he potential of 3-D printing polymers to achieve low-weight space flight hardware has seen increa... more he potential of 3-D printing polymers to achieve low-weight space flight hardware has seen increasing interest. Additionally, robust 3-D printed polymer vacuum equipment would provide highly attractive low-cost alternatives to conventional industrial-scale tools for the scientific community. Inorganic barrier coatings of plastic parts can be used to minimize outgassing and damage to polymers from extreme vacuum environments. Among different coating technologies in this area of research, atomic layer deposition (ALD) has shown the most promise. Nevertheless, the exact formation morphology of ALD coatings on 3-D printed polymers under vacuum are not yet well understood, which hinders use of 3-D printed polymers in vacuum environments. In this study, the film formation mechanisms of ALD alumina on porous 3-D printed polymers are investigated via SEM, EDS, XRD, ATR-FTIR, and XPS. ALD alumina is deposited on 3-D printed pigmented and un-pigmented acrylonitrile butadiene styrene, polycarbonate, commercially available polypropylene, and pure polypropylene. The results reveal that the formation of the ALD barrier layer, its thickness, and diffusion of ALD precursor materials into the polymer substrate is a multi-scale phenomenon, and that substrate porosity and polymer functionality both dominate film formation behavior. Additionally, this study demonstrates that during ALD processes on 3-D printed polymers a vapor phase infiltration (VPI) growth mode also occurs, especially where porosity is present.
Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual p... more Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Pasanen, Toni; Vähänissi, Ville; Wolny, Franziska; Oehlke, Alexander; Wagner, Matthias; Juntunen, Mikko A.; Heikkinen, Ismo T. S.; Salmi, Emma; Sneck, Sami; Vahlman, Henri; Tolvanen, Antti; Hyvärinen, Jaakko; Savin, Hele Industrial Applicability of Antireflection-Coating-Free Black Silicon on PERC Solar Cells and Modules
Abstract Open-source scientific hardware based on affordable fused filament fabrication (FFF) 3-D... more Abstract Open-source scientific hardware based on affordable fused filament fabrication (FFF) 3-D printing has the potential to reduce the cost of research tools considerably. So far, development has focused on tools that do not require compatibility with vacuum environments. Highly porous 3-D printed plastics require surface treatments to mitigate their outgassing, and in this study we explored the outgassing reduction from 3-D printed black-colored acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) using a commercial vacuum sealing resin as well as atomic layer deposited (ALD) aluminum oxide (AlOx). The outgassing properties of uncoated plastics could not be measured due to a too high level of outgassing, which was attributed to their high porosity and high specific surface area. However, both the commercial resin and the ALD coatings reduced the extent of outgassing from both ABS and PC, which enabled their comparison by residual gas analysis (RGA). Remarkably, the outgassing performance achieved with ALD AlOx was superior to the performance of the commercial vacuum resin across a temperature range of 40 to 100 °C for both plastics, despite the uneven coverage of the plastic surface with AlOx. Results indicated that both ABS and PC could be made compatible with at least moderate vacuums using ALD AlOx. Thus, the fabrication of laboratory vacuum tools can be realized with affordable 3-D printed plastics. However, further studies on the physical mechanisms behind the outgassing reduction and the durability of the coatings are required.
ABSTRACT: Azobenzene chromophores are an ideal choice for material applications where functionali... more ABSTRACT: Azobenzene chromophores are an ideal choice for material applications where functionality needs to be activated in a precise remote-controlled fashion. The azobenzene stimuli-response falls into two categories, either based on efficient trans-to-cis photoisomerization and a high cis yield enabling on−off type functions, or relying on a fast trans−cis−trans cycling creating motion in the material system. Herein, we show that using bisazochromophores instead of the more common monoazobenzene derivatives makes a differ-ence in the performance of light-responsive azopolymers, more specifically in photo-orientation and all-optical surface patterning. Our findings point out that polymer-bisazobenzene complexes are an attractive alternative as high-performance photoreponsive materials and that although their properties are highly sensitive to the extent of conjugation in the system, they can be designed into relatively transparent films with high performance for all-optical patte...
Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual p... more Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Heikkinen, Ismo T.S.; Kauppinen, Christoffer; Liu, Zhengjun; Asikainen, Sanja M.; Spoljaric, Steven; Seppälä, Jukka V.; Savin, Hele; Pearce, Joshua M. Chemical compatibility of fused filament fabrication-based 3-D printed components with solutions commonly used in semiconductor wet processing
Many defects can cause significant bulk degradation in crystalline silicon, which inherently limi... more Many defects can cause significant bulk degradation in crystalline silicon, which inherently limits solar cell efficiency. Perhaps the most well-known source of light-induced bulk degradation (LID) in Czochralski-grown silicon is the boron-oxygen defect. However, metal impurities, such as copper, can also cause severe degradation. Advanced hydrogenation processes incorporating minority carrier injection can effectively passivate boron-oxygen complexes, but their effect on copper-induced degradation has not been studied previously. Herein, we explore the effect of hydrogenation on LID in copper-contaminated silicon. Without hydrogenation the bulk lifetime decreases down to $5\ \mu\mathrm{s}$ while in hydrogenated samples the bulk lifetime remains above $300\ \mu\mathrm{s}$ during the whole degradation cycle. The results thus indicate that even in heavily copper-contaminated silicon hydrogenation can passivate Cu precipitates and mitigate Cu-LID.
he potential of 3-D printing polymers to achieve low-weight space flight hardware has seen increa... more he potential of 3-D printing polymers to achieve low-weight space flight hardware has seen increasing interest. Additionally, robust 3-D printed polymer vacuum equipment would provide highly attractive low-cost alternatives to conventional industrial-scale tools for the scientific community. Inorganic barrier coatings of plastic parts can be used to minimize outgassing and damage to polymers from extreme vacuum environments. Among different coating technologies in this area of research, atomic layer deposition (ALD) has shown the most promise. Nevertheless, the exact formation morphology of ALD coatings on 3-D printed polymers under vacuum are not yet well understood, which hinders use of 3-D printed polymers in vacuum environments. In this study, the film formation mechanisms of ALD alumina on porous 3-D printed polymers are investigated via SEM, EDS, XRD, ATR-FTIR, and XPS. ALD alumina is deposited on 3-D printed pigmented and un-pigmented acrylonitrile butadiene styrene, polycarbonate, commercially available polypropylene, and pure polypropylene. The results reveal that the formation of the ALD barrier layer, its thickness, and diffusion of ALD precursor materials into the polymer substrate is a multi-scale phenomenon, and that substrate porosity and polymer functionality both dominate film formation behavior. Additionally, this study demonstrates that during ALD processes on 3-D printed polymers a vapor phase infiltration (VPI) growth mode also occurs, especially where porosity is present.
Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual p... more Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Pasanen, Toni; Vähänissi, Ville; Wolny, Franziska; Oehlke, Alexander; Wagner, Matthias; Juntunen, Mikko A.; Heikkinen, Ismo T. S.; Salmi, Emma; Sneck, Sami; Vahlman, Henri; Tolvanen, Antti; Hyvärinen, Jaakko; Savin, Hele Industrial Applicability of Antireflection-Coating-Free Black Silicon on PERC Solar Cells and Modules
Abstract Open-source scientific hardware based on affordable fused filament fabrication (FFF) 3-D... more Abstract Open-source scientific hardware based on affordable fused filament fabrication (FFF) 3-D printing has the potential to reduce the cost of research tools considerably. So far, development has focused on tools that do not require compatibility with vacuum environments. Highly porous 3-D printed plastics require surface treatments to mitigate their outgassing, and in this study we explored the outgassing reduction from 3-D printed black-colored acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) using a commercial vacuum sealing resin as well as atomic layer deposited (ALD) aluminum oxide (AlOx). The outgassing properties of uncoated plastics could not be measured due to a too high level of outgassing, which was attributed to their high porosity and high specific surface area. However, both the commercial resin and the ALD coatings reduced the extent of outgassing from both ABS and PC, which enabled their comparison by residual gas analysis (RGA). Remarkably, the outgassing performance achieved with ALD AlOx was superior to the performance of the commercial vacuum resin across a temperature range of 40 to 100 °C for both plastics, despite the uneven coverage of the plastic surface with AlOx. Results indicated that both ABS and PC could be made compatible with at least moderate vacuums using ALD AlOx. Thus, the fabrication of laboratory vacuum tools can be realized with affordable 3-D printed plastics. However, further studies on the physical mechanisms behind the outgassing reduction and the durability of the coatings are required.
ABSTRACT: Azobenzene chromophores are an ideal choice for material applications where functionali... more ABSTRACT: Azobenzene chromophores are an ideal choice for material applications where functionality needs to be activated in a precise remote-controlled fashion. The azobenzene stimuli-response falls into two categories, either based on efficient trans-to-cis photoisomerization and a high cis yield enabling on−off type functions, or relying on a fast trans−cis−trans cycling creating motion in the material system. Herein, we show that using bisazochromophores instead of the more common monoazobenzene derivatives makes a differ-ence in the performance of light-responsive azopolymers, more specifically in photo-orientation and all-optical surface patterning. Our findings point out that polymer-bisazobenzene complexes are an attractive alternative as high-performance photoreponsive materials and that although their properties are highly sensitive to the extent of conjugation in the system, they can be designed into relatively transparent films with high performance for all-optical patte...
Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual p... more Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Heikkinen, Ismo T.S.; Kauppinen, Christoffer; Liu, Zhengjun; Asikainen, Sanja M.; Spoljaric, Steven; Seppälä, Jukka V.; Savin, Hele; Pearce, Joshua M. Chemical compatibility of fused filament fabrication-based 3-D printed components with solutions commonly used in semiconductor wet processing
Many defects can cause significant bulk degradation in crystalline silicon, which inherently limi... more Many defects can cause significant bulk degradation in crystalline silicon, which inherently limits solar cell efficiency. Perhaps the most well-known source of light-induced bulk degradation (LID) in Czochralski-grown silicon is the boron-oxygen defect. However, metal impurities, such as copper, can also cause severe degradation. Advanced hydrogenation processes incorporating minority carrier injection can effectively passivate boron-oxygen complexes, but their effect on copper-induced degradation has not been studied previously. Herein, we explore the effect of hydrogenation on LID in copper-contaminated silicon. Without hydrogenation the bulk lifetime decreases down to $5\ \mu\mathrm{s}$ while in hydrogenated samples the bulk lifetime remains above $300\ \mu\mathrm{s}$ during the whole degradation cycle. The results thus indicate that even in heavily copper-contaminated silicon hydrogenation can passivate Cu precipitates and mitigate Cu-LID.
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Papers by Ismo T S Rauha