TY - JOUR

T1 - On the chances and challenges of combining electron-collecting nPOLO and hole-collecting Al-p+ contacts in highly efficient p-type c-Si solar cells

AU - Peibst, Robby

AU - Haase, Felix

AU - Min, Byungsul

AU - Hollemann, Christina

AU - Brendemühl, Till

AU - Bothe, Karsten

AU - Brendel, Rolf

N1 - Funding Information: We would like to thank Anja Christ, Annika Raugewitz, Hilke Fischer,Magalie Pollmann, Renate Winter, Bianca Gehring, and ThomasFriedrich for sample processing and David Sylla and Tobias Neubert forlaser structuring andI–Vmeasurements. We furthermore would like tothank David Hinken, Dominic Walter, and Michael Rienäcker for valu-able discussions. Also, we would like to thank Raymond Zieseniß, GuidoGlowatzki and Jan Krügener from the Institute for Electronic Materialsand Devices of the Leibniz University Hannover for the excellent coop-eration and the supply of LPCVD-based poly-Si layers.We also thank TOYO Aluminium for providing the Al-paste,Heraeus and Dupont, for providing the Ag-pastes, and Longi for pro-viding the wafer material.This work was funded by the German Federal Ministry for Eco-nomic Affairs and Energy (BMWi) under contact number 0324275A(Street) and contact number 03EE1012A (NanoPERC), as well as bythe state of Lower Saxony. Open Access funding enabled and organized by Projekt DEAL.

PY - 2023/3/1

Y1 - 2023/3/1

N2 - ISFH is following a distinct cell development roadmap, which comprises—as a short-term concept—the combination of an n-type doped electron-collecting poly-Si on oxide (POLO) junction with an Al-alloyed p+ junction for hole collection. This combination can be integrated either in front- and back-contacted back junction cells (POLO-BJ) or in interdigitated back-contacted cells (POLO-IBC). Here, we present recent progress with these two cell concepts. We report on a certified M2-sized 22.9% efficient POLO-BJ cell with a temperature coefficient TCη of only −(0.3 ± 0.02) %rel/K and a certified 23.7% (4 cm2 d.a.) efficient POLO-IBC cell. We discuss various specific conceptual aspects of this technology and present a simulation-based sensitivity analysis for quantities related to the quality of the hole-collecting alloyed Al-p+ junction which are subject to continuous improvement and thus hard to predict exactly. We report that the measured pseudo fill factor values decrease more due to metallization than would be expected from recombination in the metallized regions with an ideality factor of one only. The gap to pseudo fill factor values that are theoretically achievable at the respective open-circuit voltages is 1.1%abs (Ga-doped wafer) for POLO-IBC and 1.4%abs (B-doped wafer) to 2%abs (Ga-doped wafer) for POLO-BJ. With an embedded blocking layer for Ag crystallites in the poly-Si, we present a concept to reduce this gap.

AB - ISFH is following a distinct cell development roadmap, which comprises—as a short-term concept—the combination of an n-type doped electron-collecting poly-Si on oxide (POLO) junction with an Al-alloyed p+ junction for hole collection. This combination can be integrated either in front- and back-contacted back junction cells (POLO-BJ) or in interdigitated back-contacted cells (POLO-IBC). Here, we present recent progress with these two cell concepts. We report on a certified M2-sized 22.9% efficient POLO-BJ cell with a temperature coefficient TCη of only −(0.3 ± 0.02) %rel/K and a certified 23.7% (4 cm2 d.a.) efficient POLO-IBC cell. We discuss various specific conceptual aspects of this technology and present a simulation-based sensitivity analysis for quantities related to the quality of the hole-collecting alloyed Al-p+ junction which are subject to continuous improvement and thus hard to predict exactly. We report that the measured pseudo fill factor values decrease more due to metallization than would be expected from recombination in the metallized regions with an ideality factor of one only. The gap to pseudo fill factor values that are theoretically achievable at the respective open-circuit voltages is 1.1%abs (Ga-doped wafer) for POLO-IBC and 1.4%abs (B-doped wafer) to 2%abs (Ga-doped wafer) for POLO-BJ. With an embedded blocking layer for Ag crystallites in the poly-Si, we present a concept to reduce this gap.

KW - efficiency potential

KW - passivating contacts

KW - POLO

KW - poly-Si

KW - solar cell development

KW - temperature coefficient

UR - http://www.scopus.com/inward/record.url?scp=85124985123&partnerID=8YFLogxK

U2 - 10.1002/pip.3545

DO - 10.1002/pip.3545

M3 - Article

AN - SCOPUS:85124985123

VL - 31

SP - 327

EP - 340

JO - Progress in Photovoltaics: Research and Applications

JF - Progress in Photovoltaics: Research and Applications

SN - 1062-7995

IS - 4

ER -