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Results for “stretchable electronics”

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.

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141 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Design of Star‐Shaped Trimer Acceptors for High‐Performance (Efficiency > 19%), Photostable, and Mechanically Robust Organic Solar Cells

Abstract High power conversion efficiency (PCE), long‐term stability, and mechanical robustness are prerequisites for the commercial applications of organic solar cells (OSCs). In this study, a new star‐shaped trimer acceptor (TYT‐S) is developed and high‐performance OSCs with a PCE of 19.0%, high photo‐stability (t 80% lifetime = 2600 h under 1‐sun illumination), and mechanical robustness with a crack‐onset strain (COS) of 21.6% are achieved. The isotropic molecular structure of TYT‐S affords efficient multi‐directional charge transport and high electron mobility. Furthermore, its amorphous structure prevents the formation of brittle crystal‐to‐crystal interfaces, significantly enhancing the mechanical properties of the OSC. As a result, the TYT‐S‐based OSCs demonstrate a significantly higher PCE (19.0%) and stretchability (COS = 21.6%) than the linear‐shaped trimer acceptor (TYT‐L)‐based OSCs (PCE = 17.5% and COS = 6.4%) and the small‐molecule acceptor (MYT)‐based OSCs (PCE = 16.5% and COS = 1.3%). In addition, the increased molecular size of TYT‐S, relative to that of MYT and dimer (DYT), suppresses the diffusion kinetics of the acceptor molecules, substantially improving the photostability of the OSCs. Finally, to effectively demonstrate the potential of TYT‐S, intrinsically stretchable (IS)‐OSCs are constructed. The TYT‐S‐based IS‐OSCs exhibit high device stretchability (strain at PCE 80% = 31%) and PCE of 14.4%.

Chemistry↗
DOE OSTI2016

Coaxial printing method for directly writing stretchable cable as strain sensor

Through applying the liquid metal and elastomer as the core and shell materials, respectively, a coaxial printing method is being developed in this work for preparing a stretchable and conductive cable. When liquid metal alloy eutectic Gallium-Indium is embedded into the elastomer matrix under optimized control, the cable demonstrates well–posed extreme mechanic performance, under stretching for more than 350%. Under developed compression test, the fabricated cable also demonstrates the ability for recovering original properties due to the high flowability of the liquid metal and super elasticity of the elastomeric shell. The written cable presents high cycling reliability regarding its stretchability and conductivity, two properties which can be clearly predicted in theoretical calculation. This work can be further investigated as a strain sensor for monitoring motion status including frequency and amplitude of a curved object, with extensive applications in wearable devices, soft robots, electronic skins, and wireless communication.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Glass Transition Phenomenon for Conjugated Polymers

Conjugated polymers are emerging as promising building blocks for a broad range of modern applications including skin-like electronics, wearable optoelectronics, and sensory technologies. In the past three decades, the optical and electronic properties of conjugated polymers have been extensively studied, while their thermomechanical properties, especially the glass transition phenomenon which fundamentally represents the polymer chain dynamics, have received much less attention. Currently, there is a lack of design rules that underpin the glass transition temperature of these semirigid conjugated polymers, putting a constraint on the rational polymer design for flexible stretchable devices and stable polymer glass that is needed for the devices' long-term morphology stability. In this review article, the glass transition phenomenon for polymers, glass transition theories, and characterization techniques are first discussed. Furthermore, previous studies on the glass transition phenomenon of conjugated polymers are reviewed and a few empirical design rules are proposed to fine-tune the glass transition temperature for conjugated polymers. The review paper is finished with perspectives on future directions on studying the glass transition phenomena of conjugated polymers. The goal of this perspective is to draw attention to challenges and opportunities of controlling, predicting, and designing polymeric semiconductors, specifically to accommodate their end use.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Anisotropic Phonon Response of Few-Layer PdSe 2 under Uniaxial Strain

PdSe 2 , an emerging 2D material with a novel anisotropic puckered pentagonal structure, has attracted growing interest due to its layer-dependent electronic bandgap, high carrier mobility, and good air stability. In this work, a detailed Raman spectroscopic study of few-layer PdSe 2 (two to five layers) under the in-plane uniaxial tensile strain up to 3.33% is performed. Two of the prominent PdSe 2 Raman peaks are influenced differently depending on the direction of strain application. Additionally, the A g 1 mode redshifts more than the A g 3 mode when the strain is applied along the a -axis of the crystal, while the A g 3 mode redshifts more than the A g 1 mode when the strain is applied along the b -axis. Such an anisotropic phonon response to strain indicates directionally dependent mechanical and thermal properties of PdSe 2 and also allows the identification of the crystal axes. The results are further supported using first-principles density-functional theory. Interestingly, the near-zero Poisson’s ratios for few-layer PdSe 2 are found, suggesting that the uniaxial tensile strain can easily be applied to few-layer PdSe 2 without significantly altering their dimensions at the perpendicular directions, which is a major contributing factor to the observed distinct phonon behavior. The findings pave the way for further development of 2D PdSe 2 -based flexible electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Printing thermoelectric inks toward next-generation energy and thermal devices

The ability of thermoelectric (TE) materials to convert thermal energy to electricity and vice versa highlights them as a promising candidate for sustainable energy applications. Despite considerable increases in the figure of merit zT of thermoelectric materials in the past two decades, there is still a prominent need to develop scalable synthesis and flexible manufacturing processes to convert high-efficiency materials into high-performance devices. Scalable printing techniques provide a versatile solution to not only fabricate both inorganic and organic TE materials with fine control over the compositions and microstructures, but also manufacture thermoelectric devices with optimized geometric and structural designs that lead to improved efficiency and system-level performances. In this review, we aim to provide a comprehensive framework of printing thermoelectric materials and devices by including recent breakthroughs and relevant discussions on TE materials chemistry, ink formulation, flexible or conformable device design, and processing strategies, with an emphasis on additive manufacturing techniques. Additionally, we review recent innovations in the flexible, conformal, and stretchable device architectures and highlight state-of-the-art applications of these TE devices in energy harvesting and thermal management. Perspectives of emerging research opportunities and future directions are also discussed. While this review centers on thermoelectrics, the fundamental ink chemistry and printing processes possess the potential for applications to a broad range of energy, thermal and electronic devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Skin-like low-noise elastomeric organic photodiodes

Stretchable optoelectronics made of elastomeric semiconductors could enable the integration of intelligent systems with soft materials, such as those of the biological world. Organic semiconductors and photodiodes have been engineered to be elastomeric; however, for photodetector applications, it remains a challenge to identify an elastomeric bulk heterojunction (e-BHJ) photoactive layer that combines a low Young’s modulus and a high strain at break that yields organic photodiodes with low electronic noise values and high photodetector performance. Here, a blend of an elastomer, a donor-like polymer, and an acceptor-like molecule yields a skin-like e-BHJ with a Young’s modulus of a few megapascals, comparable to values of human tissues, and a high strain at break of 189%. Elastomeric organic photodiodes based on e-BHJ photoactive layers maintain low electronic noise current values in the tens of femtoamperes range and noise equivalent power values in the tens of picowatts range under at least 60% strain.

42 ENGINEERING↗
DOE OSTI2022

Sequentially regular polymer acceptors featuring flexible spacers for high-performance and mechanically robust all-polymer solar cells

Developing high-performance and mechanically robust polymer solar cells (PSCs) is crucial for realizing wearable power sources. While efficient all-polymer solar cells (all-PSCs) can be fabricated from polymerized small-molecule acceptors (PSMAs) with high optical absorption and electron mobilities, they still show limited mechanical robustness. Here, we achieve highly efficient and mechanically robust all-PSCs by designing a PSMA (PYFS-Reg) containing sequence-regular flexible spacers (FSs). The regular incorporation of the FS units into PSMAs is essential in simultaneously improving the electrical and mechanical properties of blend films. As a result, all-PSCs featuring PYFS-Reg achieve a high power conversion efficiency (PCE = 16.1%) and stretchability (crack onset strain (COS) = 22.4%), outperforming PSMAs without FSs (i.e., PYBDT, PCE = 12.6% and COS = 11.7%) or with randomly distributed FSs (i.e., PYFS-Ran, PCE = 12.2% and COS = 18.1%). Importantly, these all-PSCs are fabricated by an environmentally benign, non-halogenated solvent process. To further demonstrate their feasible applications in wearable devices, we construct intrinsically stretchable (IS) all-PSCs by using PYFS-Reg-based active layers, which exhibit a high PCE (10.6%) and excellent device stretchability (strain at PCE 80% = 36.7%).

14 SOLAR ENERGY↗
DOE OSTI2025

High-voltage water-scarce hydrogel electrolytes enable mechanically safe stretchable Li-ion batteries

Soft Li-ion batteries, based on conventional organic electrolytes, face performance degradation challenges due to moisture penetration and safety concerns due to possible leakage of toxic fluorine compounds and flammable solvents under mechanical damage. We design a water-scarce hydrogel electrolyte with fluorine-free lithium salt to achieve wide electrochemical stability window (up to 3.11 volts) in ambient air without hermetic packaging while balancing high stretchability (1348%), ion conductivity (41 millisiemens per centimeter), and self-healing capabilities for mechanically and chemically safe stretchable Li-ion batteries. Molecular synergy between hydrophilicity and lithiophilicity of zwitterionic polymer backbone is revealed by molecular dynamics simulations. The battery exhibits capacity retention under harsh mechanical stresses—enduring stretching, twisting, folding, and multiple through-punctures by a needle—while self-healing from repeated through cuts by a razor blade. Stable ambient operation for 1 month over 500 charge-discharge cycles (average coulomb efficiency, 95%) is achieved. A prototype self-healing electronic system with embedded soft batteries demonstrates practical application as a durable embodied energy source.

Science & Technology - Other Topics↗
DOE OSTI2019

Stretchable sensors for environmental monitoring

The development of flexible and stretchable sensors has been receiving increasing attention in recent years. In particular, stretchable, skin-like, wearable sensors are desirable for a variety of potential applications such as personalized health monitoring, human-machine interfaces, and environmental sensing. In this paper, we review recent advancements in the development of mechanically flexible and stretchable sensors and systems that can be used to quantitatively assess environmental parameters including light, temperature, humidity, gas, and pH. We discuss innovations in the device structure, material selection, and fabrication methods which explain the stretchability characteristics of these environmental sensors and provide a detailed and comparative study of their sensing mechanisms, sensor characteristics, mechanical performance, and limitations. Finally, we provide a summary of current challenges and an outlook on opportunities for possible future research directions for this emerging field.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

High-efficiency stretchable light-emitting polymers from thermally activated delayed fluorescence

Stretchable light-emitting materials are the key components for realizing skin-like displays and optical biostimulation. All the stretchable emitters reported to date, to the best of our knowledge, have been based on electroluminescent polymers that only harness singlet excitons, limiting their theoretical quantum yield to 25%. Here we present a design concept for imparting stretchability onto electroluminescent polymers that can harness all the excitons through thermally activated delayed fluorescence, thereby reaching a near-unity theoretical quantum yield. We show that our design strategy of inserting flexible, linear units into a polymer backbone can substantially increase the mechanical stretchability without affecting the underlying electroluminescent processes. As a result, our synthesized polymer achieves a stretchability of 125%, with an external quantum efficiency of 10%. Additionally, we demonstrate a fully stretchable organic light-emitting diode, confirming that the proposed stretchable thermally activated delayed fluorescence polymers provide a path towards simultaneously achieving desirable electroluminescent and mechanical characteristics, including high efficiency, brightness, switching speed and stretchability as well as low driving voltage.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Recent Trends and Innovation in Additive Manufacturing of Soft Functional Materials

The growing demand for wearable devices, soft robotics, and tissue engineering in recent years has led to an increased effort in the field of soft materials. With the advent of personalized devices, the one-shape-fits-all manufacturing methods may soon no longer be the standard for the rapidly increasing market of soft devices. Recent findings have pushed technology and materials in the area of additive manufacturing (AM) as an alternative fabrication method for soft functional devices, taking geometrical designs and functionality to greater heights. For this reason, this review aims to highlights recent development and advances in AM processable soft materials with self-healing, shape memory, electronic, chromic or any combination of these functional properties. Furthermore, the influence of AM on the mechanical and physical properties on the functionality of these materials is expanded upon. Additionally, advances in soft devices in the fields of soft robotics, biomaterials, sensors, energy harvesters, and optoelectronics are discussed. Lastly, current challenges in AM for soft functional materials and future trends are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Elastomeric vitrimers from designer polyhydroxyalkanoates with recyclability and biodegradability

Cross-linked elastomers are stretchable materials that typically are not recyclable or biodegradable. Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) are soft and ductile, making these bio-based polymers good candidates for biodegradable elastomers. Elasticity is commonly imparted by a cross-linked network structure, and covalent adaptable networks have emerged as a solution to prepare recyclable thermosets via triggered rearrangement of dynamic covalent bonds. Here, we develop biodegradable and recyclable elastomers by chemically installing the covalent adaptable network within biologically produced mcl-PHAs. Specifically, an engineered strain of Pseudomonas putida was used to produce mcl-PHAs containing pendent terminal alkenes as chemical handles for postfunctionalization. Thiol-ene chemistry was used to incorporate boronic ester (BE) cross-links, resulting in PHA-based vitrimers. mcl-PHAs cross-linked with BE at low density (<6 mole %) affords a soft, elastomeric material that demonstrates thermal reprocessability, biodegradability, and denetworking at end of life. The mechanical properties show potential for applications including adhesives and soft, biodegradable robotics and electronics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Unraveling the Photovoltaic, Mechanical, and Microstructural Properties and Their Correlations in Simple Poly(3‐pentylthiophene) Solar Cells

Abstract The power conversion efficiency of polythiophene organic solar cells is constantly refreshed. Despite the renewed device efficiency, very few efforts have been devoted to understanding how the type of electron acceptor alters the photovoltaic and mechanical properties of these low‐cost solar cells. Herein, the authors conduct a thorough investigation of photovoltaic and mechanical characteristics of a simple yet less‐explored polythiophene, namely poly(3‐pentylthiophene) (P3PT), in three different types of organic solar cells, where ZY‐4Cl, PC 71 BM, and N2200 are employed as three representative acceptors, respectively. Compared with the reference poly(3‐hexylthiophene) (P3HT)‐based solar cells, P3PT‐based devices, all perform more efficiently. Particularly, the P3PT:ZY‐4Cl blend exhibits the highest efficiency (ca. 10%) among the six combinations and outperforms the prior top‐performance system P3HT:ZY‐4Cl. Furthermore, the blend films based on N2200 exhibit a high crack‐onset strain of ∼38% on average, which is approximately 15‐ and 17‐times higher than those of ZY‐4Cl and PC 71 BM, respectively. The microstructural origins for the above difference are well elucidated by detailed grazing incidence X‐ray scattering and microscopy analysis. This work not only underlines the potential of P3PT in prolific solar cell research but also demonstrates the superior tensile properties of polythiophene‐based all‐polymer blends for the preparation of stretchable solar cells.

Polymer Science↗
DOE OSTI2023

A flexible polymer-based luminescent ink for combined thermographic phosphors and digital image correlation (TP+DIC)

Recent work on the development of integrated thermographic phosphors and digital image correlation (TP+DIC) for combined thermal–mechanical measurements has revealed the need for a flexible, stretchable phosphor coating for metal surfaces. Herein, we coat stainless steel substrates with a polymer-based phosphor ink in a DIC speckle pattern and demonstrate that the ink remains well bonded under substrate deformation. In contrast, a binderless phosphor DIC coating produced via aerosol deposition (AD) partially debonded from the substrate. DIC calculations reveal that the strain on the ink coating matches the strain on the substrate within 4% error at the highest substrate loads (0.05 mm/mm applied substrate strain), while the strain on the AD coating remains near 0 mm/mm as the substrate deforms. Spectrally resolved emission from the phosphor is measured through the transparent binder throughout testing, and the ratio method is used to infer temperature with an uncertainty of 1.7 °C. In conclusion, this phosphor ink coating will allow for accurate, non-contact strain and temperature measurements of a deforming surface.

36 MATERIALS SCIENCE↗