TY - JOUR
T1 - Contact resistivity of the p-Type amorphous silicon hole contact in silicon heterojunction solar cells
AU - Leilaeioun, Mehdi Ashling
AU - Weigand, William
AU - Boccard, Mathieu
AU - Yu, Zhengshan J.
AU - Fisher, Kathryn
AU - Holman, Zachary C.
N1 - Funding Information:
Manuscript received May 23, 2019; revised August 28, 2019; accepted October 9, 2019. Date of publication November 27, 2019; date of current version December 23, 2019. This work was supported in part by the Engineering Research Center Program of the National Science Foundation and in part by the Office of Energy Efficiency and Renewable Energy of the Department of Energy under NSF Cooperative Agreement EEC-1041895. (Mehdi (Ashling) Leilaeioun and William Weigand contributed equally to this work.) (Corresponding author: Zachary Holman).
Publisher Copyright:
© 2011-2012 IEEE.
PY - 2020/1
Y1 - 2020/1
N2 - In silicon heterojunction solar cells made with high-lifetime wafers, resistive losses in the contacts dominate the total electrical power loss. Moreover, it is widely believed that the hole contact stack - a-Si:H(i)/a-Si:H(p)/ITO/Ag - is responsible for more of this power loss than the electron contact stack. In this article, we vary the a-Si:H(i) layer thickness, the a-Si:H(p) layer thickness and doping, and the indium tin oxide (ITO) doping, and determine the effect of each variation on the contact resistivity of the hole contact stack. In addition, we make complete solar cells with the same variations and correlate their series resistivity to the hole contact resistivity. We find that the contact resistivity is most sensitive to the thickness of the a-Si:H(i) layer and the oxygen partial pressure during ITO sputtering. Increasing the former from 4 to 16 nm results in a fourfold increase in contact resistivity, whereas increasing the latter from 0.14 to 0.85 mTorr raises the contact resistivity almost 30-fold. Optimized conditions produce a contact resistivity of 0.10 Ωcm2, while maintaining an implied open-circuit voltage of 720 mV measured on cell precursors, which is the lowest contact resistivity value reported in the literature for an a-Si:H hole contact.
AB - In silicon heterojunction solar cells made with high-lifetime wafers, resistive losses in the contacts dominate the total electrical power loss. Moreover, it is widely believed that the hole contact stack - a-Si:H(i)/a-Si:H(p)/ITO/Ag - is responsible for more of this power loss than the electron contact stack. In this article, we vary the a-Si:H(i) layer thickness, the a-Si:H(p) layer thickness and doping, and the indium tin oxide (ITO) doping, and determine the effect of each variation on the contact resistivity of the hole contact stack. In addition, we make complete solar cells with the same variations and correlate their series resistivity to the hole contact resistivity. We find that the contact resistivity is most sensitive to the thickness of the a-Si:H(i) layer and the oxygen partial pressure during ITO sputtering. Increasing the former from 4 to 16 nm results in a fourfold increase in contact resistivity, whereas increasing the latter from 0.14 to 0.85 mTorr raises the contact resistivity almost 30-fold. Optimized conditions produce a contact resistivity of 0.10 Ωcm2, while maintaining an implied open-circuit voltage of 720 mV measured on cell precursors, which is the lowest contact resistivity value reported in the literature for an a-Si:H hole contact.
KW - Amorphous silicon
KW - carrier-selective contact
KW - contact resistivity
KW - passivating contact
KW - silicon heterojunction (SHJ)
KW - solar cell
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U2 - 10.1109/JPHOTOV.2019.2949430
DO - 10.1109/JPHOTOV.2019.2949430
M3 - Article
AN - SCOPUS:85076024703
SN - 2156-3381
VL - 10
SP - 54
EP - 62
JO - IEEE Journal of Photovoltaics
JF - IEEE Journal of Photovoltaics
IS - 1
M1 - 8915757
ER -