Veröffentlichungen
2018 |
|
R. Brendel, C. Kruse, A. Merkle, and R. Peibst Screening Selective Contact Material Combinations for Novel Crystalline Si Cell Structures Inproceedings WIP (Hrsg.): Proceedings of the 35th European Photovoltaic Solar Energy Conference and Exhibition, 39-46, Brussels, Belgium, (2018). Abstract | Links | BibTeX | Schlagwörter: Carrier Selective Contacts, laser processing, loss analysis, poly Si, selective contact, selectivity, Silicon Solar Cell(s) @inproceedings{Brendel2018,
title = {Screening Selective Contact Material Combinations for Novel Crystalline Si Cell Structures}, author = {R Brendel and C Kruse and A Merkle and R Peibst}, editor = {WIP}, doi = {10.4229/35thEUPVSEC20182018-1AO.2.6}, year = {2018}, date = {2018-09-24}, booktitle = {Proceedings of the 35th European Photovoltaic Solar Energy Conference and Exhibition}, pages = {39-46}, address = {Brussels, Belgium}, abstract = {High efficiency crystalline Si solar cells require contacts with high carrier selectivity. This is ensured for contacts having low recombination currents as well as low contact resistances. A large variety of material systems for electron- and hole-selective contacts were measured in the literature. We screen a subset of electron- and hole-selective contacts to find promising combinations in terms of efficiency potential on the one hand and in terms of practical processes on the other hand. We use modelling of ideal Si cells with non-ideal experimental contact properties to determine the maximum efficiency and the optimized areal contact fractions for many contact combinations. Cells using a-Si and/or poly-Si contacts have the highest contact-limited efficiencies. Such cells are, however, quite different from today’s PERC technology. We therefore also look for contact combinations that have one contact type equal to the current PERC technology and identify cell structures that combine a poly-Si(n) contact with a screen-printed Al-doped contacts (PAL cells) as an attractive upgrade for the PERC technology. We also report on experimental work on building blocks for various types of PAL cells.}, keywords = {Carrier Selective Contacts, laser processing, loss analysis, poly Si, selective contact, selectivity, Silicon Solar Cell(s)}, pubstate = {published}, tppubtype = {inproceedings} } High efficiency crystalline Si solar cells require contacts with high carrier selectivity. This is ensured for contacts having low recombination currents as well as low contact resistances. A large variety of material systems for electron- and hole-selective contacts were measured in the literature. We screen a subset of electron- and hole-selective contacts to find promising combinations in terms of efficiency potential on the one hand and in terms of practical processes on the other hand. We use modelling of ideal Si cells with non-ideal experimental contact properties to determine the maximum efficiency and the optimized areal contact fractions for many contact combinations. Cells using a-Si and/or poly-Si contacts have the highest contact-limited efficiencies. Such cells are, however, quite different from today’s PERC technology. We therefore also look for contact combinations that have one contact type equal to the current PERC technology and identify cell structures that combine a poly-Si(n) contact with a screen-printed Al-doped contacts (PAL cells) as an attractive upgrade for the PERC technology. We also report on experimental work on building blocks for various types of PAL cells.
|
2017 |
|
M. Rienäcker, M. Bossmeyer, A. Merkle, U. Römer, F. Haase, J. Krügener, R. Brendel, and R. Peibst IEEE Journal of Photovoltaics 7 (1), 11-18, (2017), ISSN: 2156-3381. Abstract | Links | BibTeX | Schlagwörter: Aluminum, Back-junction back-contact (BJBC) cells, boron, Conductivity, contact resistivity, Current density, Junctions, Photovoltaic cells, polysilicon, polysilicon on oxide (POLO) junctions, recombination, selective contacts, selectivity @article{Rienäcker2017b,
title = {Junction resistivity of carrier-selective polysilicon on oxide junctions and its impact on solar cell performance}, author = {M Rienäcker and M Bossmeyer and A Merkle and U Römer and F Haase and J Krügener and R Brendel and R Peibst}, doi = {10.1109/JPHOTOV.2016.2614123}, issn = {2156-3381}, year = {2017}, date = {2017-01-01}, journal = {IEEE Journal of Photovoltaics}, volume = {7}, number = {1}, pages = {11-18}, abstract = {We investigate the junction resistivity of high-quality carrier-selective polysilicon on oxide (POLO) junctions with the transfer length method. We demonstrate n+ POLO junctions with a saturation current density JC,poly of 6.2 fA/cm2 and a junction resistivity ρc of 0.6 mΩcm2, counterdoped n+ POLO junctions with 2.7 fA/cm2 and 1.3 mΩcm2, and p+ POLO junctions with 6.7 fA/cm2 and 0.2 mΩcm2. Such low junction resistivities and saturation current densities correspond to excellent selectivities S10 of up to 16.2. The efficiency potential for back-junction back-contact solar cells with these POLO junctions was determined to be larger than 25 % by numerical device simulations. We demonstrate experimentally a back-junction back-contact solar cell with p-type and n-type POLO junctions with an independently confirmed efficiency of 24.25 %.}, keywords = {Aluminum, Back-junction back-contact (BJBC) cells, boron, Conductivity, contact resistivity, Current density, Junctions, Photovoltaic cells, polysilicon, polysilicon on oxide (POLO) junctions, recombination, selective contacts, selectivity}, pubstate = {published}, tppubtype = {article} } We investigate the junction resistivity of high-quality carrier-selective polysilicon on oxide (POLO) junctions with the transfer length method. We demonstrate n+ POLO junctions with a saturation current density JC,poly of 6.2 fA/cm2 and a junction resistivity ρc of 0.6 mΩcm2, counterdoped n+ POLO junctions with 2.7 fA/cm2 and 1.3 mΩcm2, and p+ POLO junctions with 6.7 fA/cm2 and 0.2 mΩcm2. Such low junction resistivities and saturation current densities correspond to excellent selectivities S10 of up to 16.2. The efficiency potential for back-junction back-contact solar cells with these POLO junctions was determined to be larger than 25 % by numerical device simulations. We demonstrate experimentally a back-junction back-contact solar cell with p-type and n-type POLO junctions with an independently confirmed efficiency of 24.25 %.
|
2016 |
|
R. Brendel, M. Rienaecker, and R. Peibst A quantitative measure for the carrier selectivity of contacts to solar cells Inproceedings WIP (Hrsg.): Proceedings of the 32nd European Photovoltaic Solar Energy Conference, 447-451, Munich, Germany, (2016), ISBN: 3-936338-41-8. Abstract | Links | BibTeX | Schlagwörter: Carrier Selective Contacts, loss analysis, selectivity, Silicon Solar Cell(s) @inproceedings{Brendel2016,
title = {A quantitative measure for the carrier selectivity of contacts to solar cells}, author = {R Brendel and M Rienaecker and R Peibst}, editor = {WIP}, doi = {10.4229/EUPVSEC20162016-2CO.4.1}, isbn = {3-936338-41-8}, year = {2016}, date = {2016-09-01}, booktitle = {Proceedings of the 32nd European Photovoltaic Solar Energy Conference}, journal = {Proceedings of the 32nd European Photovoltaic Solar Energy Conference}, pages = {447-451}, address = {Munich, Germany}, abstract = {We discuss a physically motivated definition for a quantitative measure of the selectivity of electron and hole contacts. We define the selectivity S10 = log10(Vth /(c ×Jc)) to depend on the contact resistance c, the recombination current density Jc of the contact, and the thermal voltage Vth. A high selectivity relies on a highly asymmetric equilibrium carrier concentration of majority and minority carriers in the contact. The maximum efficiency max increases with the selectivity S10. This increase is linear until the efficiency starts to be limited by radiative recombination. We give analytic equations for calculating the maximum efficiency max(S10) of a crystalline Si cell that is ideal except for either one or two contacts. Achieving the maximum efficiency max requires optimized areal fractions fe,max and fh,max for the electron and the hole contacts, respectively . We give analytic equations for these contact fractions. }, keywords = {Carrier Selective Contacts, loss analysis, selectivity, Silicon Solar Cell(s)}, pubstate = {published}, tppubtype = {inproceedings} } We discuss a physically motivated definition for a quantitative measure of the selectivity of electron and hole contacts. We define the selectivity S10 = log10(Vth /(c ×Jc)) to depend on the contact resistance c, the recombination current density Jc of the contact, and the thermal voltage Vth. A high selectivity relies on a highly asymmetric equilibrium carrier concentration of majority and minority carriers in the contact. The maximum efficiency max increases with the selectivity S10. This increase is linear until the efficiency starts to be limited by radiative recombination. We give analytic equations for calculating the maximum efficiency max(S10) of a crystalline Si cell that is ideal except for either one or two contacts. Achieving the maximum efficiency max requires optimized areal fractions fe,max and fh,max for the electron and the hole contacts, respectively . We give analytic equations for these contact fractions.
|