Low Transition Temperature Research Articles

Microstructure evolution and mechanical properties of β/γ-TiAl alloy during high-rate near-isothermal multidirectional forging

The microstructure of β/γ-TiAl alloy was characterized and analyzed in various deformation regions during a high-rate near-isothermal multidirectional forging (HR-NIMDF) process in this study. The results indicate that the localized precipitation of the B2 phase occurs within the large lamella microstructure through DRX and heterogeneous exsolution decomposition mechanism in the stagnant zone. The majority of mixed fine-grained microstructures (α2/γ/B2), with a grain diameter smaller than 1 μm, were formed under an appropriate stress-temperature coupling field. In the central region of the large deformation zone, a small twisted lamellar microstructure with low B2 phase content is observed, suggesting that HR-NIMDF can efficiently decompose the (α2/γ) lamellar structure and achieve refined grain microstructures. After undergoing HR-NIMDF, the β/γ-TiAl alloy exhibits a low tough-brittle transition temperature and an elongation of 7 % at 650 °C, with an ultimate tensile strength of 862.6 MPa. At 700 °C, the elongation increases to 55.4 %, while the ultimate tensile strength decreases to 653.8 MPa. Moreover, this study demonstrates that when the plastic deformation degree is insufficient and the adiabatic warming effect is relatively pronounced, significant precipitation of the B2 phase leads to a reduction in DRX extent within the material, ultimately resulting in the formation of large residual (α2/γ) lamellar microstructure. The unsynchronized thermal-force coupling relationship between the precipitation of the B2 phase and DRX holds significant implications for advancing and refining the thermoplastic deformation process of β/γ-TiAl alloy.

Low-Temperature Nanosecond Laser Process of HZO-IGZO FeFETs toward Monolithic 3D System on Chip Integration.

Ferroelectric field-effect transistors (FeFETs) are increasingly important for in-memory computing and monolithic 3D (M3D) integration in system-on-chip (SoC) applications. However, the high-temperature processing required by most ferroelectric memories can lead to thermal damage to the underlying device layers, which poses significant physical limitations for 3D integration processes. To solve this problem, the study proposes using a nanosecond pulsed laser for selective annealing of hafnia-based FeFETs, enabling precise control of heat penetration depth within thin films. Sufficient thermal energy is delivered to the IGZO oxide channel and HZO ferroelectric gate oxide without causing thermal damage to the bottom layer, which has a low transition temperature (<250 °C). Using optimized laser conditions, a fast response time (<1 µs) and excellent stability (cycle >106, retention >106 s) are achieved in the ferroelectric HZO film. The resulting FeFET exhibited a wide memory window (>1.7V) with a high on/off ratio (>105). In addition, moderate ferroelectric properties (2·Pr of 14.7 µCcm-2) and pattern recognition rate-based linearity (potentiation: 1.13, depression: 1.6) are obtained. These results demonstrate compatibility in HZO FeFETs by specific laser annealing control and thin-film layer design for various structures (3D integrated, flexible) with neuromorphic applications.

Room-temperature superelasticity in Mg–Sc shape memory alloys revealed by first-principles calculations

The discovery of the Mg–Sc shape memory alloy system has become a milestone in the development of lightweight shape memory alloys. However, for the application scenarios with the highest demand at room temperature, the Mg–Sc alloy faces problems such as excessively low phase transition temperatures and poor room-temperature superelasticity, directly hindering the practical application of this new type of lightweight memory alloy. In this work, Mg–Sc based shape memory alloys with exceptional room temperature superelasticity have been screened for the first time utilizing Tm, phase transformation strain, and stress-strain curves. Co and Ge are selected as the most promising elements for improving Mg–Sc based alloys at room temperature. Furthermore, the mechanism behind the superelasticity of Mg–Sc alloy has been systematically unveiled and the average rate of energy change per unit time of the alloys was calculated for the first time. Co doped Mg–Sc based alloys exhibited the lowest variations in the average rate of energy change per unit time, Helmholtz free energy, and M1, along with a higher charge density between Co and Sc atoms. Additionally, a coupling effect between the d orbital of Co and Sc electrons and a lowered Fermi level was observed. These findings demonstrate that Co doping in Mg–Sc based alloys significantly reduces the superelastic hysteresis area and transformation driving force, and increases Tm and strain, thereby enhancing superelasticity. This research guides further studies and the design of new Mg–Sc based lightweight SMAs with outstanding superelasticity at room temperature.

Synthesis and characterization of absorption-enhanced alumina solid particle materials for direct irradiation solar-thermal conversion

Based on solar-thermal application more than 1000 °C, a novel combination of sol-gel synthesis and stepwise calcination to prepare metal-ion doped alumina composite particles as heat transfer media were proposed, enhancing solar energy absorption and lowering preparation temperature. Investigations focused on the elemental distribution, phase composition, oxidation states, optical properties and thermal stability of the composites, which were doped with Cr, Co, Cu, Fe, and Mn metal ions in a 100:5 M ratio. The first-principles calculations elucidate the mechanism behind the impact of transition metal ions on alumina’s optical properties. Results show that introducing a small quantity of metal atoms results in new impurity energy levels and electron states around EF = 0. Specifically, the band gap energy of Cu- and Mn–Al2O3 decreases from 6.017 eV to 4.464 eV and 2.170 eV, respectively. Correspondingly, the absorptivity of these composite particles increases from around 20 %–76.6 %. And Tauc analysis indicates a decrease in the optical band gap of the particle materials from 5.37 eV to a range of 2.88–4.90 eV. Additionally, doping with Mn, Fe, and Cu accelerates the in-situ formation of α-Al2O3 crystals, with a phase transition temperature below 1000 °C and a crystallinity exceeding 93 %. Thermal stability tests show that the particles are highly stable, exhibiting a mere 0.49 % mass change between 30 °C and 1200 °C. The stepwise inert annealing strategy and metal-iron doping positively influence the optical performance of alumina, synthesizing long-term high-temperature stable alumina ceramic particles with absorptance enhancement and a low α-Al2O3 phase transition temperature. These attributes make a favorable choice for solar-thermal applications in direct irradiation.

Preparation of CMC-poly(N-isopropylacrylamide) semi-interpenetrating hydrogel with temperature-sensitivity for water retention

The CMC-PNIPAM hydrogel with semi-interpenetrating structure and temperature-sensitivity was prepared by in-situ polymerization of N-isopropylacrylamide (NIPAM) in sodium carboxymethylcellulose (CMC) solution at room temperature. The mass ratio of CMC to NIPAM was a key factor influencing the network structure and property of CMC-PNIPAM hydrogel. The low critical phase transition temperature (LCST) of CMC-PNIPAM hydrogels increased from 34.4 °C to 35.8 °C with the mass ratio of CMC to NIPAM rising from 0 to 1.2. The maximum compressive stress of CMC-PNIPAM hydrogel reached to 26.7 kPa and the relaxation elasticity was 52 % at strain of 60 %. The viscoelasticity of CMC-PNIPAM hydrogel was consistent with the generalized Maxwell model. The maximum swelling ratio in deionized water was 170.25 g·g−1 (dried hydrogel) with swelling rate of 2.57 g·g−1·min−1 at 25 °C. CMC-PNIPAM hydrogel hardly absorbed water above LCST, but the swollen hydrogel could release water at the rate of 0.36 g·g−1·min−1 once exceeding LCST. The test of water retention showed that soil mixed with 2 wt% dried CMC-PNIPAM hydrogel could retain 13.08 wt% water after 30 days at 25 °C that was 4.4 times than that of controlled soil without CMC-PNIPAM hydrogel. The semi-interpenetrating CMC-PNIPAM hydrogel showed a potential to conserve water responding to temperature.

Effects of Particle Size Distribution on the Physicochemical, Functional, and Structural Properties of Alfalfa Leaf Powder

To explore the effects of particle size distribution on its physicochemical, functional, and structural properties, alfalfa leaf powders with mean particle sizes (D50) of 506.1, 246.3, 209.8, 92.01, and 20.68 μm were prepared by sieving. The physicochemical, functional, and structural properties of alfalfa were compared, and correlation and principal component analyses were conducted. As the D50 of alfalfa leaf decreased, the bulk density, tap density, and the swelling capacity increased first and then decreased, but the compressibility, transition temperature, and melting temperature exhibited an opposite trend. The solubility, lightness, and inhibition of angiotensin-converting enzymes and tyrosinase were enhanced. Specifically, the alfalfa leaf with a D50 of 209.8 μm exhibited a higher bulk density and swelling capacity and a lower compressibility, transition temperature, and melting temperature. The alfalfa leaf with a D50 of 20.68 μm presented better solubility, lightness, and inhibition of angiotensin-converting enzymes and tyrosinase. Additionally, the surface roughness and the number of surface hydroxyls improved and the crystallinity index decreased, but the type of surface functional groups was unchanged. These changes in microstructure can provide an explanation for the trend of the physicochemical and functional properties. Moreover, based on the results of the correlation analysis and principal component analysis, it can be concluded that there are strong correlations among the particle size, physicochemical properties, and functional properties of alfalfa leaf. Overall, this conclusion can help determine the appropriate grinding particle size range for alfalfa leaf in different functional food products.

Shape Programmable and Multifunctional Soft Textile Muscles for Wearable and Soft Robotics

Textiles are promising candidates for use in soft robots and wearable devices due to their inherent compliance, high versatility, and skin comfort. Planar fluidic textile‐based actuators exhibit low profile and high conformability, and can seamlessly integrate additional components (e.g., soft sensors or variable stiffness structures [VSSs]) to create advanced, multifunctional smart textile actuators. In this article, a new class of programmable, fluidic soft textile muscles (STMs) that incorporate multilayered silicone sheets with embedded fluidic channels is introduced. The STMs are scalable and fabricated by apparel engineering techniques, offering a fabrication approach able to create large‐scaled multilayered structures that can be challenging for current microfluidic bonding methods. They are also highly automation compatible due to no manual insertion of elastic tubes/bladders into textile structures. Liquid metal is employed for creating fluidic channels. It is not only used for actuation but also used as channels for additional features such as soft piezoresistive sensors with enhanced sensitivity to STMs’ pressure‐induced elongation, or VSSs of either low‐melting‐point alloys or a new thermo‐responsive epoxy with low viscosity and transition temperature. The STMs hold promising prospects for soft robotic and wearable applications, which is demonstrated by an example of a textile‐based wearable 3D skin‐stretch haptic interface.

Two‐Photon Direct Laser Writing of pNIPAM Actuators in Microchannels for Dynamic Microfluidics

Microfluidic tools enable to investigate and manipulate various chemical and biological processes at small scales. As a result, it finds widespread applications in lab‐on‐chip devices, drug delivery systems, or miniaturized cell cultures. However, microfluidic devices are still limited in their flexibility and are often designed to fulfill a single functionality. Moreover, technologies to introduce dynamic functionalities with high precision and at high resolution after the development of a continuous phase microfluidic chip remain scarce. Herein, two‐photon polymerization direct laser writing is introduced as a suitable approach to equip continuous phase microfluidic chips with structurally defined thermoresponsive poly(N‐isopropyl‐acrylamide) (pNIPAM) microactuators. Harnessing the lower critical phase transition temperature of pNIPAM, and upon controlling specific design parameters, the efficient catch and release of polystyrene beads of different sizes using a pNIPAM micropillar brush array is demonstrated. Moreover, a biocompatible pNIPAM microgripper array is designed to subsequently capture and release differently sized (single) cell populations. Overall, the method offers great flexibility and a high degree of freedom toward the fabrication of dynamic microfluidic devices with great adaptability to experimental conditions in real time.

A Low Transition Temperature Mixture-based viscosupplementation complemented with celecoxib for osteoarthritis treatment

Viscosupplementation consists of hyaluronic acid (HA) intra-articular injections, commonly applied for osteoarthritis treatment while non-steroidal anti-inflammatory drugs (NSAIDs) are widely administered for pain relief. Here, HA and a NSAID (celecoxib) were combined in a formulation based on a low transition temperature mixture (LTTM) of glycerol:sorbitol, reported to increase celecoxib’s solubility, thus rendering a potential alternative viscosupplement envisioning enhanced therapeutic efficiency. The inclusion of glucosamine, a cartilage precursor, was also studied. The developed formulations were assessed in terms of rheological properties, crucial for viscosupplementation: the parameters of crossover frequency, storage (G’) and loss (G’’) moduli, zero-shear-rate viscosity, stable viscosity across temperatures, and shear thinning behaviour, support viscoelastic properties suitable for viscosupplementation. Additionally, the gels biocompatibility was confirmed in chondrogenic cells (ATDC5). Regarding drug release studies, high and low clearance scenarios demonstrated an increased celecoxib (CEX) release from the gel (6 to 73-fold), compared to dissolution in PBS. The low clearance setup presented the highest and most sustained CEX release, highlighting the importance of the gel structure in CEX delivery. NMR stability studies over time demonstrated the LTTM+HA+CEX (GHA+CEX) gel as viable candidate for further in vivo evaluation. In sum, the features of GHA+CEX support its potential use as alternative viscosupplement.

Facile and dynamic infrared modulation of durable VO2/CuI films for smart window applications

Vanadium dioxide (VO2) has been widely investigated as a smart window material due to its excellent thermochromic properties. However, with the increasing abundance of studies on VO2-based structures, its low solar modulation capability, environmental durability and high phase transition temperature have limited its commercial applications. Finding a simple way to solve the above problems simultaneously remains challenging. Here, we propose a bilayer structure combining VO2 and a transparent conductive material, copper iodide (CuI), for functional integration of thermochromic smart windows. The CuI layer is used as an anti-reflective layer and a protective layer to ensure high solar modulation capability (ΔTsol=15.41 %) and good expected service life (ESL=27 years), while realizing the dynamic modulation of infrared spectra at room temperature by Joule heating. This facile structure with overall performance offers a new possibility for the commercialization of VO2-based smart windows and room temperature dynamic modulation of infrared devices.

Annual evaluation of the visual-thermal comfort and energy performance of thermotropic glazing in a reference office room of China

Hydrogel-based thermotropic glazing, which achieves the dynamic characteristics by maneuvering the light-scattering behaviors, has a great potential in improving building energy performance, visual and thermal comfort. The visual-thermal comfort and energy performance of the thermotropic glazing with different transition temperature was evaluated by using an experimental validated building performance simulation model. The performance of the thermotropic glazing was compared with conventional double-clear glazing and low-emissivity double glazing under five cities within the five major climate zones across China. The objective is to comprehensively understand the applicability of the thermotropic glazing in different climatic conditions of China as well as to determine the optimal transition temperature. The results showed that: (1) The thermotropic glazing with a transition temperature of 30 °C could achieve better energy performance, visual and thermal comfort in Xiamen, Nanjing, and Kunming. (2) Low transition temperature is not an essential requirement for the application of the thermotropic glazing, which could result in increasing energy use intensity and this effect is more significant in colder regions. (3) The thermotropic glazing could contribute to building energy savings (up to 16.3% and 2.3% i.e., in Xiamen) compared with conventional double-clear glazing and low-emissivity double glazing with low SHGC. (4) The thermotropic glazing applied in Xiamen, Nanjing and Kunming could obtain better visual and thermal comfort (i.e., increase of the desired range of illuminance sUDI500–2000lux, is up to 85.19% and a promotion of 29.18% in time proportion of desirable thermal comfort in Kunming) when compared with low-emissivity double glazing and conventional double-clear glazing.

Low-temperature cluster spin glass transition in the single-domain NiCr2O4 nanoparticles

NiCr2O4 nanoparticles with average particle size ∼15 nm, a single-domain size maintains the bulk canted antiferromagnetic ground state, were synthesized by a microwave combustion method. The magnetic behavior was carefully investigated by static and dynamic magnetic susceptibility measurements. In addition to a spin-glass-like behavior below paramagnetic-ferrimagnetic transition at T C, the NiCr2O4 nanoparticles demonstrate a low-temperature cluster spin glass transition below the spin canting transition T S, which manifests itself as a magnetic anomaly peak around ∼12 K (at 100 Oe) in the zero-field cooled magnetization with a relatively stronger field dependence in a ‘de Almeida-Thouless’ line for spin glasses. The AC susceptibility analyses in different approaches demonstrate a larger relative peak temperature variation per frequency decade and a longer characteristic relaxation time in the order of 0.04 and 10−7 s, against 0.01 and 10−9 s for the high-temperature blocking, indicating the slow spin dynamics for the low-temperature cluster glassy phase. A field-temperature magnetic phase diagram is proposed for the single-domain NiCr2O4 nanoparticles.

Towards Room Temperature Thermochromic Coatings with controllable NIR-IR modulation for solar heat management & smart windows applications

Solar heat management & green air-conditioning are among the major technologies that could mitigate heat islands phenomenon while minimizing significantly the CO2 global foot-print within the building & automotive sectors. Chromogenic materials in general, and thermochromic smart coatings especially are promising candidates that consent a noteworthy dynamic solar radiation Infrared (NIR-IR) regulation and hence an efficient solar heat management especially with the expected increase of the global seasonal temperature. Within this contribution, two major challenging bottlenecks in vanadium oxide based smart coatings were addressed. It is validated for the first time that the NIR-IR modulation of the optical transmission (∆TTRANS = T(T〈TMIT) − T(T〉TMIT) of Vanadium oxide based smart coatings can be controlled & tuned. This upmost challenging bottle-neck controllability/tunability is confirmed via a genuine approach alongside to a simultaneous drastic reduction of the phase transition temperature TMIT from 68.8 °C to nearly room temperature. More precisely, a substantial thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of standard pure VO2 thin films but with a far lower transition temperature, is reported. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control & tunability of the optical transmission modulation in the NIR-IR (∆TTRANS) via the nano-scaled thickness’ control of the intermediate Vanadium layer. In addition, the control of ∆TTRANS is accompanied by a tremendous diminution of the thermochromic transition temperature from the elevated bulk value of 68.8 °C to the range of 27.5–37.5 ºC. The observed remarkable and reversible thermochromism in such multilayered nano-scaled system of V2O5/V/V2O5 is likely to be ascribed to a noteworthy interfacial diffusion, and an indirect doping by alkaline ions diffusing from the borosilicate substrate. It is hoped that the current findings would contribute in advancing thermochromic smart window technology and their applications for solar heat management in glass windows in general, skyscraper especially & in the automotive industry. If so, this would open a path to a sustainable green air-conditioning with zero-energy input.

Efficient polarization-insensitive quasi-BIC modulation by VO2 thin films.

Bound states in the continuum (BIC) offer great design freedom for realizing high-quality factor metasurfaces. By deliberately disrupting the inherent symmetries, BIC can degenerate into quasi-BIC exhibiting sharp spectra with strong light confinement. This transformation has been exploited to develop cutting-edge sensors and modulators. However, most proposed quasi-BICs in metasurfaces are composed of unit cells with Cs symmetry that may experience performance degradation due to polarization deviation, posing challenges in practical applications. Addressing this critical issue, our research introduces an innovative approach by incorporating metasurfaces with C4v unit cell symmetry to eliminate polarization response sensitivity. Vanadium Dioxide (VO2) is a phase-change material with a relatively low transition temperature and reversibility. Here, we theoretically investigate the polarization-insensitive quasi-BIC modulation in Si-VO2 hybrid metasurfaces. By introducing defects into metasurfaces with Cs, C4, and C4v symmetries, we enable the emergence of quasi-BICs characterized by strong Fano resonance in their transmission spectra. Via numerically calculating the multipole decomposition, distinct dominant multipoles for different quasi-BICs are identified. A comprehensive investigation into the polarization responses of these structures under varying directions of linearly polarized light reveals the superior polarization-independent characteristics of metasurfaces with C4 and C4v symmetries, a feature that ensures the maintenance of maximum resonance peaks irrespective of polarization direction. Utilizing the polarization-insensitive quasi-BIC, we thus designed two different Si-VO2 hybrid metasurfaces with C4v symmetry. Each configuration presents complementary benefits, leveraging the VO2 phase transition's loss change to facilitate efficient modulation. Our quantitative calculation indicates notable achievements in modulation depth, with a maximum relative modulation depth reaching up to 342%. For the first time, our research demonstrates efficient modulation using polarization-insensitive quasi-BICs in designed Si-VO2 hybrid metasurfaces, achieving identical polarization responses for quasi-BIC-based applications. Our work paves the way for designing polarization-independent quasi-BICs in metasurfaces and marks a notable advancement in the field of tunable integrated devices.

Low transition temperature mixture-based extraction of 14 pesticides from tomato samples and their high-performance liquid chromatography-tandem mass spectrometry analysis

The extensive use of pesticides to control pest infestations has led to the development of analytical methods to determine pesticide residues in food matrices to prevent food exposure. However, most developed analytical methods do not consider impact on the environment in terms of the toxicity of the chemicals used and the amount of waste produced. An environmentally-friendly method, based on a miniaturized matrix solid-phase dispersion followed by high-performance liquid chromatography-tandem mass spectrometry, for the analysis of fourteen pesticides in tomatoes, was exploited. For the recovery of pesticides from tomato samples, a low transition temperature mixture (LTTM), containing choline chloride and sesamol 1:3 molar ratio, was employed. Extraction parameters like sample-to-dispersant ratio, extraction solvent volume and LTTM volume were optimized through a Box-Behnken design. The 1:4 sample-to-dispersant ratio, 900 µL of ethanol as extraction solvent and 50 µL of LTTM ensured the best result considering the pesticides' peak areas. The optimized analytical method was validated obtaining the following results: linearity range was between LOQ and 5 mg kg−1 with a minimum R2 of 0.9944 for tebufenozide, values in the range of 0.001–0.023 and 0.004–0.076 mg kg−1 were obtained for LOD and LOQ respectively, while peak areas intra-day and inter-day repeatability were maximum of 10.19 and 9.15 %, respectively. The analytical method was then applied to real samples studying whole, pulp and peel tomato pool.The analysis of whole and tomato pulp revealed the presence of seven and eight of the fourteen investigated pesticides, respectively. However, their concentration was lower than the limit of quantification. In tomato peel, five pesticides, namely dimethomorph, methoxyfenozide, pyraclostrobin, pyriproxyfen, and spiromesifen were quantified and their concentrations were below maximum residue levels.

An approach for obtaining thermochromic smart windows with excellent performance and low phase transition temperature based on VO2/tungsten-doped VO2/VO2 composite structure

Tungsten-doped vanadium dioxide (W-VO2) has a low phase transition temperature (Tc), but the poor thermochromic properties hinders its application in the field of smart windows. In this work, we proposed and fabricated VO2(x nm)/W-VO2(x nm)/VO2(x nm) composite films with different thickness (x = 10, 12, 15 and 20) on quartz glass substrate by pulsed laser deposition. The bottom VO2 layer was served as buffer layer to improve the crystallinity of W-VO2 layer, while the top VO2 layer was to strengthen the thermochromic properties of the composite films. With the increase of x from 10 to 20, XRD and SEM results suggested that the crystallinity and grain morphology of the obtained composite films can be largely regulated. In particular, when x = 12, the luminous transmittance (Tlum) and solar modulation ability (ΔTsol) are as high as 61.1 % and 8.0 %, respectively, while maintaining a low Tc of 45.9 °C. Through in-situ annealing treatment, the Tlum and ΔTsol of VO2(12 nm)/W-VO2(12 nm)/VO2(12 nm) further significantly enhanced to 79.3 % and 9.1 %, and Tc also reduced slightly to 41.4 °C. SEM characterization suggested that the improved optical properties can be attributed to the Localized Surface Plasmon Resonance (LSPR) effect of the spherically structured W-VO2 nanoparticles. The results in this study confirmed that the thermochromic properties of W-VO2 could be optimized by controlling its grain morphology, which provided a new strategy for the application of W-VO2 films in the field of smart windows.

Regulating Crystallinity Mismatch Between Donor and Acceptor to Improve Exciton/Charge Transport in Efficient Organic Solar Cells.

Achieving a more balanced charge transport by morphological control is crucial in reducing bimolecular and trap-assisted recombination and enhancing the critical parameters for efficient organic solar cells (OSCs). Hence, a facile strategy is proposed to reduce the crystallinity difference between donor and acceptor by incorporating a novel multifunctional liquid crystal small molecule (LCSM) BDTPF4-C6 into the binary blend. BDTPF4-C6 is the first LCSM based on a tetrafluorobenzene unit and features a low liquid crystal phase transition temperature and strong self-assembly ability, conducive to regulating the active layer morphology. When BDTPF4-C6 is introduced as a guest molecule into the PM6 : Y6 binary, it exhibits better compatibility with the donor PM6 and primarily resides within the PM6 phase because of the similarity-intermiscibility principle. Moreover, systematic studies revealed that BDTPF4-C6 could be used as a seeding agent for PM6 to enhance its crystallinity, thereby forming a more balanced and favourable charge transport with suppressed charge recombination. Intriguingly, dual Förster resonance energy transfer was observed between the guest molecule and the host donor and acceptor, resulting in an improved current density. This study demonstrates a facile approach to balance the charge mobilities and offers new insights into boosting the efficiency of single-junction OSCs beyond 20 %.

Regulating Crystallinity Mismatch Between Donor and Acceptor to Improve Exciton/Charge Transport in Efficient Organic Solar Cells

AbstractAchieving a more balanced charge transport by morphological control is crucial in reducing bimolecular and trap‐assisted recombination and enhancing the critical parameters for efficient organic solar cells (OSCs). Hence, a facile strategy is proposed to reduce the crystallinity difference between donor and acceptor by incorporating a novel multifunctional liquid crystal small molecule (LCSM) BDTPF4‐C6 into the binary blend. BDTPF4‐C6 is the first LCSM based on a tetrafluorobenzene unit and features a low liquid crystal phase transition temperature and strong self‐assembly ability, conducive to regulating the active layer morphology. When BDTPF4‐C6 is introduced as a guest molecule into the PM6 : Y6 binary, it exhibits better compatibility with the donor PM6 and primarily resides within the PM6 phase because of the similarity‐intermiscibility principle. Moreover, systematic studies revealed that BDTPF4‐C6 could be used as a seeding agent for PM6 to enhance its crystallinity, thereby forming a more balanced and favourable charge transport with suppressed charge recombination. Intriguingly, dual Förster resonance energy transfer was observed between the guest molecule and the host donor and acceptor, resulting in an improved current density. This study demonstrates a facile approach to balance the charge mobilities and offers new insights into boosting the efficiency of single‐junction OSCs beyond 20 %.

Tailoring the Techno-Functional Properties of Fava Bean Protein Isolates: A Comparative Evaluation of Ultrasonication and Pulsed Electric Field Treatments

The fava bean protein isolate (FBPI) holds promise as a sustainable plant-based protein ingredient. However, native FBPIs exhibit limited functionality, including unsuitable emulsifying activities and a low solubility at a neutral pH, restricting their applications. This study is focused on the effect of ultrasonication (US) and pulsed electric fields (PEF) on modulating the techno-functional properties of FBPIs. Native FBPIs were treated with US at amplitudes of 60–90% for 30 min in 0.5 s on-and-off cycles and with PEF at an electric field intensity of 1.5 kV/cm with 1000–4000 pulses of 20 μs pulse widths. US caused a reduction in the size and charge of the FBPIs more prominently than the PEF. Protein characterization by means of SDS-PAGE illustrated that US and PEF caused severe-to-moderate changes in the molecular weight of the FBPIs. In addition, a spectroscopic analysis using Fourier-transform infrared (FTIR) and circular dichroism (CD) revealed that US and the PEF induced conformational changes through partial unfolding and secondary structure remodeling from an α-helix to a β-sheet. Crystallographic and calorimetric determinations indicated decreased crystallinity and lowered thermal transition temperatures of the US- and PEF-modified FBPIs. Overall, non-thermal processing provided an effective strategy for upgrading FBPIs’ functionality, with implications for developing competitive plant-based protein alternatives.

Organic ferroelastic enantiomers with high Tc and large dielectric switching ratio triggered by order-disorder and displacive phase transition

Molecular-based ferroelastics with dielectric switching properties are highly desirable for their applications on microelectronic dielectric switches, sensors, data storage, and so on. However, the current reports mostly focus on organic-inorganic hybrids containing toxic heavy metal atoms, and the relatively low phase transition temperature limits their application. In this paper, low-toxic organic salt ferroelastic enantiomers (R/S)-4-fluoro-1-azabicyclo[3.2.1]octonium chloride [(R/S)-F-321] were designed and synthesized under the introducing chirality strategy. They undergo a 432F422-type ferroelastic phase transition with a high Curie temperature (Tc) of 470 K, simultaneously exhibiting excellent dielectric switching characteristics. In addition to the ordered-disordered movement of cations, the significant displacement of anions is also responsible for such high Tc and large dielectric switching ratios, which is very rare in molecular-based switching materials. This work enriches the development of molecular ferroelastic switching materials and gives inspiration for the exploration of environmentally friendly high Tc organic salt ferroelastics with prominent switching performances.