• Title/Summary/Keyword: TOPCon solar cell fabrication

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Design Optimization of the Front Side in n-Type TOPCon Solar Cell

  • Jeong, Sungjin;Kim, Hongrae;Kim, Sungheon;Dhungel, Suresh Kumar;Kim, Youngkuk;Yi, Junsin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.6
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    • pp.616-621
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    • 2022
  • Numerical simulation is a good way to predict the conversion efficiency of solar cells without a direct experimentation and to achieve low cost and high efficiency through optimizing each step of solar cell fabrication. TOPCon industrial solar cells fabricated with n-type silicon wafers on a larger area have achieved a higher efficiency than p-type TOPCon solar cells. Electrical and optical losses of the front surface are the main factors limiting the efficiency of the solar cell. In this work, an optimization of boron-doped emitter surface and front electrodes through numerical simulation using "Griddler" is reported. Through the analysis of the results of simulation, it was confirmed that the emitter sheet resistance of 150 Ω/sq along the front electrodes having a finger width of 20 ㎛, and the number of finger lines ~130 for silicon wafer of M6 size is an optimized technology for the front emitter surface of the n-type TOPCon solar cells that can be developed.

A Review on TOPCon Solar Cell Technology

  • Yousuf, Hasnain;Khokhar, Muhammad Quddamah;Chowdhury, Sanchari;Pham, Duy Phong;Kim, Youngkuk;Ju, Minkyu;Cho, Younghyun;Cho, Eun-Chel;Yi, Junsin
    • Current Photovoltaic Research
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    • v.9 no.3
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    • pp.75-83
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    • 2021
  • The tunnel oxide passivated contact (TOPCon) structure got more consideration for development of high performance solar cells by the introduction of a tunnel oxide layer between the substrate and poly-Si is best for attaining interface passivation. The quality of passivation of the tunnel oxide layer clearly depends on the bond of SiO in the tunnel oxide layer, which is affected by the subsequent annealing and the tunnel oxide layer was formed in the suboxide region (SiO, Si2O, Si2O3) at the interface with the substrate. In the suboxide region, an oxygen-rich bond is formed as a result of subsequent annealing that also improves the quality of passivation. To control the surface morphology, annealing profile, and acceleration rate, an oxide tunnel junction structure with a passivation characteristic of 700 mV or more (Voc) on a p-type wafer could achieved. The quality of passivation of samples subjected to RTP annealing at temperatures above 900℃ declined rapidly. To improve the quality of passivation of the tunnel oxide layer, the physical properties and thermal stability of the thin layer must be considered. TOPCon silicon solar cell has a boron diffused front emitter, a tunnel-SiOx/n+-poly-Si/SiNx:H structure at the rear side, and screen-printed electrodes on both sides. The saturation currents Jo of this structure on polished surface is 1.3 fA/cm2 and for textured silicon surfaces is 3.7 fA/cm2 before printing the silver contacts. After printing the Ag contacts, the Jo of this structure increases to 50.7 fA/cm2 on textured silicon surfaces, which is still manageably less for metal contacts. This structure was applied to TOPCon solar cells, resulting in a median efficiency of 23.91%, and a highest efficiency of 24.58%, independently. The conversion efficiency of interdigitated back-contact solar cells has reached up to 26% by enhancing the optoelectrical properties for both-sides-contacted of the cells.