TY - GEN
T1 - Optimization of In-situ and Ex-situ doped p+ Passivating Contact for High Efficiency p-TOPCon Solar Cell Application
AU - Choi, Wook Jin
AU - Madani, Keeya
AU - Huang, Ying Yuan
AU - Jain, Aditi
AU - Ok, Young Woo
AU - Upadhyaya Min Gu Kang, Vijaykumar D.
AU - Choi, Sungjin
AU - Rohatgi, Ajeet
N1 - Publisher Copyright:
© 2021 IEEE.
PY - 2021/6/20
Y1 - 2021/6/20
N2 - This paper presents fabrication and optimization of p+ passivating contact (p+ poly-Si/SiOx/c-Si) for high efficiency p-TOPCon solar cells. The p+ passivating contacts were formed by (i) in-situ doped p+ poly-Si via LPCVD and (ii) ex-situ doping of intrinsic poly-Si via APCVD boron diffusion. We studied the relationship between the passivation quality of this contact as a function of boron diffusion profile varied by altering (i) the crystallization annealing temperature, and (ii) the APCVD precursor gas flow ratio \left( {{\emptyset _{{B_2}{H_6}}}/{\emptyset _{Si{H_4}}}} \right). In-situ doping resulted in higher B concentration in poly-Si, which improves field induced passivation, as well as in Si absorber near the interface, which enhances Auger recombination to degrade passivation. This trade-off resulted in lower optimum annealing temperature for in-situ process (875°C vs 950°C). However, process optimization resulted in excellent passivation with comparable iVoc and J0 for both in-situ (719mV/6.3fAcm-2) and ex-situ doped (716mV/6.6fAcm-2) un-metallized p-TOPCon. Greater than 22.0% screen-printed large area (244.32cm2) bifacial p-TOPCon solar cells were fabricated by replacing LBSF of p-PERC cells with 270 nm p+ TOPCon junction with 10% metal coverage on the rear side. TOPCon cells gave 0.4% higher efficiency than their PERC counterpart.
AB - This paper presents fabrication and optimization of p+ passivating contact (p+ poly-Si/SiOx/c-Si) for high efficiency p-TOPCon solar cells. The p+ passivating contacts were formed by (i) in-situ doped p+ poly-Si via LPCVD and (ii) ex-situ doping of intrinsic poly-Si via APCVD boron diffusion. We studied the relationship between the passivation quality of this contact as a function of boron diffusion profile varied by altering (i) the crystallization annealing temperature, and (ii) the APCVD precursor gas flow ratio \left( {{\emptyset _{{B_2}{H_6}}}/{\emptyset _{Si{H_4}}}} \right). In-situ doping resulted in higher B concentration in poly-Si, which improves field induced passivation, as well as in Si absorber near the interface, which enhances Auger recombination to degrade passivation. This trade-off resulted in lower optimum annealing temperature for in-situ process (875°C vs 950°C). However, process optimization resulted in excellent passivation with comparable iVoc and J0 for both in-situ (719mV/6.3fAcm-2) and ex-situ doped (716mV/6.6fAcm-2) un-metallized p-TOPCon. Greater than 22.0% screen-printed large area (244.32cm2) bifacial p-TOPCon solar cells were fabricated by replacing LBSF of p-PERC cells with 270 nm p+ TOPCon junction with 10% metal coverage on the rear side. TOPCon cells gave 0.4% higher efficiency than their PERC counterpart.
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U2 - 10.1109/PVSC43889.2021.9518759
DO - 10.1109/PVSC43889.2021.9518759
M3 - Conference contribution
AN - SCOPUS:85115953552
T3 - Conference Record of the IEEE Photovoltaic Specialists Conference
SP - 1907
EP - 1912
BT - 2021 IEEE 48th Photovoltaic Specialists Conference, PVSC 2021
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 48th IEEE Photovoltaic Specialists Conference, PVSC 2021
Y2 - 20 June 2021 through 25 June 2021
ER -