TY - JOUR

T1 - Evolutionary PERC+ solar cell efficiency projection towards 24% evaluating shadow-mask-deposited poly-Si fingers below the Ag front contact as next improvement step

AU - Dullweber, Thorsten

AU - Stöhr, Maximilian

AU - Kruse, Christian

AU - Haase, Felix

AU - Rudolph, Martin

AU - Beier, Birgit

AU - Jäger, Philip

AU - Mertens, Verena

AU - Peibst, Robby

AU - Brendel, Rolf

N1 - Funding Information: We gratefully acknowledge the support by the German Federal Ministry for Economic Affairs and Energy under the contracts 0324294C and 0324246B . Publisher Copyright: © 2020 Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/8/1

Y1 - 2020/8/1

N2 - Monofacial PERC and bifacial PERC + solar cells have become the mainstream solar cell technology exhibiting conversion efficiencies around 22.5% in mass production. We determine a specific saturation current density J0,Ag = 1400 fA/cm2 of the screen-printed Ag front contact. When weighted with the contact area fraction of 3.0% the Ag metal contacts contribute 42 fA/cm2 to the total J0,total = 130 fA/cm2 thereby being a main limitation of the Voc. We investigate carrier selective poly-Si on oxide (POLO) fingers below the screen-printed Ag contacts of PERC + solar cells in order to minimize contact recombination. We name this solar cell PERC + POLO. Numerical simulations reveal that PERC + POLO cells exhibit an efficiency potential up to 24.1% which is 0.3%abs. higher compared to PERC + solar cells. In order to enable low-cost manufacturing of poly-Si fingers, we investigate for the first time the deposition of suitable a-Si fingers by plasma-enhanced chemical vapour deposition (PECVD) through a shadow mask in a vacuum chamber. We demonstrate a-Si fingers as narrow as 70 μm and as high as 250 nm. The parasitic deposition below the mask increases the a-Si finger width by less than 30 μm compared to the mask opening width. First test wafers demonstrate an implied Voc up to 716 mV of PECVD a-Si layers which are crystalized and doped in a subsequent POCl3 diffusion. Applying this process sequence, PERC + POLO cells could be manufactured with the established industrial PERC + process only adding the PECVD deposition of a-Si fingers through a shadow mask.

AB - Monofacial PERC and bifacial PERC + solar cells have become the mainstream solar cell technology exhibiting conversion efficiencies around 22.5% in mass production. We determine a specific saturation current density J0,Ag = 1400 fA/cm2 of the screen-printed Ag front contact. When weighted with the contact area fraction of 3.0% the Ag metal contacts contribute 42 fA/cm2 to the total J0,total = 130 fA/cm2 thereby being a main limitation of the Voc. We investigate carrier selective poly-Si on oxide (POLO) fingers below the screen-printed Ag contacts of PERC + solar cells in order to minimize contact recombination. We name this solar cell PERC + POLO. Numerical simulations reveal that PERC + POLO cells exhibit an efficiency potential up to 24.1% which is 0.3%abs. higher compared to PERC + solar cells. In order to enable low-cost manufacturing of poly-Si fingers, we investigate for the first time the deposition of suitable a-Si fingers by plasma-enhanced chemical vapour deposition (PECVD) through a shadow mask in a vacuum chamber. We demonstrate a-Si fingers as narrow as 70 μm and as high as 250 nm. The parasitic deposition below the mask increases the a-Si finger width by less than 30 μm compared to the mask opening width. First test wafers demonstrate an implied Voc up to 716 mV of PECVD a-Si layers which are crystalized and doped in a subsequent POCl3 diffusion. Applying this process sequence, PERC + POLO cells could be manufactured with the established industrial PERC + process only adding the PECVD deposition of a-Si fingers through a shadow mask.

KW - a-Si fingers

KW - Carrier selective contacts

KW - PERC

KW - PERC+

KW - POLO

KW - Shadow mask

KW - TOPCon

UR - http://www.scopus.com/inward/record.url?scp=85084371417&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2020.110586

DO - 10.1016/j.solmat.2020.110586

M3 - Article

AN - SCOPUS:85084371417

VL - 212

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

M1 - 110586

ER -