Towards 28 %-efficient Si single-junction solar cells with better passivating POLO junctions and photonic crystals

authored by: R. Peibst, M. Rienäcker, Y. Larionova, N. Folchert, F. Haase, C. Hollemann, S. Wolter, J. Krügener, P. Bayerl, J. Bayer, M. Dzinnik, R. J. Haug, R. Brendel
Abstract: We conduct numerical device simulations to study to what extend poly-Si on oxide (POLO)² IBC solar cells can be optimized. In particular, we evaluate the benefit of the concept of photonic crystals (PCs) for “standard” cell thicknesses compatible with industrial wafer handling. We find that for our current surface passivation quality, implementing PCs and decreasing the wafer thickness down to 15 μm would increase the efficiency by „only“ 1% absolute due to limiting surface recombination losses. We deduce a high c-Si/SiO_x interface state density D_it of 2.9 × 10¹² eV⁻¹cm⁻² by analyzing special two-terminal IV measurements on small pads that contact the intact interfacial oxide between pinholes with our MarcoPOLO model. Consequently, we improve the hydrogenation process of our POLO junctions by an Al₂O₃/SiN_x/Al₂O₃ rear-side dielectric layer stack. For n-type POLO (p-type POLO) J₀ is reduced from 4 (10) fA/cm² down to 0.5 ± 0.3 (3.3 ± 0.7) fA/cm². For this improved surface passivation, our numerical device simulations predict an efficiency potential of 29.1% (27.8%) for POLO² IBC cells with (without) PCs for a standard thickness of 150 μm. This shows that the “practical limit” for Si solar cells with poly-Si on oxide-based passivating contact schemes is above 27%, and, in general, that the efficiency potential of Si single-junction cells is still far from being exhausted. The first implementation of the improved POLO junctions into cell precursors confirms the predicted improvement on the level of suns - implied open-circuit voltage curves.
Organisation(s): Institute of Electronic Materials and Devices
Institute of Solid State Physics
Nanostructures Section
Laboratory of Nano and Quantum Engineering
Solar Energy Section
QuantumFrontiers
External Organisation(s): Institute for Solar Energy Research (ISFH)
Type: Article
Journal: Solar Energy Materials and Solar Cells
Volume: 238
ISSN: 0927-0248
Publication date: 05.2022
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films
Sustainable Development Goals: SDG 7 - Affordable and Clean Energy
Electronic version(s): https://doi.org/10.1016/j.solmat.2021.111560 (Access: Closed)

BibTeX

@article{3e279acfce944a4c9c19ccc3248bf886,
title = "Towards 28 %-efficient Si single-junction solar cells with better passivating POLO junctions and photonic crystals",
abstract = "We conduct numerical device simulations to study to what extend poly-Si on oxide (POLO)2 IBC solar cells can be optimized. In particular, we evaluate the benefit of the concept of photonic crystals (PCs) for “standard” cell thicknesses compatible with industrial wafer handling. We find that for our current surface passivation quality, implementing PCs and decreasing the wafer thickness down to 15 μm would increase the efficiency by „only“ 1% absolute due to limiting surface recombination losses. We deduce a high c-Si/SiOx interface state density Dit of 2.9 × 1012 eV−1cm−2 by analyzing special two-terminal IV measurements on small pads that contact the intact interfacial oxide between pinholes with our MarcoPOLO model. Consequently, we improve the hydrogenation process of our POLO junctions by an Al2O3/SiNx/Al2O3 rear-side dielectric layer stack. For n-type POLO (p-type POLO) J0 is reduced from 4 (10) fA/cm2 down to 0.5 ± 0.3 (3.3 ± 0.7) fA/cm2. For this improved surface passivation, our numerical device simulations predict an efficiency potential of 29.1% (27.8%) for POLO2 IBC cells with (without) PCs for a standard thickness of 150 μm. This shows that the “practical limit” for Si solar cells with poly-Si on oxide-based passivating contact schemes is above 27%, and, in general, that the efficiency potential of Si single-junction cells is still far from being exhausted. The first implementation of the improved POLO junctions into cell precursors confirms the predicted improvement on the level of suns - implied open-circuit voltage curves.",
author = "R. Peibst and M. Rien{\"a}cker and Y. Larionova and N. Folchert and F. Haase and C. Hollemann and S. Wolter and J. Kr{\"u}gener and P. Bayerl and J. Bayer and M. Dzinnik and Haug, {R. J.} and R. Brendel",
note = "Funding Information: We would like to thank H. Fischer, S. Sp{\"a}tlich, R. Winter, A. Raugewitz,G. Glowatzki and R. Zieseniβ for sample processing, M. Wolf, A. Dietrich, R. Reineke-Koch for discussion and support with the measurement systems, and Sajeev John for fruitful discussions. This work is funded by the German Ministry for Economic Affairs and Energy (grant FKZ 003EE1056A ), by the federal state of Lower Saxony and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy - EXC-2123 QuantumFrontiers – 390837967. ",
year = "2022",
month = may,
doi = "10.1016/j.solmat.2021.111560",
language = "English",
volume = "238",
journal = "Solar Energy Materials and Solar Cells",
issn = "0927-0248",
publisher = "Elsevier BV",
}