TY - JOUR

T1 - For none, one, or two polarities

T2 - How do POLO junctions fit best into industrial Si solar cells?

AU - Peibst, Robby

AU - Kruse, Christian

AU - Schäfer, Sören

AU - Mertens, Verena

AU - Bordihn, Stefan

AU - Dullweber, Thorsten

AU - Haase, Felix

AU - Hollemann, Christina

AU - Lim, Bianca

AU - Min, Byungsul

AU - Niepelt, Raphael

AU - Schulte-Huxel, Henning

AU - Brendel, Rolf

N1 - Funding information: We would like to thank Agnes Merkle for her contributions to the evaluation of screen?print metallization of p+ poly?Si and Audie Yeo and Boris Veith?Wolf for their contributions to the improvement of the AlO/SiN. We furthermore would like to thank Luise aus der Fünten for her help with TLM and PC?PLI measurements and L Menze for the optimization of in situ boron?doped and LPCVD?deposited polycrystalline Si. We would like to thank Larysa Mettner, Anja Mercker, Tobias Neubert, David Sylla, Ulrike Sonntag, Uwe Höhne, and Guido Glowatzki for sample processing. This work is funded by the German Federal Ministry for Economic Affairs and Energy under grant FKZ 0324274B (Genesis). 2 3 x We would like to thank Agnes Merkle for her contributions to the evaluation of screen-print metallization of p+ poly-Si and Audie Yeo and Boris Veith-Wolf for their contributions to the improvement of the Al2O3/SiNx. We furthermore would like to thank Luise aus der F?nten for her help with TLM and PC-PLI measurements and L Menze for the optimization of in situ boron-doped and LPCVD-deposited polycrystalline Si. We would like to thank Larysa Mettner, Anja Mercker, Tobias Neubert, David Sylla, Ulrike Sonntag, Uwe H?hne, and Guido Glowatzki for sample processing. This work is funded by the German Federal Ministry for Economic Affairs and Energy under grant FKZ 0324274B (Genesis).

PY - 2020/5/20

Y1 - 2020/5/20

N2 - We present a systematic study on the benefit of the implementation of poly-Si on oxide (POLO) or related junctions into p-type industrial Si solar cells as compared with the benchmark of Passivated Emitter and Rear Cell (PERC). We assess three aspects: (a) the simulated efficiency potential of representative structures with POLO junctions for none (=PERC+), one, and for two polarities; (b) possible lean process flows for their fabrication; and (c) experimental results on major building blocks. Synergistic efficiency gain analysis reveals that the exclusive suppression of the contact recombination for one polarity by POLO only yields moderate efficiency improvements between 0.23%abs and 0.41%abs as compared with PERC+ because of the remaining recombination paths. This problem is solved in a structure that includes POLO junctions for both polarities (POLO2), for whose realization we propose a lean process flow, and for which we experimentally demonstrate the most important building blocks. However, two experimental challenges—alignment tolerances and screen-print metallization of p+ poly-Si—are unsolved so far and reduced the efficiency of the “real” POLO2 cell as compared with an idealized scenario. As an intermediate step, we therefore work on a POLO IBC cell with POLO junctions for one polarity. It avoids the abovementioned challenges of the POLO2 structure, can be realized within a lean process flow, and has an efficiency benefit of 1.59%abs as compared with PERC—because not only contact recombination is suppressed but also the entire phosphorus emitter is replaced by an n+ POLO junction.

AB - We present a systematic study on the benefit of the implementation of poly-Si on oxide (POLO) or related junctions into p-type industrial Si solar cells as compared with the benchmark of Passivated Emitter and Rear Cell (PERC). We assess three aspects: (a) the simulated efficiency potential of representative structures with POLO junctions for none (=PERC+), one, and for two polarities; (b) possible lean process flows for their fabrication; and (c) experimental results on major building blocks. Synergistic efficiency gain analysis reveals that the exclusive suppression of the contact recombination for one polarity by POLO only yields moderate efficiency improvements between 0.23%abs and 0.41%abs as compared with PERC+ because of the remaining recombination paths. This problem is solved in a structure that includes POLO junctions for both polarities (POLO2), for whose realization we propose a lean process flow, and for which we experimentally demonstrate the most important building blocks. However, two experimental challenges—alignment tolerances and screen-print metallization of p+ poly-Si—are unsolved so far and reduced the efficiency of the “real” POLO2 cell as compared with an idealized scenario. As an intermediate step, we therefore work on a POLO IBC cell with POLO junctions for one polarity. It avoids the abovementioned challenges of the POLO2 structure, can be realized within a lean process flow, and has an efficiency benefit of 1.59%abs as compared with PERC—because not only contact recombination is suppressed but also the entire phosphorus emitter is replaced by an n+ POLO junction.

KW - efficiency potential

KW - passivating contacts

KW - POLO

KW - poly-Si

KW - solar cell development

UR - http://www.scopus.com/inward/record.url?scp=85074818856&partnerID=8YFLogxK

U2 - 10.1002/pip.3201

DO - 10.1002/pip.3201

M3 - Article

AN - SCOPUS:85074818856

VL - 28

SP - 503

EP - 516

JO - Progress in Photovoltaics: Research and Applications

JF - Progress in Photovoltaics: Research and Applications

SN - 1062-7995

IS - 6

ER -