situ Oxide Passivation and Application to p-PERT Bifacial Silicon Solar Cell, Physica Status Solidi A: Applications and Materials Science. 216-6 (2019) 1800414: 1-15.
    DOI: 10.1002/pssa.201800414 View at publisher
  • [Publication 6]: Haibing Huang, Chiara Modanese, Shenghua Sun, Guillaume von Gastrow, Jianbo Wang, Toni P. Pasanen, Shuo Li, Lichun Wang, Yameng Bao, Zhen Zhu, Sami Sneck, Hele Savin. Effective passivation of p+ and n+ emitter using SiO2/Al2O3/SiNx stacks: Surface passivation mechanisms and application to industrial p-PERT bifacial Si solar cells. Solar Energy Materials and Solar Cells. 186 (2018) 356–364.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201808214650
    DOI: 10.1016/j.solmat.2018.07.007 View at publisher

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