Abstract As a class of two-dimensional materials, MBenes have attracted increasing interest due to their high electrical conductivity. Using first-principles calculations combined with the Boltzmann transport equation, we investigate the intrinsic charge transport in orthorhombic 5d-based Hf2B2. The room-temperature 2D conductivity reaches 7.41 mS/□, comparable to most known MBenes and MXenes. At 20 K and the high-temperature limit (more than 1500 K), the resistivity follows T3.7 and T1 power laws, respectively. The local exponent n(T) = dln ρ2D/d ln T reveals a two-stage crossover separated by a characteristic temperature TM = 93 K: below TM, n(T) decreases rapidly from 3.7 to about 1.5; above TM, it slowly approaches 1. Our results demonstrate that the rapid decrease originates from the low-frequency phonons below the phonon gap, whereas the slow decrease arises from the additional activation of high-frequency phonons above the phonon gap.
Abstract Zr3C2O2 MXene has garnered extensive interest as an anode material for alkali-ion batteries. Nevertheless, its inferior electrochemical performance compared to the well-established Ti- and V-based MXenes calls for targeted strategies to unlock its full potential. Heteroatom doping with nonmetals offers an effective way to overcome these limitations by tuning the electronic structure and surface chemistry while keeping the MXene framework intact. Herein, first-principles density functional theory calculations are used to systematically investigate nitrogen (N) and sulfur (S) substitution at the carbon site of Zr3C2O2 MXene. The effects of doping on its structural, electronic, and electrochemical properties as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs) are examined. Three doping strategies were considered: N mono-doping, S mono-doping, and N–S co-doping. We evaluate each of these strategies for a range of dopant concentrations from single atom substitution to full site occupation within the supercell. Such a systematic study allows us to probe the isolated defect behavior at low concentrations and the dopant–dopant interaction and collective electronic modulation at higher doping levels. The calculations confirm that substitution at the carbon site is energetically favorable for both heteroatoms. N-doped systems consistently outperform S-doped and N–S co-doped counterparts in terms of structural stability, metallicity, and electrochemical response. N–S co-doping shows synergistic improvements than S doping. The 12N-substituted Zr3C2O2 exhibits the best performance with the highest density of states at the Fermi level, favorable Li/Na adsorption energetics, the lowest average open-circuit voltage, and reduced ion diffusion barriers among all the configurations. Theoretical specific capacities of 328 mA h g–1 for LIBs and 283 mA h g–1 for NIBs are achieved. These findings demonstrate that controlled heteroatom substitution is an effective design strategy for simultaneously optimizing structural integrity, electronic conductivity, energy density, and ion storage capacity in MXene-based anodes for next-generation alkali-ion batteries.
Abstract A central challenge for next-generation intelligent optoelectronic systems is to co-integrate photodetection and neuromorphic in-sensor computing within a single device to eliminate redundant data transfer between physically separated units. Herein, we demonstrate a gate-reconfigurable ZnO/β-Ga2O3 heterojunction phototransistor that reconciles these two antagonistic functions via a bias-switchable carrier-transport pathway. The device design couples (i) a large interfacial conduction-band energetic step and (ii) oxygen-vacancy-related trap states distributed in the Ga2O3 layer, enabling the external gate voltage to toggle the dominant mechanism between rapid electron transfer/collection and Ov-mediated persistent photoconductivity (PPC). In the photodetection mode (VG = +10 V) under 366 nm illumination, the phototransistor exhibits a responsivity of 7.5 × 104 A/W, a shot-noise-limited specific detectivity of 7.8 × 1014 Jones, and an external quantum efficiency of 3.8 × 107%, with a weak optical intensity of 10 μW/cm2. Complementary measurements at 290 nm further confirm the dual-wavelength ultraviolet response of the device. This mode enables optical ASCII communication and intensity-reconfigurable Boolean logic (AND/OR) within a single transistor. In the neuromorphic synapse mode (VG = –10 V), enhanced electron confinement in the oxygen-vacancy-rich Ga2O3 layer activates pronounced PPC, enabling robust emulation of synaptic plasticity including paired-pulse facilitation (PPF), short-term-to-long-term (STP-LTP) plasticity transition, learning-forgetting-relearning, and Pavlovian conditioning under both 290 and 366 nm excitation. Moreover, leveraging PPC as a bio-inspired resource, we extend functionality to artificial nociceptors (hyperalgesia and allodynia) and dual-wavelength spatiotemporal encoding, highlighting a versatile materials/device strategy for integrated neuromorphic vision and programmable optoelectronic computing hardware.
Abstract Realizing the potential of oxide-based memristive devices for high-density data storage and energy-efficient computing still relies on overcoming key technical challenges, including the need for a larger number of stable resistance states, faster switching speeds, lower SET/RESET voltages, improved endurance, and reduced variability. Addressing these limitations requires innovative material design strategies. Here, we demonstrate that introducing a thin layer of oxide-ion conductor SrCoO3–x between the metal and the SrTiO3-based memristive elements, expands the number of distinguishable resistance states from ≈8 to ≈22. This modification also reduced the SET/RESET voltage by 50% and markedly improved device endurance, albeit with a trade-off of reduced state retention. To assess the performance of this architecture, we trained a two-layer fully connected neural network using the experimental SrTiO3/SrCoO3–x memristor characteristics on the MNIST handwritten digit dataset. Networks with hidden-layer sizes between 64 and 256 neurons achieved classification errors below 7%. Finally, we confirmed the transferability of this interface-engineering approach by applying it to HfOx-based devices, achieving a consistent enhancement in the resistive state window.
Abstract Vanadium nitride (VN) is of substantial interest for supercapacitors, owing to its high specific capacitance and high conductivity. Nevertheless, it is hindered by inherent limitations of particle agglomeration, dissolution, and oxidation during the charge/discharge process. To address these challenges, a carbon framework was constructed through thermal treatment of cross-linked polymers between polyacrylamide (PAM) and poly(p-phenylenediamine) (PPPD). Subsequently, a VN/C composite was prepared by in-situ pyrolysis of the polymer gel precursor containing adsorbed V3+ ions under a N2 protective atmosphere. This treatment enabled the in-situ formation of VN anchored to the terminal amino groups along the polymer chains. Furthermore, the effects of VCl3 mass loading (0.15–0.35 g) and temperature (700–900 °C) were studied in the synthetic process. The optimized VN/C composite with a vanadium loading of 0.25 g (denoted VN/C-0.25) sintered at 800 °C delivered a specific capacitance of 251.1 F g–1 at a current density of 0.5 A g–1. Additionally, an asymmetric supercapacitor was assembled using Ni(OH)2 as the positive electrode and VN/C-0.25 as the negative electrode. This device showed a maximum energy density of 26.0 Wh kg–1 at a power density of 511.4 W kg–1, accompanied by outstanding cycling stability over repeated charge–discharge cycles.
Abstract MXenes are an emerging class of pseudocapacitive materials toward developing high-rate energy storage devices. However, irreversible anodic oxidation of MXene limits the voltage window of operation (∼0.6 V) of symmetric devices in aqueous electrolytes. In this study, we demonstrate high-rate operation of MXene symmetric microsupercapacitors (MSCs) in an ionic liquid electrolyte with a voltage window of operation of >2 V. A highly conductive titanium carbide (Ti3C2Tx) MXene thin film is employed as a current collector with ionic liquid premixed small flakes (∼170 nm) of MXene as a charge storage layer. Ti3C2Tx -ionic liquid MSCs operate at high scan rates up to 1000 mV s–1, with typical areal capacitance values in the range of 2–10 mF cm–2. Ti3C2Tx -ionic liquid MSC (thickness, 35 μm) exhibits a maximum device areal capacitance of up to 35 mF cm–2 with an energy density of 30 μWh cm–2 at a power density of 0.3 mW cm–2, that is approximately three times superior to the reported MXene MSC devices.
Abstract Molybdenum disulfide (MoS2), a classic layered transition-metal dichalcogenide (TMD), has emerged as an exceptionally promising candidate for cathode materials in aqueous zinc-ion batteries (AZIBs) due to its distinctive structure that facilitates efficient ion diffusion. However, the practical applications of MoS2 are hindered by challenges relating to its structural stability and electrical conductivity. In this work, a hierarchical wool ball-like structure of the MoS2 nanosphere (MoS2/NSC), incorporating an N,S-doped PVP-derived carbon framework, was successfully fabricated to enhance the structural stability and electrical conductivity of MoS2 materials. The DFT simulation results indicate that MoS2/NSC contributes to a desirable capability of zinc storage. As a cathode material for AZIBs, the battery testing results of MoS2/NSC electrodes demonstrate exceptional cycling performance, maintaining a reversible capacity of 87.5 mA h g−1 at 1.0 A g−1 after 200 cycles with a capacity retention of 93.4%. The remarkable electrochemical performance is attributed to the synergistic effect of the nanosphere architecture resembling wool balls, in conjunction with the N,S-doped PVP-derived carbon framework. This work reveals the promising prospects of the hierarchical MoS2 composites for achieving outstanding results in aqueous zinc-ion storage systems.
Abstract Probabilistic switching in volatile threshold-switching (TS) memristors is often regarded as variability in deterministic circuits, but, when properly calibrated, it can provide a useful probability source for neuromorphic and probabilistic computing. Here, we investigate an Ag/HfO2/Pt/Ti conductive-bridge RAM (CBRAM) device and quantitatively characterize its voltage-dependent switching probability at room temperature within an investigated pulse-amplitude window of 1.6–2.0 V. Structural and chemical analyses confirm the intended device stack, while repeated pulse measurements reveal a stable sigmoid-like switching-probability response, Pswitch (V), within the investigated operating window. The measured response is fitted with a logistic function to establish a device-calibrated probability model. The volatile turn-on and self-reset characteristics are incorporated into a compact leaky-integrate-and-fire (LIF) circuit model, yielding controllable firing dynamics as a function of input amplitude, pulse width, and membrane capacitance. Separately, the calibrated probability function is used as the Bernoulli activation probability for restricted Boltzmann machine (RBM) Gibbs sampling. Under identical training conditions, the device-fitted sigmoid maintains stable learning with a 2.4% accuracy gap relative to the ideal-sigmoid baseline. These results establish an experimentally calibrated measurement-to-model framework that connects volatile TS characteristics to spiking dynamics and probabilistic sampling within the tested operating conditions.
Abstract Conductive hydrogels are attractive substrates for wearable strain sensors because their softness, high water content, and tissue-like compliance enable conformal contact with moving skin. However, simultaneously achieving high deformability, stable electrical transport, and repeatable signal transduction remains challenging. Here, an acrylamide/maleic acid/butyl acrylate copolymer hydrogel containing stevia-derived carbon dots (CDs) and Ti3C2Tx MXene was investigated as a flexible piezoresistive platform. The 10 wt % 2CD:1MXene formulation exhibited the highest measured conductivity, (2.11 ± 0.11) × 10–4 S cm–1, and the lowest Tauc-derived apparent optical transition energy, 2.026 ± 0.013 eV, within the tested formulation range. The optimized hybrid formulation combined enhanced stretchability with a tensile toughness of approximately 41.4 kJ m–3 and maintained an elastic-dominant viscoelastic response, with tanδ values of 0.286 ± 0.008 in the strain sweep and 0.191 ± 0.005 in the frequency sweep at the common comparison condition. The sensor showed gauge factors of 3.088 and recovery times of 8.50 ± 0.48 and 8.63 ± 0.51 s, respectively. After 1000 loading–unloading cycles, 94.57% of the initial response amplitude was retained. On-body measurements demonstrated qualitative detection of joint and physiological motions, while controlled short and long inputs produced distinguishable Morse-code-like temporal patterns. As a wearable strain sensor, the material showed stable and repeatable resistance responses toward finger bending, wrist motion, facial micro-movements, chewing, blinking, and breathing. Importantly, the sensor could translate controlled mechanical inputs into distinguishable Morse-code patterns, enabling the encoding of messages such as “SOS”, “HELP”, and “MXENE”. The resulting hydrogel is, therefore, a promising platform for wearable motion monitoring, soft human-machine interfaces, and Morse-code-assisted communication.
Abstract Hafnia-based ferroelectric tunnel junctions (FTJs) are promising candidates for high-density nonvolatile memory due to their compatibility with CMOS technology. However, their adoption is hindered by low tunneling electroresistance (TER), poor endurance, and sneak currents in high-density array architectures. Here, we report a self-rectifying metal–interlayer–ferroelectric–metal (MIFM) FTJ through simultaneous electrode work-function engineering and the introduction of oxide interlayers to induce asymmetric barrier modulation and serve as oxygen reservoirs for the ferroelectric layer. By systematically comparing InO, IZO, and ZnO interlayers, we confirm ZnO as the optimal interlayer to maximize the barrier asymmetry while suppressing interface defects due to its superior oxygen reservoir (OR) capability, yielding a giant TER ratio of 34,000 and a rectifying ratio (RR) of 1150. Interface analysis reveals a thinner interfacial dead layer, a larger domain size, a 15% lower trap density, and reduced sub-oxide formation in ZnO compared to InO and IZO FTJs, which collectively contribute to superior endurance up to 108 cycles, stable 10 year retention, and low device-to-device variation. Moreover, read margin simulation demonstrates that ZnO-based FTJs support larger crossbar array sizes than InO- and IZO-based FTJs by more effectively suppressing sneak-path currents, highlighting oxide-interlayer engineering as a promising design strategy for improving the reliability and scalability of hafnia-based ferroelectric memory.
Abstract Copper nanowire (CuNW) transparent conductive films (TCFs) are promising flexible transparent electrodes, but their practical application is limited by Cu oxidation and junction degradation under ambient exposure, repeated deformation, and cyclic electrothermal operation. Herein, a room-temperature magnetron sputtering strategy is developed to encapsulate blade-wrapped CuNW networks with an Al-doped ZnO (AZO) overlayer, forming a core–shell architecture composed of crystalline Cu cores and amorphous AZO shells. The thickness-dependent effects of AZO on the microstructure, optoelectronic properties, and durability of the composite films are systematically investigated. AZO encapsulation induces a characteristic optoelectronic trade-off, with decreased transmittance and increased sheet resistance as the AZO thickness increases. Despite this penalty, AZO markedly improves the durability of CuNW TCFs. The 22 nm AZO coating provides the best cyclic electrothermal stability, retaining 99.90% of the initial temperature modulation after 500 on/off cycles, compared with 30.24% for pristine CuNWs. Under cyclic bending (10 mm radius, 5000 cycles), the 31 nm AZO coating shows the lowest ΔR/R0 of 0.09727, compared with 1.09 for pristine CuNWs. AZO-wrapped films also exhibit greatly improved ambient and damp-heat stability. This work provides a scalable, low-thermal-budget route for durable CuNW-based flexible transparent electrodes.
Abstract Quantum dot light-emitting diodes (QLEDs) have attracted considerable attention as next-generation light-emitting devices capable of achieving high emission efficiency based on their organic–inorganic hybrid architecture. However, the environmental degradation and performance loss arising from the vulnerability of the organic layers within the device to oxygen and moisture remain a major factor limiting long-term device stability. To address this issue, we introduce VNPB (N4,N4′-di(naphthalen-1-yl)-N4,N4′-bis(4-vinylphenyl)biphenyl-4,4′-diamine), a cross-linkable hole transport layer (HTL) material, into InP-based QLEDs and systematically investigate the effect of the cross-linking density, controlled by the post-annealing temperature, on the electrical and optical properties of the devices. VNPB contains terminal vinyl groups that enable the formation of an intermolecular covalent network during thermal annealing, thereby providing excellent solvent resistance and structural stability that suppress the re-dissolution of the underlying layer during multilayer solution processing. By varying the post-annealing temperature of the VNPB film from 160 to 190 °C, we elucidated the effect of the cross-linking density on the performance of InP-based QLEDs. Rinsing tests confirmed that the cross-linking density increased progressively with annealing temperature, forming a robust network. Device analysis showed that the 170 °C condition achieved a maximum EQE of 5.55% and the optimal operational lifetime (T70 = 45.1 h). In contrast, devices annealed at 180–190 °C exhibited increased surface roughness and local current response. Together with the larger voltage variation observed under constant-current operation, these results suggest increased morphology-induced localized conduction and electrical instability, resulting in non-uniform charge transport and charge imbalance. This study demonstrates that controlling the cross-linking density of the hole transport layer can serve as an important processing strategy for regulating charge injection balance and recombination behavior in solution-processed QLEDs.
Abstract Gesture recognition based on the Internet of Things and artificial intelligence holds significant importance in human–computer interaction. Different from array-type hydrogel sensors, this research has developed a one-piece flexible hydrogel sensor based on an ion-cross-linked three-dimensional network structure. Through the design of the hydrogel components and its network structure, the Young’s modulus spanning from soft tissues to hard materials has been achieved. The hydrogel exhibits excellent output stability, surface adhesion, and skin adaptability. The test results show that the gesture recognition sensor prepared from this hydrogel has a minimum detection limit of only 0.04% and has excellent cyclic stability. On this basis, combined with the long short-term memory network (LSTM) deep learning algorithm, a complete intelligent gesture recognition system is constructed. This system can precisely recognize complex dynamic gestures and provide real-time feedback while simplifying the hardware connections and data flows. It offers an efficient solution for the field of intelligent care.
Abstract Flexible electrothermal composites that simultaneously achieve mechanical compliance and uniform Joule heating remain a challenge due to the difficulty in uniformly dispersing nanotubes and constructing stable conductive networks within polymer matrices. Here, we present a dispersion-engineered strategy combining sodium dodecyl sulfate (SDS)-assisted stabilization with isopropanol dilution to fabricate multiwalled carbon nanotube/polydimethylsiloxane (MWCNTs/PDMS) composites with a continuous and robust conductive network. The optimized system exhibits a zeta potential shift from −25 mV (SDS-free) to −41 mV, reflecting improved electrostatic stabilization at the nanotube interface. At 5 wt % MWCNT loading, the composite achieves an electrical conductivity of 21.3 S/m, excellent mechanical compliance (Young’s modulus < 0.6 MPa, stretchability > 200%), and remarkable electromechanical stability (2.2% resistance variation after 2000 cycles at 50% strain). The composite delivers stable and uniform Joule heating (∼46.5 °C at 14 V, temperature fluctuation <±1 °C), providing a solid foundation for practical applications. Demonstrated in wearable wax therapy, the composite enables conformal skin contact and reliable thermal performance, with high mechanical compliance of 50%, an insulation time of 2 h, which is superior to the other four commercial products. This work establishes a generalizable dispersion engineering approach for uniform electrothermal composites, offering a promising platform for uniform thermal management (±1 °C) and long-term rehabilitative therapy (120 min).
Abstract Wireless optical communication operating in the ultraviolet band has received widespread attention due to its secure data transmission and solar-blind characteristics. However, the performance of conventional transmitters is restricted by interconnect parasitic circuit effects, and incorporating InGaN within any epitaxial layer inevitably provokes severe lattice mismatches and subsequent crystalline degradation. Building upon our experimental development of high-performance standalone MOS-HEMTs and InGaN UV-LEDs, this work explores a monolithically integrated device constructed entirely utilizing the AlGaN/GaN system to circumvent these electrical and material bottlenecks. Rigorous TCAD simulations reveal that incorporating a recessed-gate MOS-HEMT with an Al2O3 dielectric layer successfully blocks vertical electron tunneling and resolves the current collapse observed in Schottky gate designs. The device exhibits an on-resistance of 22.51 Ω·mm and a stable maximum drain current density exceeding 400 mA/mm delivered to the series optical emitter. Benefiting from the engineered dielectric isolation, the integrated device achieved a cutoff frequency of 656 MHz and a maximum oscillation frequency of 495 MHz. More interestingly, we found that under large-signal modulation, the device maintains synchronized electro-optical tracking up to 50 MHz, preserving over 90% of the initial amplitude swing. These dynamic evaluations correspond to an electrical current stabilization within 5 ns and a roughly estimated optical modulation bandwidth of 16 MHz. Ultimately, we demonstrate a robust monolithic integration strategy for UV optical transmitters, providing a theoretical foundation for next-generation wireless communication systems.
Abstract Flexible electronics, textile engineering, and nanomaterials have combined to transform gas sensing from rigid devices into advanced wearable platforms. The most recent developments in flexible substrate-integrated gas sensor components are examined in this review, with particular attention paid to their ability to detect hydrogen (H2), nitrogen dioxide (NO2), and ammonia (NH3). Protonation-driven charge transfer for selective NH3 detection; catalytic lattice modulation via palladium hydride formation, which regulates H2 sensing via percolation dynamics; and adsorption-induced band modulation for NO2 detection based on oxidative electron withdrawal and engineered heterointerfaces are the three distinct methods of gas sensing. Furthermore, mesoporous diffusion paths, heterojunction-based signal amplification, defect-engineered nanostructures, and mechanically robust conductive networks all contribute to the improved performance of these systems. This work integrates textile compatibility, structural design, and gas material interaction chemistry to give a unified framework for the logical development of wearable sensing platforms with many functions. Cross-selectivity, humidity sensitivity, long-term mechanical durability, and scalable production are some of the major issues that still need to be resolved despite significant advancements in room temperature operation and mechanical flexibility. The integration of IoT-enabled data analytics, machine learning to aid in signal classification, and self-powered sensing devices will probably be the main focus in the future. With the goal to assist users to develop scalable, intelligent, and self-monitoring textile-based gas sensing networks, this paper integrates all the opportunities and issues into a single platform.
Abstract Efficient polymer-based microwave absorbers require incident waves to enter the material and then be sufficiently attenuated inside the absorber. This balance is difficult to achieve when design relies only on high dielectric loss. Here, Co−Fe/epoxy (Co−Fe/EP) composites are used as a dual-magnetic model platform in which the Co/Fe ratio regulates magnetic storage, magnetic loss, interfacial polarization, and input impedance while the epoxy matrix maintains a moderate dielectric response. The optimized composites exhibit an effective absorption bandwidth of up to 6.42 GHz and a minimum reflection loss of −54.04 dB at millimeter-scale thicknesses. A numerical magnetic-parameter reconstruction and sensitivity-analysis framework is established using the measured permittivity and reconstructed permeability. The reconstructed response agrees closely with the measured-parameter result, giving an RL root-mean-square error of 0.286 dB. Removing the magnetic response or setting μ″ to zero eliminates the effective absorption region, whereas independent tuning shows that μ″ mainly regulates attenuation intensity and μ′ controls peak migration and the input-impedance trajectory. Area-based analysis further demonstrates that effective broadband absorption is associated with the overlap of impedance-matching and attenuation regions rather than with the maximum of any single loss parameter. Density functional theory calculations support Co−Fe interfacial d-orbital coupling and localized charge redistribution as microscopic origins of interfacial polarization. These results establish a reproducible magnetic-response-regulated framework for balancing wave accessibility and internal attenuation in epoxy-based absorbers.
Abstract The global energy crisis, along with the accumulation of plastic waste (PW), has increased the upcycling of PW for energy storage. Here, we synthesize and investigate the supercapacitance (SC) properties of a waste polyethylene terephthalate-derived porous activated carbon-MoS2 composite via a one-pot hydrothermal method (HT-W-PET-AC-MoS2) and by physical mixing (PM-W-PET-AC + MoS2). The HT composite with 80 wt % MoS2 exhibits the highest specific capacitance (Csp) of 445 and 272 F g–1 at 0.50 and 1 A g–1, whereas W-PET-AC, MoS2, and the PM-analogue deliver 188, 190, and 295 F g–1 at 0.50 A g–1. Trasatti’s analysis reveals 93% electrochemical double-layer capacitor (EDLC) contribution for the PM and 47% pseudocapacitance (Cpseudo) and 53% EDLC in HT. The enhancement in the Csp value (51% increase) of HT compared to PM is attributed to additional conductivity by electron transfer via chemical bonds between W-PET-AC and MoS2, activating the Cpseudo of MoS2. Conversely, the cyclic stability showed that the PM composite exhibited 100% capacitance retention, whereas HT showed only 63% over 5000 cycles. Thus, this study provides clear evidence that the pseudobehavior of MoS2 in the HT-W-PET-AC-MoS280 composite is enriched through bond formation and emphasizes the role of molecular-level electron transfer in activating pseudobehavior in the HT composite, while the PM composite exhibited lower Csp and higher cyclic stability, indicating EDLC dominance. Further, a two-electrode symmetric coin cell device is fabricated for HT and PM, which delivers an energy density (Ed) of 23.20 Wh kg–1 and a power density (Pd) of 4896 W kg–1 for HT and 12.10 Wh kg–1 and 4800 W kg–1 for PM.
Abstract Halide perovskite quantum dots (PeQDs) have emerged as compelling emissive materials for next-generation displays owing to their narrow emission linewidths and high photoluminescence quantum yields (PLQYs). However, their limited environmental stability and the requirement for strictly controlled inert atmospheres during fabrication remain significant barriers to practical deployment. In this study, we present the scalable fabrication of green-emitting perovskite quantum-dot light-emitting diodes (PeQD-LEDs) via electrohydrodynamic (EHD) jet printing performed entirely under ambient air conditions. A carefully engineered halogen-free binary solvent ink—consisting of decalin and n-tridecane at a 7:3 volume ratio—was employed to suppress coffee-ring formation through an inward Marangoni flow, ensuring stable jetting behavior. Notably, the EHD-printed devices exhibited performance metrics highly comparable to conventional spin-coated reference devices. While the EHD-printed PeQD-LEDs showed a slight shift toward a higher turn-on voltage and a lower current density due to the increased thickness of the printed emissive layer, the peak luminance and efficiency values remained largely consistent. Specifically, the air-processed EHD devices achieved a maximum luminance exceeding 11,600 cd/m2 and a peak current efficiency (CE) of approximately 5.0 cd/A, proving that our ink−interface codesign effectively facilitates comparable carrier injection. The successful demonstration of uniform PeQD-LEDs under ambient air points toward the possibility of a robust and industrially relevant manufacturing route for high-resolution displays without the need for an expensive inert-gas infrastructure.
Abstract We demonstrate a metastable fingerprint (mFP) state in a homeotropically aligned cholesteric liquid crystal (CLC) with negative dielectric anisotropy. The mFP forms upon gradual removal of a high-voltage, low-frequency electric field and persists for several hours at zero field. Factors influencing the stability of this state include the confinement ratio—the ratio of the cell thickness to the cholesteric pitch, ρ = d/p—the alignment layer rubbing strength, and material composition. Electro-optical characterization of the dichroic dye-doped CLC in a single-layer cell reveals four distinct optical states: a clear state, two tinted states, and a hazy state. Furthermore, CTAB-doping enables controlled erasure of the mFP and access to bubble domains, a distinct, weakly scattering, tinted state. In the optimized configuration (ρ ≈ 1, five-times rubbed alignment layer), driving at 80 mV s–1, the induced mFP persists for 400–500 min when the voltage is removed. These findings establish mFP textures as a promising route for developing bistable cholesteric optical devices such as liquid crystal windows.
