1.
P Bayerl; N Folchert; J Bayer; M Dzinnik; C Hollemann; R Brendel; R Peibst; R J Haug
In: Progress in Photovoltaics: Research and Applications, Bd. 29, Nr. 8, S. 936-942, 2021.
@article{Bayerl2021,
title = {Contacting a single nanometer-sized pinhole in the interfacial oxide of a poly-silicon on oxide (POLO) solar cell junction},
author = {P Bayerl and N Folchert and J Bayer and M Dzinnik and C Hollemann and R Brendel and R Peibst and R J Haug},
doi = {10.1002/pip.3417},
year = {2021},
date = {2021-08-01},
journal = {Progress in Photovoltaics: Research and Applications},
volume = {29},
number = {8},
pages = {936-942},
abstract = {The electrical current through poly-Si on oxide (POLO) solar cells is mediated by tunneling and by nanometer-sized pinholes in the interfacial oxide. To distinguish the two processes, a POLO junction with a measured pinhole density of 1 × 107 cm−2 is contacted by different contact areas ranging from 1 μm2 to 2.5 × 105 μm2, and the temperature-dependent current–voltage curves are measured for the different devices. Model regressions to the measured curves, their temperature dependence, and the quantized value of contact resistances indicate average numbers of pinholes per device corresponding to the expected pinhole density. For the small contacts, the different transport processes can be studied separately, which facilitates further improvements in respect to the present-day POLO junctions. Single-pinhole transport is found for one of the contacts with an area of 1 μm2. Random telegraph noise observed for this device in the current–voltage characteristics shows a high sensitivity to single charges.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The electrical current through poly-Si on oxide (POLO) solar cells is mediated by tunneling and by nanometer-sized pinholes in the interfacial oxide. To distinguish the two processes, a POLO junction with a measured pinhole density of 1 × 107 cm−2 is contacted by different contact areas ranging from 1 μm2 to 2.5 × 105 μm2, and the temperature-dependent current–voltage curves are measured for the different devices. Model regressions to the measured curves, their temperature dependence, and the quantized value of contact resistances indicate average numbers of pinholes per device corresponding to the expected pinhole density. For the small contacts, the different transport processes can be studied separately, which facilitates further improvements in respect to the present-day POLO junctions. Single-pinhole transport is found for one of the contacts with an area of 1 μm2. Random telegraph noise observed for this device in the current–voltage characteristics shows a high sensitivity to single charges.
2.
M Müller; B Wolpensinger; B Min; G Fischer; P Palinginis; D H Neuhaus
In: IEEE Journal of Photovoltaics, Bd. 10, Nr. 6, S. 1642-1647, 2020.
@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 = {},
pubstate = {published},
tppubtype = {article}
}
3.
F Haase; J Käsewieter; S R Nabavi; E Jansen; R Rolfes; M Köntges
In: IEEE Journal of Photovoltaics, Bd. 8, Nr. 6, S. 1510-1524, 2018, ISSN: 2156-3381.
@article{Haase2018cb,
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 = {},
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.
4.
H Schulte-Huxel; D J Friedman; A C Tamboli
String-Level Modeling of Two, Three, and Four Terminal Si-Based Tandem Modules Artikel
In: IEEE Journal of Photovoltaics, Bd. 8, Nr. 5, S. 1370-1375, 2018.
@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 = {},
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.
5.
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; R Brendel
In: IEEE Journal of Photovoltaics, Bd. 8, Nr. 3, S. 719-725, 2018, ISSN: 2156-3381.
@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},
keywords = {},
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
6.
J Krügener; F Haase; M Rienäcker; R Brendel; H J Osten; R Peibst
In: Solar Energy Materials and Solar Cells, Bd. 173, S. 85-91, 2017, ISSN: 0927-0248, (Proceedings of the 7th international conference on Crystalline Silicon Photovoltaics).
@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 = {},
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%.
7.
V Titova; B Veith-Wolf; D Startsev; J Schmidt
In: Energy Procedia, Bd. 124, Nr. Supplement C, S. 441 - 447, 2017, ISSN: 1876-6102, (7th International Conference on Silicon Photovoltaics, SiliconPV 2017, 3-5 April 2017, Freiburg, Germany).
@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 = {},
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%.
8.
Y Larionova; M Turcu; S Reiter; R Brendel; D Tetzlaff; J Krügener; T Wietler; U Höhne; J-D Kähler; R Peibst
In: physica status solidi (a), Bd. 214, Nr. 8, S. 1700058, 2017, ISSN: 1862-6319, (1700058).
@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 = {},
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.
9.
H Schulte-Huxel; R Witteck; H Holst; M R Vogt; S Blankemeyer; D Hinken; T Brendemühl; T Dullweber; K Bothe; M Köntges; R Brendel
In: IEEE Journal of Photovoltaics, Bd. 7, Nr. 1, S. 25-31, 2017, ISSN: 2156-3381.
@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 = {},
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.
10.
R Brendel; T Dullweber; R Peibst; C Kranz; A Merkle; D Walter
Breakdown of the efficiency gap to 29% based on experimental input data and modelling Artikel
In: Progress in Photovoltaics: Research and Applications, Bd. 24, Nr. 12, S. 1475-1486, 2016.
@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 = {},
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.
11.
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; R Brendel
Working principle of carrier selective poly-Si/c-Si junctions: Is tunnelling the whole story? Artikel
In: Solar Energy Materials and Solar Cells, Bd. 158, S. 60-67, 2016.
@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 = {},
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.
12.
R Witteck; D Hinken; M R Vogt; J Müller; S Blankemeyer; H Schulte-Huxel; M Köntges; K Bothe; R Brendel
Optimized interconnection of passivated emitter and rear cells by experimentally verified modeling Artikel
In: IEEE Journal of Photovoltaics, Bd. 6, Nr. 2, S. 432-439, 2016.
@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 = {},
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.
13.
H Mäckel; P P Altermatt
In: IEEE Journal of Photovoltaics, Bd. 5, Nr. 4, S. 1034-1046, 2015, ISSN: 2156-3381.
@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 = {},
pubstate = {published},
tppubtype = {article}
}
14.
H Hannebauer; S Schimanke; T Falcon; P P Altermatt; T Dullweber
Optimized stencil print for low Ag paste consumption and high conversion efficiencies Artikel
In: Energy Procedia, Bd. 67, S. 108-115, 2015, ISSN: 1876-6102, (Proceedings of the Fifth Workshop on Metallization for Crystalline Silicon Solar Cells).
@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 = {},
pubstate = {published},
tppubtype = {article}
}
15.
U Römer; R Peibst; B Lim; J Krügener; E Bugiel; T Wietler; R Brendel
In: Solar Energy Materials and Solar Cells, Bd. 131, S. 85-91, 2014, (SiliconPV 2014).
@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 = {},
pubstate = {published},
tppubtype = {article}
}
16.
V Jung; F Heinemeyer; M Köntges; R; Brendel
Ni:Si as Barrier Material for a Solderable PVD Metallization of Silicon Solar Cells Artikel
In: Energy Procedia, Bd. 38, S. 362-367, 2013, ISSN: 1876-6102, (Proceedings of the 3rd International Conference on Crystalline Silicon Photovoltaics (SiliconPV 2013)).
@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 = {},
pubstate = {published},
tppubtype = {article}
}
17.
M Lehr; F Heinemeyer; S Eidelloth; T Brendemühl; F Kiefer; D Münster; A Lohse; M Berger; N Braun; R Brendel
How to Obtain Solderable Al/Ni:V/Ag Contacts Artikel
In: Energy Procedia, Bd. 38, S. 375-379, 2013, ISSN: 1876-6102, (Proceedings of the 3rd International Conference on Crystalline Silicon Photovoltaics (SiliconPV 2013)).
@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 = {},
pubstate = {published},
tppubtype = {article}
}
18.
C Mader; U Eitner; S Kajari-Schröder; R Brendel
Bow of Silicon Wafers After In-Line High-Rate Evaporation of Aluminum Artikel
In: IEEE Journal of Photovoltaics, Bd. 3, Nr. 1, S. 212-216, 2013.
@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 = {},
pubstate = {published},
tppubtype = {article}
}
19.
C Mader; J Müller; S Eidelloth; R Brendel
Local rear contacts to silicon solar cells by in-line high-rate evaporation of aluminum Artikel
In: Solar Energy Materials and Solar Cells, Bd. 107, S. 272-282, 2012.
@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 = {},
pubstate = {published},
tppubtype = {article}
}
20.
C Mader; M Kessler; U Eitner; R Brendel
Temperature of silicon wafers during in-line high-rate evaporation of aluminum Artikel
In: Solar Energy Materials and Solar Cells, Bd. 95, Nr. 11, S. 3047-3053, 2011, ISSN: 0927-0248.
@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 = {},
pubstate = {published},
tppubtype = {article}
}