SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
An approach to slow down the polymer solar cell ink aging by employing an additive (i.e., PCBM variants) was developed. It is inferred that PCBMs in the ink act as a co-solvent and slow down the polymer pre-aggregation.
ITRPV silver consumption of standard low-temperature and high-temperature paste as compared to reactive silver ink. As little as 16.4 mg of silver is consumed when a busbarless cell is metallized with reactive silver ink.
Abstract This paper presents a versatile nanotransfer printing method for achieving large-area sub-micron patterns of functional materials. Organosilicate ink formulations combined with effective release layers have been shown to facilitate patterning of materials through the commonly used patterning approaches—lift off, physical etching and chemical etching. In this paper, we demonstrate that organosilicate ink formulations function as an effective resist owing to its superior physico-chemical stability whereas the release layers ensure clean removal of the resist post patterning. We successfully demonstrate patterning of sub-micron structures (800 nm feature sizes) of chromium metal through the lift off approach, silicon through reactive ion etching technique and silicon dioxide through wet chemical etching technique illustrating the versatility of the reported method. This patterning methodology represents a significant advancement in enabling nanostructure fabrication within resource-constrained laboratories. The approach requires nothing more than a master mold containing the desired structures, a spin coater, a low-temperature hotplate, and a desktop reactive ion etch tool.
The mid-wave infrared (MWIR), ranging from 2 to 5 micrometers, is of substantial interest for chemical sensing, imaging, and spectroscopy. Black phosphorus (bP)–based MWIR light emitters and detectors have been shown to outperform the state-of-the-art for commercial devices due to the low Auger recombination coefficient of bP. However, the scalability of these devices remains a challenge. Here, we report a bP ink formula that preserves the exceptional MWIR optoelectronic properties of bP to deposit centimeter-scale, uniform, and pinhole free films with a photoluminescence quantum yield higher than competing III-V and II-VI semiconductors with similar bandgaps at high excitation regime. As a proof of concept, we use bP ink as a “phosphor” on a red commercial light-emitting diode to demonstrate bright MWIR light emission. We also show that these films can be integrated into heterostructure device architectures with electron and hole selective contacts for direct-injected light emission and detection in MWIR.
Platinum group metal (PGM) catalysts are the major electrocatalysts for oxygen reduction reaction (ORR) in the polymer electrolyte membrane fuel cells (PEMFCs). The cost becomes unaffordable if the PEMFC is in massive application. The PGM-Free catalyst shows very promising activity in rotation disk electrode (RDE) testing. The half-wave potential could reach 0.91 V versus standard hydrogen electrode (SHE). However, in a membrane electrode assembly (MEA), the performance of PGM-Free catalysts is not good enough to replace the PGM catalysts. Since the PGM-free catalysts are so different from the PGM catalysts in terms of catalytic activity, stability, surface conditions, particle size, etc., the fabrication of PGM-Free catalyst MEA cannot simply copy the method of making PGM MEA. Here we proposed a novel method of fabricating PGM-Free catalyst MEA, so that the intrinsic catalyst activity from RDE can be translated into MEA performance. The method is based on the catalyst coated membrane (CCM) method using optimized ionomer to carbon (I/C) ratio and solvent mixture of catalyst ink. Using this method, the PGM-free catalyst MEA achieved the current density 44.9 mA cm -2 at 0.9 V iR-free in H 2 /O 2 and 150 mA cm -2 at 0.8 V in H 2 /air, which surpassed the performance targets of US Department of Energy (DOE)for PGM-Free catalyst MEA. The property (solvent composition, dispersion of catalyst and ionomer in an ink), structure (pore structure) and the MEA performance have been characterized using, mercury intrusion porosimetry (MIP), MEA testing. A property-structure-performance relationship has been established.
The dispersing solvent used for fuel cell catalyst ink preparation plays a vital role in establishing the resulting morphology of the electrode layers, which in turn will impact the performance of proton exchange membrane (PEM) fuel cells. In this study, we report the impact of various ionomer dispersion solvents on PEM fuel cell performance and durability; two aqueous (1-propanol/water and 2-propanol/water) and several non-aqueous dispersing solvents (ethylene glycol and 1,2-butanediol) are compared. The cathode catalyst layer (CCL) fabricated using inks prepared with 1-propanol/water (3:1, w/w) exhibited the best initial performance followed by the CCL prepared using ethylene glycol. The CCLs made from non-aqueous ethylene glycol and 1,2-butanediol exhibited the best durability upon accelerated stress testing. Scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy indicated that, after the stress test, the distribution of both the Nafion ionomer and Pt nanoparticles within the CCLs prepared with non-aqueous ionomer dispersions underwent less change than those prepared with aqueous dispersions, which is responsible for the improved durability
Prediction of the catalyst-activated carbon particle sizes of fuel-cell inks remains a critical challenge in enhancing the performance and durability of fuel cells. The performance and structural integrity of the catalyst layers in the cell depend not only on the properties of the ionomer, but also on the carbon supports that host the catalyst. To investigate how these carbon aggregate structures form, we present a model that calculates the cooperative size distributions of ionomer and carbon aggregates in various water/alcohol mixtures and compares those results to available experimental data. Aggregation of both the suspended ionomers and the carbon particles is interwoven as the carbon aggregation depends heavily on the ionic strength of its environment, namely protons dissociating from the ionomer’s sulfonic-acid-group side chains. We demonstrate that the surrounding mixed solvent as well as Nafion TM binder concentration strongly influence the degree of aggregation for carbon particles. The validated model provides a framework for exploring aggregation under a wide range of conditions for various electrochemical-technology inks.
As the production of polymer electrolyte fuel cells expands, novel quality control methods must be invented or adapted in order to support expected rates of production. Ensuring the quality of deposited catalyst layers is an essential step in the fuel cell manufacturing process, as the efficiency of a fuel cell is reliant on the catalyst layer being uniform at both the target platinum loading and the target ionomer content. Implementing a quality control method that is sensitive to these aspects is imperative, as wasting precious metals and other catalyst materials is expensive, and represents a potential barrier to entry into the field for manufacturers experimenting with novel deposition processes. In this work, we analyzed catalyst inks to determine if their ionomer content could be quantized spectroscopically. Attenuated total reflection (ATR) Fourier transform infrared spectroscopic technique was investigated producing a signal proportional to the ionomer content. ATR spectroscopy was able to quantitatively differentiate samples in which the ionomer to carbon mass ratio (I/C) varied between 0.9 and 3.0. The I/C ratio was correlated to the measured ATR signal near the CF 2 vibrational bands located between 1100 cm −1 and 1400 cm −1 . The experimental results obtained constitute a step toward the development of novel quality control methodologies for catalyst inks utilized by the fuel cell industry.
Sandwich structured (SS) composites demonstrate considerable flexural stiffness and high strength-to-weight ratios and can be tailored as functional materials. Historically they have been constrained to specific material types and geometry due to limitations in manufacturing methods. However, employing additive manufacturing (AM), specifically direct ink writing (DIW), can provide an alternative method for making SS composites with complex and controllable micro and mesostructures with multifunctionality targeted at desired mechanical, thermal, and electrical properties. DIW, an extrusion-based AM technique, uses a viscous and thixotropic ink with desired components that, once printed, is cured to obtain the final complex net shape parts. In this paper, a novel hybrid AM technique is employed to manufacture SS composite materials containing bisphenol A-based epoxy core and carbon fiber reinforced polymer (CFRP) face sheets that are fabricated via DIW and vacuum infusion process (VIP), respectfully. We demonstrate that the fabrication of these SS composites can be tailored from a thermosetting material, from which additives and/or various lattice structures can be manufactured to achieve enhanced and desirable mechanical integrity with functional properties. Surface topology and mechanical testing techniques are used to characterize the fabricated hybrid SS composites to study and assess mechanical stability. A rheo-kinetic cure model was developed for the core material to allow for additive manufacturing process requirements while ensuring complete cross-linking for the thermoset-based core material. Because of the ability to obtain relatively small core-thickness and controlled architecture, this method now allows for fabricating layered micro-sandwich structures for realizing further light-weighting in relevant applications.
Direct Ink Writing (DIW) utilizes a wide range of ink formulations to produce desirable 3D-printed structures and properties. Styrene-butadiene rubber (SBR) is an attractive candidate for 3D printing owing to its commercial availability, rheology, excellent mechanical properties, good impact resilience, and chemical stability. The SBR-based sealant was 3D printed in a DIW process, even in an ambient environment. The rheological behavior was assessed and correlated with optimized printing parameters. Important physico-chemical properties of the 3D-printed material were reported showing excellent properties as an elastomer. Finally, this work should expand the potential applications of existing rubber-based materials in additive manufacturing.
Ocean acidification heavily impacts marine ecosystems by reducing calcification. Many coral-algae symbiotic relationships are in jeopardy due to the destruction of coral reefs. Here, a ceramic ink compatible with the direct ink write additive manufacturing technique was formulated and used to print marine compatible structures that could grow algae and restore that relationship. A diacrylate polymer was mixed with calcium carbonate, a material that comprises a coral skeleton, to create a slurry with shear thinning properties. Rheology studies were conducted to confirm printing properties and characterize the slurry. Printed parts demonstrated strong control over print features, including size and infill design. Various infill patterns and percentages were attempted to optimize printability and potential algae growth. Thermogravimetric analysis helped determine a logical burnout and sintering procedure to avoid large cracking. This project developed a printable and sinter-able calcium carbonate ceramic slurry for complex marine-compatible structures and algae growth. This research was conducted in the support of the Eco Reef project.
The report describes the development of scalable manufacturing methods for high-performance, stable perovskite solar modules using flexographic printing. The project developed self-leveling perovskite inks that exploit Marangoni flows to reduce coating defects and improve large-area film uniformity. Bayesian optimization was integrated with high-throughput photoluminescence mapping and photovoltaic measurements to efficiently optimize ink formulations and printing conditions. The resulting printed perovskite solar cells achieved champion power conversion efficiencies above 21.6%, with median efficiencies exceeding 20% across large device batches. At the module scale, printed devices achieved active-area efficiencies up to approximately 17.3% on 25 cm² substrates. The project also demonstrated improved performance and stability using additively patterned interconnections compared with laser-scribed controls. Overall, the work establishes a data-driven, roll-compatible pathway toward high-throughput, low-capital-cost manufacturing of uniform and stable perovskite photovoltaics.
Commercial and experimental fire retardants were screened for possible use wiith acrylic printing inks on aircraft interior sandwich panels. The fire retardants were selected according to their physical properties and thermostabilities. Thermostabilities were determined by thermogravimetric analysis and differential scanning calorimetry. A criterion was then established for selecting the more stable agent. Results show that some of the bromine-containing fire retardants are more thermostable than the acrylic ink, alone, used as a control. Also, the bromine-containing fire retardants yield even better limiting oxygen index values when tested after adding carboxy-terminated butadiene acrylonitrile (CTBN) rubber.
Contacts formed in controllable patterns with metal-based inks. System forms upper metal contact patterns on silicon photovoltaic cells. Uses metallo-organic ink, decomposes when heated, leaving behind metallic, electrically conductive residue in printed area.
Liquid metal (LM) elastomer composites offer promising potential in soft robotics, wearable electronics, and human-machine interfaces. Direct ink write (DIW) 3D printing offers a versatile manufacturing technique capable of precise control over LM microstructures, yet challenges such as interfilament void formation in multilayer structures impact material performance. Here, a DIW strategy is introduced to control both LM microstructure and material architecture. Investigating three key process parameters–nozzle height, extrusion rate, and nondimensionalized nozzle velocity–it is found that nozzle height and velocity predominantly influence filament geometry. The nozzle height primarily dictates the aspect ratio of the filament and the formation of voids. A threshold print height based on filament geometry is identified; below the height, significant surface roughness occurs, and above the ink fractures, which facilitates the creation of porous structures with tunable stiffness and programmable LM microstructure. These porous architectures exhibit reduced density and enhanced thermal conductivity compared to cast samples. When used as a dielectric in a soft capacitive sensor, they display high sensitivity (gauge factor = 9.0), as permittivity increases with compressive strain. These results demonstrate the capability to simultaneously manipulate LM microstructure and geometric architecture in LM elastomer composites through precise control of print parameters, while maintaining geometric fidelity in the printed design.
A separator made of ion conductive ink is produced by additive manufacturing. A micro-battery is produced with the separator made of ion conductive ink located between the battery's anode and cathode. The separator functions to keep the anode and cathode apart and to facilitate the transport of ions to produce an operative micro-battery.
A method can comprise providing an ink comprising reactants, a complexing agent, and a solvent, depositing the ink onto a substrate to form a wet film, drying the wet film to form a precursor layer, and annealing the precursor layer to form a perovskite film. The reactants can comprise a first and a second cation, a first metal, and a first and a second anion, wherein the first and second cations are different from each other, and the first and second anions are different from each other. The complexing agent can comprise a heterocyclic donor material. The perovskite film can comprise a mixed-cation mixed-halide perovskite material, and less than 5% by mass of the complexing agent. The perovskite film can also be formed using a one-step process.
Systems for creating electrodes for polymer electrolyte membrane fuel cells include an XY stage having a heated vacuum table physically coupled to the XY stage. The vacuum table has a working face with a plurality of channels formed therein to communicate vacuum pressure from a port coupled to a vacuum source to the channels. A sheet of perforated heat-conductive material has staggered holes configured to evenly distribute the vacuum pressure from the channels through the perforated sheet. A heat-conductive wire mesh is placed over the perforated sheet, and has openings smaller than the staggered holes such that a membrane material placed on the wire mesh is not deformed by the vacuum pressure. A nanopipette or micropipette coupled to a pump is configured to deposit electrode ink onto an exposed surface of the membrane material as the controller device causes the XY stage to move the vacuum table to control deposition of the electrode ink onto the surface of the membrane material.