Veröffentlichungen
2020 |
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M. Müller, B. Wolpensinger, B. Min, G. Fischer, P. Palinginis, and D. H. Neuhaus IEEE Journal of Photovoltaics 10 (6), 1642-1647, (2020). Links | BibTeX | Schlagwörter: ocal back-surface-field (LBSF) thickness, open-circuit voltage ANOVA, Passivated emitter and rear cell (PERC) solar cells, Silicon solar cell @article{Müller2020,
title = {Impact of Local Back-Surface-Field Thickness on Open-Circuit Voltage in PERC Solar Cells: An Experimental Study Applying ANOVA to Determine Critical Sample Size Necessary to Differentiate Mean LBSF Values With Statistical Significance}, author = {M Müller and B Wolpensinger and B Min and G Fischer and P Palinginis and D H Neuhaus}, doi = {10.1109/JPHOTOV.2020.3026978}, year = {2020}, date = {2020-11-01}, journal = {IEEE Journal of Photovoltaics}, volume = {10}, number = {6}, pages = {1642-1647}, keywords = {ocal back-surface-field (LBSF) thickness, open-circuit voltage ANOVA, Passivated emitter and rear cell (PERC) solar cells, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } |
2018 |
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F. Haase, J. Käsewieter, S. R. Nabavi, E. Jansen, R. Rolfes, and M. Köntges IEEE Journal of Photovoltaics 8 (6), 1510-1524, (2018), ISSN: 2156-3381. Abstract | Links | BibTeX | Schlagwörter: Crack, mechanical loading, photovoltaic (PV) module, Silicon solar cell @article{Haase2018c,
title = {Fracture Probability, Crack Patterns, and Crack Widths of Multicrystalline Silicon Solar Cells in PV Modules During Mechanical Loading}, author = {F Haase and J Käsewieter and S R Nabavi and E Jansen and R Rolfes and M Köntges}, doi = {10.1109/JPHOTOV.2018.2871338}, issn = {2156-3381}, year = {2018}, date = {2018-11-01}, journal = {IEEE Journal of Photovoltaics}, volume = {8}, number = {6}, pages = {1510-1524}, abstract = {We experimentally analyze the position and opening behavior of cracks in multicrystalline silicon solar cells laminated in standard-sized frameless modules during mechanical loading in a 4-line-bending setup. The results of the experiment are reproduced by simulations for a standard module. These simulations open the opportunity to simulate also complex load situations. Cell interconnect ribbons have big influence to which critically extended module can be bended until a crack appears. Modules with cell interconnect ribbons that are parallel to the bending axis can be bended four times less until cell cracking than modules with cell interconnect ribbons oriented perpendicular to the bending axis and two times less compared with a module without cell interconnect ribbons. Small edge cracks parallel to the bending axis and cross cracks at the busbar decrease the critical bending in the module by a factor of four compared to small edge cracks perpendicular to the bending axis and crack-free cells. The presence of the backsheet decreases the crack width during mechanical loading by 30% compared to a module without a backsheet. In the standard module, the crack width of a single crack is 3.4 μm at loads comparable to the IEC 61215 5400 Pa test.}, keywords = {Crack, mechanical loading, photovoltaic (PV) module, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } We experimentally analyze the position and opening behavior of cracks in multicrystalline silicon solar cells laminated in standard-sized frameless modules during mechanical loading in a 4-line-bending setup. The results of the experiment are reproduced by simulations for a standard module. These simulations open the opportunity to simulate also complex load situations. Cell interconnect ribbons have big influence to which critically extended module can be bended until a crack appears. Modules with cell interconnect ribbons that are parallel to the bending axis can be bended four times less until cell cracking than modules with cell interconnect ribbons oriented perpendicular to the bending axis and two times less compared with a module without cell interconnect ribbons. Small edge cracks parallel to the bending axis and cross cracks at the busbar decrease the critical bending in the module by a factor of four compared to small edge cracks perpendicular to the bending axis and crack-free cells. The presence of the backsheet decreases the crack width during mechanical loading by 30% compared to a module without a backsheet. In the standard module, the crack width of a single crack is 3.4 μm at loads comparable to the IEC 61215 5400 Pa test.
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H. Schulte-Huxel, D. J. Friedman, and A. C. Tamboli String-Level Modeling of Two, Three, and Four Terminal Si-Based Tandem Modules Artikel IEEE Journal of Photovoltaics 8 (5), 1370-1375, (2018). Abstract | Links | BibTeX | Schlagwörter: module interconnection, Multijunction solar cells, Silicon solar cell, tandem device @article{Schulte-Huxel2018b,
title = {String-Level Modeling of Two, Three, and Four Terminal Si-Based Tandem Modules}, author = {H Schulte-Huxel and D J Friedman and A C Tamboli}, doi = {10.1109/JPHOTOV.2018.2855104}, year = {2018}, date = {2018-09-01}, journal = {IEEE Journal of Photovoltaics}, volume = {8}, number = {5}, pages = {1370-1375}, abstract = {III-V/Si tandem solar cells have demonstrated efficiencies exceeding the theoretical efficiency limit of silicon solar cells. On the cell level, device modeling shows that three-terminal tandem (3T) devices with rear contacted bottom Si cells perform as well as operating the subcells independently (4T). However, integrating these 3T devices in a module requires voltage matching of the top and the bottom cell. Here, we investigate the robustness of parallel/series-interconnected 3T III-V/Si tandem devices in comparison with series-interconnected two terminal (2T) and independently operated (4T) devices with respect to spectral, thermal, and resistive effects. Under most conditions, interconnected 3T devices are able to perform as well as those with independent operation of the top and bottom cell, and 3T devices significantly outperform 2T devices.}, keywords = {module interconnection, Multijunction solar cells, Silicon solar cell, tandem device}, pubstate = {published}, tppubtype = {article} } III-V/Si tandem solar cells have demonstrated efficiencies exceeding the theoretical efficiency limit of silicon solar cells. On the cell level, device modeling shows that three-terminal tandem (3T) devices with rear contacted bottom Si cells perform as well as operating the subcells independently (4T). However, integrating these 3T devices in a module requires voltage matching of the top and the bottom cell. Here, we investigate the robustness of parallel/series-interconnected 3T III-V/Si tandem devices in comparison with series-interconnected two terminal (2T) and independently operated (4T) devices with respect to spectral, thermal, and resistive effects. Under most conditions, interconnected 3T devices are able to perform as well as those with independent operation of the top and bottom cell, and 3T devices significantly outperform 2T devices.
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R. Peibst, Y. Larionova, S. Reiter, T. F. Wietler, N. Orlowski, S. Schäfer, B. Min, M. Stratmann, D. Tetzlaff, J. Krügener, U. Höhne, J. D. Kähler, H. Mehlich, S. Frigge, and R. Brendel IEEE Journal of Photovoltaics 8 (3), 719-725, (2018), ISSN: 2156-3381. Abstract | Links | BibTeX | Schlagwörter: Carrier Selective Contacts, passivation, Polycrystalline silicon, Silicon solar cell, transparent conductive oxide, Zinc oxide @article{Peibst2018,
title = {Building Blocks for Industrial, Screen-Printed Double-Side Contacted POLO Cells With Highly Transparent ZnO:Al Layers}, author = {R Peibst and Y Larionova and S Reiter and T F Wietler and N Orlowski and S Schäfer and B Min and M Stratmann and D Tetzlaff and J Krügener and U Höhne and J D Kähler and H Mehlich and S Frigge and R Brendel}, doi = {10.1109/JPHOTOV.2018.2813427}, issn = {2156-3381}, year = {2018}, date = {2018-05-01}, journal = {IEEE Journal of Photovoltaics}, volume = {8}, number = {3}, pages = {719-725}, abstract = {We report on an industrial large area, screen-printed, double-side contacted cell with polysilicon on oxide (POLO) junctions on both sides and an energy conversion efficiency of 22.3% (A = 244.15 cm 2, Voc = 714 mV, FF = 81.1%, Jsc = 38.5 mA/cm2, measured in-house). This cell shows an extraordinarily low series resistance below 0.05 Ω cm2. This confirms the low specific junction resistance observed recently for POLO junctions. The present cell suffers from 1) low short-circuit current due to parasitic absorption in the rather thick poly-Si (30 nm), as well as in the indium tin oxide, 2) deterioration of the recombination behavior upon sputter deposition of a transparent conductive oxide (TCO), and 3) shunts near the edge due to nonadapted TCO edge exclusion. We address all of these limitations experimentally. In particular, we developed a plasma-enhanced chemical vapor deposition process for ZnO:Al, which does not compromise the passivation of the POLO junctions underneath. An estimation of the efficiency potential (based on the two-diode model and the assumption that all these building blocks can be successfully combined on a cell level) shows that 25.3% can be achieved with this cell concept. We also look into potential cost advantages of the POLO junction scheme for this cell structure, such as the usage of p-type Cz-Si material and the omission of Ag fingers.}, keywords = {Carrier Selective Contacts, passivation, Polycrystalline silicon, Silicon solar cell, transparent conductive oxide, Zinc oxide}, pubstate = {published}, tppubtype = {article} } We report on an industrial large area, screen-printed, double-side contacted cell with polysilicon on oxide (POLO) junctions on both sides and an energy conversion efficiency of 22.3% (A = 244.15 cm 2, Voc = 714 mV, FF = 81.1%, Jsc = 38.5 mA/cm2, measured in-house). This cell shows an extraordinarily low series resistance below 0.05 Ω cm2. This confirms the low specific junction resistance observed recently for POLO junctions. The present cell suffers from 1) low short-circuit current due to parasitic absorption in the rather thick poly-Si (30 nm), as well as in the indium tin oxide, 2) deterioration of the recombination behavior upon sputter deposition of a transparent conductive oxide (TCO), and 3) shunts near the edge due to nonadapted TCO edge exclusion. We address all of these limitations experimentally. In particular, we developed a plasma-enhanced chemical vapor deposition process for ZnO:Al, which does not compromise the passivation of the POLO junctions underneath. An estimation of the efficiency potential (based on the two-diode model and the assumption that all these building blocks can be successfully combined on a cell level) shows that 25.3% can be achieved with this cell concept. We also look into potential cost advantages of the POLO junction scheme for this cell structure, such as the usage of p-type Cz-Si material and the omission of Ag fingers.
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2017 |
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J. Krügener, F. Haase, M. Rienäcker, R. Brendel, H. J. Osten, and R. Peibst Solar Energy Materials and Solar Cells 173 , 85-91, (2017), ISSN: 0927-0248, (Proceedings of the 7th international conference on Crystalline Silicon Photovoltaics). Abstract | Links | BibTeX | Schlagwörter: Carrier lifetime, Gettering, passivating contact, POLO, polysilicon, Silicon solar cell, solar cell @article{Krügener2017b,
title = {Improvement of the SRH bulk lifetime upon formation of n-type POLO junctions for 25% efficient Si solar cells}, author = {J Krügener and F Haase and M Rienäcker and R Brendel and H J Osten and R Peibst}, doi = {10.1016/j.solmat.2017.05.055}, issn = {0927-0248}, year = {2017}, date = {2017-12-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {173}, pages = {85-91}, abstract = {Carrier-selective contact schemes, like polysilicon on oxide (POLO), provide low contact resistivities while preserving an excellent passivation quality. These junctions offer an important additional feature compared to a-Si/c-Si heterojunctions. We find that the formation of n-type POLO junctions lead to a huge increase of the Shockley-Read-Hall (SRH) lifetime of the substrate, a prerequisite for highly efficient solar cells. The SRH lifetime improvement can be observed for both bulk polarities and for a variety of bulk resistivities. Thus we suggest that the highly doped POLO junction getters impurities that have more or less symmetric SRH capture cross sections. We are able to achieve SRH lifetimes of > 50 ms. By applying POLO junctions to interdigitated back contact cells, we achieve cells with an efficiency of 25%.}, note = {Proceedings of the 7th international conference on Crystalline Silicon Photovoltaics}, keywords = {Carrier lifetime, Gettering, passivating contact, POLO, polysilicon, Silicon solar cell, solar cell}, pubstate = {published}, tppubtype = {article} } Carrier-selective contact schemes, like polysilicon on oxide (POLO), provide low contact resistivities while preserving an excellent passivation quality. These junctions offer an important additional feature compared to a-Si/c-Si heterojunctions. We find that the formation of n-type POLO junctions lead to a huge increase of the Shockley-Read-Hall (SRH) lifetime of the substrate, a prerequisite for highly efficient solar cells. The SRH lifetime improvement can be observed for both bulk polarities and for a variety of bulk resistivities. Thus we suggest that the highly doped POLO junction getters impurities that have more or less symmetric SRH capture cross sections. We are able to achieve SRH lifetimes of > 50 ms. By applying POLO junctions to interdigitated back contact cells, we achieve cells with an efficiency of 25%.
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V. Titova, B. Veith-Wolf, D. Startsev, and J. Schmidt Energy Procedia 124 (Supplement C), 441 - 447, (2017), ISSN: 1876-6102, (7th International Conference on Silicon Photovoltaics, SiliconPV 2017, 3-5 April 2017, Freiburg, Germany). Abstract | Links | BibTeX | Schlagwörter: atomic layer deposition, electron-selective contact, Silicon solar cell, surface passivation, Titanium oxide @article{Titova2017b,
title = {Effective passivation of crystalline silicon surfaces by ultrathin atomic-layer-deposited TiOx layers}, author = {V Titova and B Veith-Wolf and D Startsev and J Schmidt}, doi = {10.1016/j.egypro.2017.09.272}, issn = {1876-6102}, year = {2017}, date = {2017-09-21}, journal = {Energy Procedia}, volume = {124}, number = {Supplement C}, pages = {441 - 447}, abstract = {We characterize the surface passivation properties of ultrathin titanium oxide (TiOx) films deposited by atomic layer deposition (ALD) on crystalline silicon by means of carrier lifetime measurements. We compare different silicon surface treatments prior to TiOx deposition, such as native silicon oxide (SiOy), chemically grown SiOy and thermally grown SiOy. The best passivation quality is achieved with a native SiOy grown over 4 months and a TiOx layer thickness of 5 nm, resulting in an effective lifetime of 1.2 ms on 1.3 Ωcm p-type float-zone silicon. The measured maximum lifetime corresponds to an implied open-circuit voltage (iVoc) of 710 mV. For thinner TiOx layers the passivation quality is reduced, however, samples passivated with only 2 nm of TiOx still show a lifetime of 612 μs and an iVoc of 694 mV. The contact resistivity of the TiOx including the SiOy interlayer between the silicon wafer and the TiOx is below 0.8 Ωcm2. The combination of excellent surface passivation and low contact resistivity has the potential for silicon solar cells with efficiencies exceeding 26%.}, note = {7th International Conference on Silicon Photovoltaics, SiliconPV 2017, 3-5 April 2017, Freiburg, Germany}, keywords = {atomic layer deposition, electron-selective contact, Silicon solar cell, surface passivation, Titanium oxide}, pubstate = {published}, tppubtype = {article} } We characterize the surface passivation properties of ultrathin titanium oxide (TiOx) films deposited by atomic layer deposition (ALD) on crystalline silicon by means of carrier lifetime measurements. We compare different silicon surface treatments prior to TiOx deposition, such as native silicon oxide (SiOy), chemically grown SiOy and thermally grown SiOy. The best passivation quality is achieved with a native SiOy grown over 4 months and a TiOx layer thickness of 5 nm, resulting in an effective lifetime of 1.2 ms on 1.3 Ωcm p-type float-zone silicon. The measured maximum lifetime corresponds to an implied open-circuit voltage (iVoc) of 710 mV. For thinner TiOx layers the passivation quality is reduced, however, samples passivated with only 2 nm of TiOx still show a lifetime of 612 μs and an iVoc of 694 mV. The contact resistivity of the TiOx including the SiOy interlayer between the silicon wafer and the TiOx is below 0.8 Ωcm2. The combination of excellent surface passivation and low contact resistivity has the potential for silicon solar cells with efficiencies exceeding 26%.
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Y. Larionova, M. Turcu, S. Reiter, R. Brendel, D. Tetzlaff, J. Krügener, T. Wietler, U. Höhne, J-D. Kähler, and R. Peibst physica status solidi (a) 214 (8), 1700058, (2017), ISSN: 1862-6319, (1700058). Abstract | Links | BibTeX | Schlagwörter: passivating contact, passivation, polysilicon, Silicon solar cell @article{Larionova2017,
title = {On the recombination behavior of p+-type polysilicon on oxide junctions deposited by different methods on textured and planar surfaces}, author = {Y Larionova and M Turcu and S Reiter and R Brendel and D Tetzlaff and J Krügener and T Wietler and U Höhne and J-D Kähler and R Peibst}, doi = {10.1002/pssa.201700058}, issn = {1862-6319}, year = {2017}, date = {2017-08-01}, journal = {physica status solidi (a)}, volume = {214}, number = {8}, pages = {1700058}, abstract = {We investigate the passivation quality of hole‐collecting junctions consisting of thermally or wet‐chemically grown interfacial oxides, sandwiched between a monocrystalline‐Si substrate and a p‐type polycrystalline‐silicon (Si) layer. The three different approaches for polycrystalline‐Si preparation are compared: the plasma‐enhanced chemical vapor deposition (PECVD) of in situ p+‐type boron‐doped amorphous Si layers, the low pressure chemical vapor deposition (LPCVD) of in situ p+‐type B‐doped polycrystalline Si layers, and the LPCVD of intrinsic amorphous Si, subsequently ion‐implanted with boron. We observe the lowest J0e values of 3.8 fA cm−2 on thermally grown interfacial oxide on planar surfaces for the case of intrinsic amorphous Si deposited by LPCVD and subsequently implanted with boron. Also, we obtain a similar high passivation of p+‐type poly‐Si junctions on wet‐chemically grown oxides as well as for all the investigated polycrystalline‐Si deposition approaches. Conversely, on alkaline‐textured surfaces, J0e is at least 4 times higher compared to planar surfaces. This finding holds for all the junction preparation methods investigated. We show that the higher J0e on textured surfaces can be attributed to a poorer passivation of the p+ poly/c‐Si stacks on (111) when compared to (100) surfaces. }, note = {1700058}, keywords = {passivating contact, passivation, polysilicon, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } We investigate the passivation quality of hole‐collecting junctions consisting of thermally or wet‐chemically grown interfacial oxides, sandwiched between a monocrystalline‐Si substrate and a p‐type polycrystalline‐silicon (Si) layer. The three different approaches for polycrystalline‐Si preparation are compared: the plasma‐enhanced chemical vapor deposition (PECVD) of in situ p+‐type boron‐doped amorphous Si layers, the low pressure chemical vapor deposition (LPCVD) of in situ p+‐type B‐doped polycrystalline Si layers, and the LPCVD of intrinsic amorphous Si, subsequently ion‐implanted with boron. We observe the lowest J0e values of 3.8 fA cm−2 on thermally grown interfacial oxide on planar surfaces for the case of intrinsic amorphous Si deposited by LPCVD and subsequently implanted with boron. Also, we obtain a similar high passivation of p+‐type poly‐Si junctions on wet‐chemically grown oxides as well as for all the investigated polycrystalline‐Si deposition approaches. Conversely, on alkaline‐textured surfaces, J0e is at least 4 times higher compared to planar surfaces. This finding holds for all the junction preparation methods investigated. We show that the higher J0e on textured surfaces can be attributed to a poorer passivation of the p+ poly/c‐Si stacks on (111) when compared to (100) surfaces.
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H. Schulte-Huxel, R. Witteck, H. Holst, M. R. Vogt, S. Blankemeyer, D. Hinken, T. Brendemühl, T. Dullweber, K. Bothe, M. Köntges, and R. Brendel IEEE Journal of Photovoltaics 7 (1), 25-31, (2017), ISSN: 2156-3381. Abstract | Links | BibTeX | Schlagwörter: cell interconnection, Current measurement, loss analysis, Optical interconnections, Optical losses, passivated emitter and rear cell (PERC), photovoltaic (PV) module, Photovoltaic cells, Photovoltaic systems, ray tracing, Resistance, Silicon solar cell, Standards @article{Schulte-Huxel2016,
title = {High-efficiency modules with passivated emitter and rear solar cells an analysis of electrical and optical losses*}, author = {H Schulte-Huxel and R Witteck and H Holst and M R Vogt and S Blankemeyer and D Hinken and T Brendemühl and T Dullweber and K Bothe and M Köntges and R Brendel}, doi = {10.1109/JPHOTOV.2016.2614121}, issn = {2156-3381}, year = {2017}, date = {2017-01-01}, journal = {IEEE Journal of Photovoltaics}, volume = {7}, number = {1}, pages = {25-31}, abstract = {We process a photovoltaic (PV) module with 120 half passivated emitter and rear cells that exhibits an independently confirmed power of 303.2 W and a module efficiency of 20.2% (aperture area). The cells are optimized for operation within the module. We enhance light harvesting from the inactive spacing between the cells and the cell interconnect ribbons. Additionally, we reduce the inactive area to below 3% of the aperture module area. The impact of these measures is analyzed by ray-tracing simulations of the module. Using a numerical model, we analyze and predict the module performance based on the individual cell measurements and the optical simulations. We determine the power loss due to series interconnection of the solar cells to be 1.5%. This is compensated by a gain in current of 1.8% caused by the change of the optical environment of the cells in the module. We achieve a good agreement between simulations and experiments, both showing no cell-to-module power loss.}, keywords = {cell interconnection, Current measurement, loss analysis, Optical interconnections, Optical losses, passivated emitter and rear cell (PERC), photovoltaic (PV) module, Photovoltaic cells, Photovoltaic systems, ray tracing, Resistance, Silicon solar cell, Standards}, pubstate = {published}, tppubtype = {article} } We process a photovoltaic (PV) module with 120 half passivated emitter and rear cells that exhibits an independently confirmed power of 303.2 W and a module efficiency of 20.2% (aperture area). The cells are optimized for operation within the module. We enhance light harvesting from the inactive spacing between the cells and the cell interconnect ribbons. Additionally, we reduce the inactive area to below 3% of the aperture module area. The impact of these measures is analyzed by ray-tracing simulations of the module. Using a numerical model, we analyze and predict the module performance based on the individual cell measurements and the optical simulations. We determine the power loss due to series interconnection of the solar cells to be 1.5%. This is compensated by a gain in current of 1.8% caused by the change of the optical environment of the cells in the module. We achieve a good agreement between simulations and experiments, both showing no cell-to-module power loss.
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2016 |
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R. Brendel, T. Dullweber, R. Peibst, C. Kranz, A. Merkle, and D. Walter Breakdown of the efficiency gap to 29% based on experimental input data and modelling Artikel Progress in Photovoltaics: Research and Applications 24 (12), 1475-1486, (2016). Abstract | Links | BibTeX | Schlagwörter: conductive boundary model, IBC, interdigitated back-contacted cell, loss analysis, passivated emitter and rear cell, PERC, Silicon solar cell @article{Brendel2016c,
title = {Breakdown of the efficiency gap to 29% based on experimental input data and modelling}, author = {R Brendel and T Dullweber and R Peibst and C Kranz and A Merkle and D Walter}, doi = {10.1002/pip.2696}, year = {2016}, date = {2016-12-01}, journal = {Progress in Photovoltaics: Research and Applications}, volume = {24}, number = {12}, pages = {1475-1486}, abstract = {We demonstrate a procedure for quantifying efficiency gains that treats resistive, recombinative, and optical losses on an equal footing. For this, we apply our conductive boundary model as implemented in the Quokka cell simulator. The generation profile is calculated with a novel analytical light‐trapping model. This model parameterizes the measured reflection spectra and is capable of turning the experimental case gradually into an ideal Lambertian scheme. Simulated and measured short‐circuit current densities agree for our 21.2%‐efficient screen‐printed passivated emitter and rear cell and for our 23.4%‐efficient ion‐implanted laser‐processed interdigitated back‐contacted cell. For the loss analysis of these two cells, we set all experimentally accessible control parameters (e.g., saturation current densities, sheet resistances, and carrier lifetimes) one at a time to ideal values. The efficiency gap to the ultimate limit of 29% is thereby fully explained in terms of both individual improvements and their respective synergistic effects. This approach allows comparing loss structures of different types of solar cells, for example, passivated emitter and rear cell and interdigitated back‐contacted cells.}, keywords = {conductive boundary model, IBC, interdigitated back-contacted cell, loss analysis, passivated emitter and rear cell, PERC, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } We demonstrate a procedure for quantifying efficiency gains that treats resistive, recombinative, and optical losses on an equal footing. For this, we apply our conductive boundary model as implemented in the Quokka cell simulator. The generation profile is calculated with a novel analytical light‐trapping model. This model parameterizes the measured reflection spectra and is capable of turning the experimental case gradually into an ideal Lambertian scheme. Simulated and measured short‐circuit current densities agree for our 21.2%‐efficient screen‐printed passivated emitter and rear cell and for our 23.4%‐efficient ion‐implanted laser‐processed interdigitated back‐contacted cell. For the loss analysis of these two cells, we set all experimentally accessible control parameters (e.g., saturation current densities, sheet resistances, and carrier lifetimes) one at a time to ideal values. The efficiency gap to the ultimate limit of 29% is thereby fully explained in terms of both individual improvements and their respective synergistic effects. This approach allows comparing loss structures of different types of solar cells, for example, passivated emitter and rear cell and interdigitated back‐contacted cells.
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R. Peibst, U. Römer, Y. Larionova, M. Rienäcker, A. Merkle, N. Folchert, S. Reiter, M. Turcu, B. Min, J. Krügener, D. Tetzlaff, E. Bugiel, T. Wietler, and R. Brendel Working principle of carrier selective poly-Si/c-Si junctions: Is tunnelling the whole story? Artikel Solar Energy Materials and Solar Cells 158 , 60-67, (2016). Abstract | Links | BibTeX | Schlagwörter: Modelling, passivating contact, passivation, polysilicon, Silicon solar cell @article{Peibst2016b,
title = {Working principle of carrier selective poly-Si/c-Si junctions: Is tunnelling the whole story?}, author = {R Peibst and U Römer and Y Larionova and M Rienäcker and A Merkle and N Folchert and S Reiter and M Turcu and B Min and J Krügener and D Tetzlaff and E Bugiel and T Wietler and R Brendel}, doi = {10.1016/j.solmat.2016.05.045}, year = {2016}, date = {2016-12-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {158}, pages = {60-67}, abstract = {We present arguments that additional effects besides laterally homogenous tunnelling might occur in carrier-selective poly-Si/c-Si junctions: (i) the symmetrical electrical behaviour of n+ and p+ poly-Si/c-Si junctions, (ii) direct observation of structural modifications of the interfacial oxide upon thermal treatment by transmission electron microscopy, even for poly-Si/c-Si junctions with good passivation quality, and (iii) the achievement of low junction resistances even for interfacial oxide thicknesses >2 nm after thermal treatment. We present an alternative picture, essentially based on a localized current flow through the interfacial oxide, mediated either by local reduction of the oxide layer thickness or by pinholes. In consequence, the local current flow implies transport limitations for both minority and majority carriers in the c-Si absorber, and thus a correlation between recombination current and series resistance. Thus, a poly-Si/c-Si junction can also be explained within the framework of a classical pn junction picture for a passivated, locally contacted emitter, e.g. by the model of Fischer. Both electron selective contacts (n+ poly-Si) and hole selective contacts (p+ poly-Si) can be described consistently when using reasonable input parameters. Especially for p+ poly-Si/c-Si junctions, our model could guideline further improvement.}, keywords = {Modelling, passivating contact, passivation, polysilicon, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } We present arguments that additional effects besides laterally homogenous tunnelling might occur in carrier-selective poly-Si/c-Si junctions: (i) the symmetrical electrical behaviour of n+ and p+ poly-Si/c-Si junctions, (ii) direct observation of structural modifications of the interfacial oxide upon thermal treatment by transmission electron microscopy, even for poly-Si/c-Si junctions with good passivation quality, and (iii) the achievement of low junction resistances even for interfacial oxide thicknesses >2 nm after thermal treatment. We present an alternative picture, essentially based on a localized current flow through the interfacial oxide, mediated either by local reduction of the oxide layer thickness or by pinholes. In consequence, the local current flow implies transport limitations for both minority and majority carriers in the c-Si absorber, and thus a correlation between recombination current and series resistance. Thus, a poly-Si/c-Si junction can also be explained within the framework of a classical pn junction picture for a passivated, locally contacted emitter, e.g. by the model of Fischer. Both electron selective contacts (n+ poly-Si) and hole selective contacts (p+ poly-Si) can be described consistently when using reasonable input parameters. Especially for p+ poly-Si/c-Si junctions, our model could guideline further improvement.
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R. Witteck, D. Hinken, M. R. Vogt, J. Müller, S. Blankemeyer, H. Schulte-Huxel, M. Köntges, K. Bothe, and R. Brendel Optimized interconnection of passivated emitter and rear cells by experimentally verified modeling Artikel IEEE Journal of Photovoltaics 6 (2), 432-439, (2016). Abstract | Links | BibTeX | Schlagwörter: cell interconnection, Conductivity, Optical device fabrication, Optical variables measurement, passivated emitter and rear cells (PERC), Photovoltaic cells, Resistance, Silicon solar cell, solar module, Thyristors, Wires @article{Witteck2016b,
title = {Optimized interconnection of passivated emitter and rear cells by experimentally verified modeling}, author = {R Witteck and D Hinken and M R Vogt and J Müller and S Blankemeyer and H Schulte-Huxel and M Köntges and K Bothe and R Brendel}, doi = {10.1109/JPHOTOV.2016.2514706}, year = {2016}, date = {2016-03-01}, journal = {IEEE Journal of Photovoltaics}, volume = {6}, number = {2}, pages = {432-439}, abstract = {Recent reports about new cell efficiency records are highlighting the continuing development of passivated emitter and rear cells (PERC). Additionally, volume production has started, forming the basis for cutting edge solar modules. However, transferring the high efficiency of the cells into a module requires an adaptation of the conventional front metallization and of the cell interconnection design. This paper studies and compares the module output of various cell interconnection technologies, including conventional cell interconnection ribbons and wires. We fabricate solar cells and characterize their electrical and optical properties. From the cells, we build experimental modules with various cell interconnection technologies. We determine the optical and electrical characteristics of the experimental modules. Based on our experimental results, we develop an analytical model that reproduces the power output of the experimental modules within the measurement uncertainty. The analytical model is then applied to simulate various cell interconnection technologies employing halved cells, optical enhanced cell interconnectors, and multiwires. We also consider the effect of enhancing the cell-to-cell spacing. Based on the experimentally verified simulations, we propose an optimized cell interconnection for a 60-PERC module that achieves a power output of 323 W. Our simulations reveal that wires combined with halved cells show the best module performance. However, applying light-harvesting structures to the cell interconnection ribbons is an attractive alternative for upgrading existing production lines.}, keywords = {cell interconnection, Conductivity, Optical device fabrication, Optical variables measurement, passivated emitter and rear cells (PERC), Photovoltaic cells, Resistance, Silicon solar cell, solar module, Thyristors, Wires}, pubstate = {published}, tppubtype = {article} } Recent reports about new cell efficiency records are highlighting the continuing development of passivated emitter and rear cells (PERC). Additionally, volume production has started, forming the basis for cutting edge solar modules. However, transferring the high efficiency of the cells into a module requires an adaptation of the conventional front metallization and of the cell interconnection design. This paper studies and compares the module output of various cell interconnection technologies, including conventional cell interconnection ribbons and wires. We fabricate solar cells and characterize their electrical and optical properties. From the cells, we build experimental modules with various cell interconnection technologies. We determine the optical and electrical characteristics of the experimental modules. Based on our experimental results, we develop an analytical model that reproduces the power output of the experimental modules within the measurement uncertainty. The analytical model is then applied to simulate various cell interconnection technologies employing halved cells, optical enhanced cell interconnectors, and multiwires. We also consider the effect of enhancing the cell-to-cell spacing. Based on the experimentally verified simulations, we propose an optimized cell interconnection for a 60-PERC module that achieves a power output of 323 W. Our simulations reveal that wires combined with halved cells show the best module performance. However, applying light-harvesting structures to the cell interconnection ribbons is an attractive alternative for upgrading existing production lines.
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2015 |
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H. Mäckel, and P. P. Altermatt IEEE Journal of Photovoltaics 5 (4), 1034-1046, (2015), ISSN: 2156-3381. Links | BibTeX | Schlagwörter: Conductivity, Contact resistance, Electrical resistance measurement, Glass, Lead, silicon, Silicon solar cell, Silver, solar cell metallization, Tunneling @article{Mäckel2015,
title = {Current Transport Through Lead-Borosilicate Interfacial Glass Layers at the Screen-Printed Silver-Silicon Front Contact}, author = {H Mäckel and P P Altermatt}, doi = {10.1109/JPHOTOV.2015.2409561}, issn = {2156-3381}, year = {2015}, date = {2015-07-01}, journal = {IEEE Journal of Photovoltaics}, volume = {5}, number = {4}, pages = {1034-1046}, keywords = {Conductivity, Contact resistance, Electrical resistance measurement, Glass, Lead, silicon, Silicon solar cell, Silver, solar cell metallization, Tunneling}, pubstate = {published}, tppubtype = {article} } |
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H. Hannebauer, S. Schimanke, T. Falcon, P. P. Altermatt, and T. Dullweber Optimized stencil print for low Ag paste consumption and high conversion efficiencies Artikel Energy Procedia 67 , 108-115, (2015), ISSN: 1876-6102, (Proceedings of the Fifth Workshop on Metallization for Crystalline Silicon Solar Cells). Links | BibTeX | Schlagwörter: Dual print, metallization, Paste consumption;, PERC, screen-printing, Silicon solar cell @article{HANNEBAUER2015108,
title = {Optimized stencil print for low Ag paste consumption and high conversion efficiencies}, author = {H Hannebauer and S Schimanke and T Falcon and P P Altermatt and T Dullweber}, doi = {10.1016/j.egypro.2015.03.294}, issn = {1876-6102}, year = {2015}, date = {2015-04-13}, journal = {Energy Procedia}, volume = {67}, pages = {108-115}, note = {Proceedings of the Fifth Workshop on Metallization for Crystalline Silicon Solar Cells}, keywords = {Dual print, metallization, Paste consumption;, PERC, screen-printing, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } |
2014 |
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U. Römer, R. Peibst, B. Lim, J. Krügener, E. Bugiel, T. Wietler, and R. Brendel Solar Energy Materials and Solar Cells 131 , 85-91, (2014), (SiliconPV 2014). Links | BibTeX | Schlagwörter: Passivated Contact, passivation, polysilicon, Silicon solar cell, Tunnel oxide @article{Römer2014b,
title = {Recombination behaviour and contact resistance of n+ and p+ polycrystalline Si/monocrystalline Si junctions*}, author = {U Römer and R Peibst and B Lim and J Krügener and E Bugiel and T Wietler and R Brendel}, doi = {10.1016/j.solmat.2014.06.003}, year = {2014}, date = {2014-12-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {131}, pages = {85-91}, note = {SiliconPV 2014}, keywords = {Passivated Contact, passivation, polysilicon, Silicon solar cell, Tunnel oxide}, pubstate = {published}, tppubtype = {article} } |
2013 |
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M. Lehr, F. Heinemeyer, S. Eidelloth, T. Brendemühl, F. Kiefer, D. Münster, A. Lohse, M. Berger, N. Braun, and R. Brendel How to Obtain Solderable Al/Ni:V/Ag Contacts Artikel Energy Procedia 38 , 375-379, (2013), ISSN: 1876-6102, (Proceedings of the 3rd International Conference on Crystalline Silicon Photovoltaics (SiliconPV 2013)). Links | BibTeX | Schlagwörter: evaporated aluminum, metallization, Silicon solar cell, Solderability @article{LEHR2013375,
title = {How to Obtain Solderable Al/Ni:V/Ag Contacts}, author = {M Lehr and F Heinemeyer and S Eidelloth and T Brendemühl and F Kiefer and D Münster and A Lohse and M Berger and N Braun and R Brendel}, doi = {10.1016/j.egypro.2013.07.292}, issn = {1876-6102}, year = {2013}, date = {2013-09-05}, journal = {Energy Procedia}, volume = {38}, pages = {375-379}, note = {Proceedings of the 3rd International Conference on Crystalline Silicon Photovoltaics (SiliconPV 2013)}, keywords = {evaporated aluminum, metallization, Silicon solar cell, Solderability}, pubstate = {published}, tppubtype = {article} } |
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V. Jung, F. Heinemeyer, M. Köntges, R, and Brendel Ni:Si as Barrier Material for a Solderable PVD Metallization of Silicon Solar Cells Artikel Energy Procedia 38 , 362-367, (2013), ISSN: 1876-6102, (Proceedings of the 3rd International Conference on Crystalline Silicon Photovoltaics (SiliconPV 2013)). Links | BibTeX | Schlagwörter: Long-term stability, PVD-Metallization, Silicon solar cell, Solder connection @article{JUNG2013362,
title = {Ni:Si as Barrier Material for a Solderable PVD Metallization of Silicon Solar Cells}, author = {V Jung and F Heinemeyer and M Köntges and R and Brendel}, doi = {10.1016/j.egypro.2013.07.290}, issn = {1876-6102}, year = {2013}, date = {2013-09-05}, journal = {Energy Procedia}, volume = {38}, pages = {362-367}, note = {Proceedings of the 3rd International Conference on Crystalline Silicon Photovoltaics (SiliconPV 2013)}, keywords = {Long-term stability, PVD-Metallization, Silicon solar cell, Solder connection}, pubstate = {published}, tppubtype = {article} } |
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C. Mader, U. Eitner, S. Kajari-Schröder, and R. Brendel Bow of Silicon Wafers After In-Line High-Rate Evaporation of Aluminum Artikel IEEE Journal of Photovoltaics 3 (1), 212-216, (2013). Links | BibTeX | Schlagwörter: Aluminum, Elastoplastic deformation, In-line evaporation, Photovoltaic cells, Photovoltaic systems, silicon, Silicon solar cell, Strain, Stress, Temperature measurement, wafer bow @article{Mader2013,
title = {Bow of Silicon Wafers After In-Line High-Rate Evaporation of Aluminum}, author = {C Mader and U Eitner and S Kajari-Schröder and R Brendel}, doi = {10.1109/JPHOTOV.2012.2218578}, year = {2013}, date = {2013-01-01}, journal = {IEEE Journal of Photovoltaics}, volume = {3}, number = {1}, pages = {212-216}, keywords = {Aluminum, Elastoplastic deformation, In-line evaporation, Photovoltaic cells, Photovoltaic systems, silicon, Silicon solar cell, Strain, Stress, Temperature measurement, wafer bow}, pubstate = {published}, tppubtype = {article} } |
2012 |
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C. Mader, J. Müller, S. Eidelloth, and R. Brendel Local rear contacts to silicon solar cells by in-line high-rate evaporation of aluminum Artikel Solar Energy Materials and Solar Cells 107 , 272-282, (2012). Links | BibTeX | Schlagwörter: Contact recombination, contact resistivity, In-line evaporation, loss analysis, Rear contact, Silicon solar cell @article{Mader2012,
title = {Local rear contacts to silicon solar cells by in-line high-rate evaporation of aluminum}, author = {C Mader and J Müller and S Eidelloth and R Brendel}, doi = {10.1016/j.solmat.2012.06.047}, year = {2012}, date = {2012-12-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {107}, pages = {272-282}, keywords = {Contact recombination, contact resistivity, In-line evaporation, loss analysis, Rear contact, Silicon solar cell}, pubstate = {published}, tppubtype = {article} } |
2011 |
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C. Mader, M. Kessler, U. Eitner, and R. Brendel Temperature of silicon wafers during in-line high-rate evaporation of aluminum Artikel Solar Energy Materials and Solar Cells 95 (11), 3047-3053, (2011), ISSN: 0927-0248. Links | BibTeX | Schlagwörter: In-line evaporation, modeling, Process optimization, Silicon solar cell, Temperature @article{Mader2011c,
title = {Temperature of silicon wafers during in-line high-rate evaporation of aluminum}, author = {C Mader and M Kessler and U Eitner and R Brendel}, doi = {10.1016/j.solmat.2011.06.031}, issn = {0927-0248}, year = {2011}, date = {2011-11-01}, journal = {Solar Energy Materials and Solar Cells}, volume = {95}, number = {11}, pages = {3047-3053}, keywords = {In-line evaporation, modeling, Process optimization, Silicon solar cell, Temperature}, pubstate = {published}, tppubtype = {article} } |