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  1. >24% screen printed Cu contacted n-TOPCon solar cells with successful implementation of LECO process

    Ok, Young-Woo ; Zhong, Ruohan ; Upadhyaya, Vijaykumar ; ... - Solar Energy Materials and Solar Cells
    In this paper, we report the successful fabrication of >24.0 % efficiency n-TOPCon Si solar cells with screen-printed, fire-through Cu contact to n-TOPCon on the rear side and Ag contacted boron emitter on the front side by implementing optimized firing and LECO conditions. The highest efficiency (24.3%) Cu contacted n-TOPCon cell in this study showed excellent cell performance parameters with Voc >730 mV, Jsc of 41.1 mA/cm2 and FF of 80.8%, resulting in an absolute efficiency gap of 0.2% between Cu-contacted and fully Ag contacted n-TOPCon cells (24.5%). The mini-module fabricated with the Cu contacted n-TOPCon cell showed excellent reliabilitymore » and durability of open-circuit voltage (Voc), pseudo fill factor (pFF) and efficiency after prolonged damp-heat tests. Such high efficiency screen printed Cu contacted n-TOPCon cells provide unique opportunity to replace very expensive Ag contact on n-TOPCon with cheaper screen printable Cu metal pastes.« less

  2. Unveiling the Role of In Situ Al2O3 Passivation in Molecular-Ink-Processed CuIn(S,Se)2 Photovoltaics

    Septina, Wilman ; Paranhos Lopes, Jade ; Muzzillo, Christopher P. ; ... - ACS Applied Energy Materials
    Here, we report on the optimization of in situ passivation of ink-based CuIn(S,Se)2 thin-film solar cells via controlled incorporation of Al2O3 in CuIn(S,Se)2 films by the addition of Al(NO3)3 to the molecular ink precursor. For this purpose, the Al/(Al + In) (AAI) metal ratio was varied from 0.05 to 0.30. We observe that the efficiency of the cells made of Al2O3-incorporated CuIn(S,Se)2 is consistently higher than those without Al2O3, especially due to an improvement in open-circuit voltage (VOC) and fill factor (FF), for all tested AAI ratios. With an AAI of 0.05, a maximum efficiency of 11.2% and an averagemore » efficiency of 8.5% (measured across 18 cells) was achieved, compared to 8.5% maximum efficiency and 6.5% average efficiency for Al-free CuIn(S,Se)2. Furthermore, we find that cells made of Al2O3-incorporated CuIn(S,Se)2 with an AAI of 0.2 show a narrow distribution in the photovoltaic performance, indicating higher reproducibility and higher FF. Energy-dispersive X-ray spectroscopy shows that, at AAI = 0.2, Al2O3 is distributed more homogeneously at the surface of the Al2O3-incorporated CISSe. Capacitance-voltage measurements reveal a reduced defect density by incorporation of Al2O3, which could be partly responsible for the higher VOC. Furthermore, using detailed surface analysis with various X-ray and electron spectroscopy methods, we derive chemical and electronic structure information from the surface. With ultraviolet photoelectron (UPS) and inverse photoemission spectroscopies (IPES), the electronic band gap of the CuIn(S,Se)2 thin-film surface is found to increase from 1.22 to 1.88 eV (+-0.12 eV) with Al2O3 incorporation. This is accompanied by a clear reduction of the conduction band spike at the CdS/CISSe interface due to Al2O3 addition, as derived by both UPS and IPES as well as temperature-dependent VOC measurements.« less

  3. Support of Adhesion Mechanisms in Al2O3 Aerosol Deposition Through Laser-Induced Particle Impact Testing

    Murray, Shannon Elizabeth ; Sarracino, Alex ; McPherson, Shane L. ; ... - Journal of Thermal Spray Technology
    Aerosol deposition (AD) is a kinetic spray process capable of depositing ceramic coatings at room temperature, but AD process development is generally a laborious exploration of a large process parameter space. Here, this paper presents a case study investigating whether laser-induced particle impact testing (LIPIT) could be applied to expedite development of an alumina (Al2O3) coating on nickel (Ni): Specifically, whether LIPIT measurements could predict critical velocities of adhesion on Ni and Al2O3, and the effect of ball milling the Al2O3 powder. Because LIPIT has a diffraction-limited lower bound on imageable particle size, the usefulness of Al2O3 powder agglomerates asmore » a proxy for single particles was additionally studied. Overall, LIPIT measurements and AD sprays agreed that ball milling dramatically improves adhesion. Additionally, LIPIT measurements of critical velocity of adhesion of Al2O3 powder agglomerates on Ni and Al2O3 substrates (150 meters per second [m/s] and 250 m/s, respectively) quantitatively agreed with predictions from a previously published model based on picoindentation and molecular dynamics simulations. Together, these findings support the established hypothesis that Al2O3 adheres via a dislocation-mediated mechanism in AD, that Al2O3 powder agglomerates adhere as individual constituent particles rather than collectively, and that, for this case study, LIPIT measurements were predictive of AD process parameters.« less

  4. Impacts of Focused Ion Beam Processing on the Fabrication of Nanoscale Functionalized Probes

    Wang, Xiang ; Taylor, Sandra D. ; Sassi, Michel J. ; ... - Inorganic Chemistry
    Herein, we examine the impact of Ga+ ion kinetic energy and the target material type on the extent of ion implantation and structural damage in atomic force microscopy probes made of Al2O3 and ZnO manufactured by focused ion beam (FIB) using scanning transmission electron microscopy and energy-dispersive X-ray mapping. Penetration of Ga into the Al2O3 lattice induced structural distortions and amorphization. For ZnO probes, Ga is uniformly dispersed across the surface, resulting in the formation of distinct clusters. Atom probe tomography further validates the Ga distributions in Al2O3 and ZnO nanoprobes. Complementary Monte Carlo simulations with the transport of ionsmore » in the matter program indicated that the introduction of Ga+ prompts the generation of cation and anion vacancies, an occurrence more pronounced in Al2O3 compared to ZnO. In conclusion, this study not only enriches the knowledge of ion-matter interactions, but also serves as a practical guide for the fabrication of nanoscale functionalized AFM probes.« less

  5. Nonpyrophoric alternative to trimethylaluminum for the atomic layer deposition of Al2O3

    Swarup, Jay V. ; Chuang, Heng-Ray ; Jensen, James T. ; ... - Journal of Vacuum Science and Technology A
    We have examined the atomic layer deposition (ALD) of Al2O3 using a nonpyrophoric precursor, which possesses only Al–N bonds and no Al–C bonds: Al(N(CH3)2)2(–N(C2H5)–C2H4–N(C2H5)2), which we refer to as bis-dimethylamino-diamino-aluminum (BDMADA-Al). We employed a quartz crystal microbalance (QCM) to monitor ALD in situ and in real time, and the deposited thin films have been characterized using x-ray photoelectron spectroscopy, spectroscopic ellipsometry, x-ray reflectivity, and atomic force microscopy. Films deposited with BDMADA-Al result in near-stoichiometric Al2O3 at temperatures ranging from T = 120 to 285 °C using H2O as the coreactant and at T = 285 °C using t-BuOH as themore » coreactant. The properties of the films (density, C incorporation, stoichiometry, growth rates) are comparable using either BDMADA-Al or trimethylaluminum (TMA) as the precursor under similar reaction conditions. The N content in the films deposited with BDMADA-Al as the precursor is <1% at both T = 120 and 285 °C. Additionally, both BDMADA-Al|t-BuOH and TMA|t-BuOH processes deposit near-stoichiometric Al2O3 at T = 285 °C, while neither process chemistry produces a constant growth rate per cycle at T = 120 °C. Close examination of single cycle QCM data from BDMADA-Al ALD indicates unique ligand exchange reaction mechanisms during each of the half-reactions. Experimentally, we have evidence supporting the mechanism in which upon the chemisorption of BDMADA-Al, the species on the surface retains the –N(CH3)2 ligands, while the diamine ligand is mostly lost on dissociative adsorption, except possibly at the higher temperature (285 °C). As a result, our work demonstrates that BDMADA-Al can be used as an effective alternative precursor to TMA for the ALD of Al2O3.« less

  6. Carboxyl-functionalized perovskite enables ALD growth of a compact and uniform ion migration barrier

    Choi, Deokjae ; Shin, Donghoon ; Li, Chongwen ; ... - Joule
    Mixed-halide wide-band-gap perovskites are critical components of highly efficient tandem cells, but their operating stability is limited by halide migration. Metal oxides deposited via atomic layer deposition (ALD) have been shown to block halide migration; however, previously pursued methods result in inhomogeneous nucleation and growth. We hypothesized that functionalizing the perovskite surface with ALD-active carboxyl groups could promote nucleation and enable higher-temperature metal oxide growth. We find that 5-ammonium valeric acid iodide (5-AVAI) facilitates the formation of a compact and uniform aluminum oxide (Al2O3) layer and allows growth at 100°C compared with the previous limit of 75°C. We demonstrate thatmore » halide migration into the C60 electron transport layer is reduced by a factor of 10 compared with the reference case. Finally, Al2O3-capped perovskite solar cells with a band gap of 1.78 eV retain 90% of their initial power conversion efficiency after 1,000 h of continuous operation under 1-sun illumination at 55°C.« less

  7. Revealing the corrosion mechanism of an Al0.1CoCrFeNi high entropy alloy in high temperature carbon dioxide environment

    Zhou, Shanliang ; Liang, Zihang ; Huang, Xi ; ... - Corrosion Science
    The corrosion behavior of an Al0.1CoCrFeNi HEA in high temperature CO2 at 850 °C for different exposure periods was investigated using different characterization methods. Further, weight gain increased with extended exposure periods, yet it remained lower than most conventional alloys. A double-layer oxide film consisting of Cr2O3 and Al2O3 formed after 100 and 500 h of exposure, while a single layer of Cr2O3 developed after 1000 h of exposure. CoCrFeNi particles with an FCC structure were embedded in the oxide films irrespective of the exposure periods. Moreover, a transition zone containing numerous striped-like Al2O3 oxides along the grain boundaries wasmore » developed underneath the oxide films.« less

  8. Prediction of the Cu Oxidation State from EELS and XAS Spectra Using Supervised Machine Learning

    Gleason, Samuel P. ; Carbone, Matthew R. ; Lu, Deyu ; ... - Microscopy and Microanalysis
    Electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) provide detailed information about distributions and locations of atoms, their coordination numbers and oxidation states, and the bonding characteristics [1]. However, analysis of XAS/EELS data often relies on matching the spectra of an unknown experimental sample to a series of simulated or experimental spectra of standard samples. Here, this limits analysis throughput and the ability to extract quantitative information from a sample.

  9. Butene-Rich Alkene Formation from 2,3-Butanediol through Dioxolane Intermediates

    Cordon, Michael J. ; Li, Meijun ; Yang, Xiaokun ; ... - ACS Sustainable Chemistry & Engineering
    The cost-effective production of sustainable aviation fuels (SAF) remains a major challenge within the energy sector. One approach to address this is the fermentation of biomass feedstocks into oxygenates followed by catalytic conversion to alkenes or other oligomerization precursors. 2,3-Butanediol (BDO) is a promising fermentation product due to its four-carbon nature, its decreased microorganism toxicity and associated higher maximum fermentation titers relative to other alcohols and oxygenates, and its capacity to be readily converted into butene isomers and longer chain alkenes. BDO conversion is currently constrained by separation challenges for BDO isolation due to its high boiling point and hydrophilicity.more » Here, this work expands upon previous BDO reactive separation via dioxolane formation over a solid acid catalyst by investigating the conversion of dioxolanes into alkene mixtures. Dioxolanes were formed from a range of aldehydes and subsequently converted over a Cu/ZSM-5 catalyst (448–523 K) via an ether cleavage, hydrogenation, and dehydration reaction network to form alkene-rich product mixtures (96% C3+ alkene yield, 523 K). This selectivity is greater than that of direct BDO conversion to alkenes over an identical catalyst (89%, 523 K). C3+ alkene selectivity is maximized between 498 and 523 K at complete dioxolane conversion without significant alkene hydrogenation to alkanes. The alkene product distributions can be tailored via both aldehyde selection during dioxolane formation and the dioxolane conversion reaction temperature. Alkene mixtures from dioxolane conversion predominantly reflect the carbon chain length and stereochemistry of BDO and the initial aldehyde at or below 498 K, yet higher reaction temperatures yield alkene mixtures of similar carbon chain distributions, regardless of initial aldehyde selection. Deactivation of the Cu/ZSM-5 catalyst is observed for multiple steps of the overall reaction network but can be minimized by facilitating the complete dioxolane-to-alkene reaction network at temperatures of at least 498 K.« less

  10. Beneficial effect of copper on pitting resistance of Ni-Cr-Fe alloys

    Hariharan, Karthikeyan ; Li, Sirui ; Taylor, Christopher D. ; ... - Electrochimica Acta
    This study examines the effect of copper alloying on pitting resistance in a model solid solution FCC Ni-13%Cr-10%Fe alloy through potentiodynamic and potentiostatic polarization in 0.1 M NaCl in conjunction with an analysis using first-principles competitive electro-chemisorption modeling. The pitting potential increased with increasing Cu content in the alloy. Furthermore, the extent of metastable pit growth was suppressed and the incubation time for metastable to stable pit transition increased with Cu content. The first-principles competitive adsorption calculations suggested that Cu alloying suppresses chloride ion adsorption on the alloy surface in a simulated pit environment, which inhibits active dissolution at themore » pit bottom, enhances proton adsorption, and thereby increases the local pH at the pit bottom. In conclusion, we propose that these two effects of Cu in solid solution combine to reduce pit stability and may act in addition to the enrichment of Cu on the corroding pit surface.« less
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