Abstract This study utilizes a metalorganic chemical vapor deposition system to grow a β‐Ga2O3 epitaxial layer on a sapphire substrate and fabricate lateral β‐Ga2O3 metal‐oxide‐semiconductor field‐effect transistors (MOSFETs). To enhance the performance of the β‐Ga2O3 MOSFET, a (AlxGa1‐x)2O3 spacer layer is introduced, with its aluminum (Al) composition modulated through energy band engineering. Three epitaxial samples are designed: a reference sample (without a spacer layer) and samples with (AlxGa1‐x)2O3 layers containing different Al compositions, specifically (Al0.14Ga0.86)2O3 and (Al0.21Ga0.79)2O3. The influence of the Al composition in the (AlxGa1‐x)2O3 layer on the two dimensional electron gas (2DEG) is investigated. The results show that a lower Al composition increases the carrier concentration in the 2DEG, boosting the saturation current (ID,sat) from 2.94 to 7.88 mA mm−1—a significant 168% improvement in the (AlxGa1‐x)2O3/β‐Ga2O3 stacked epitaxy structure. For the high‐Al‐composition barrier layer ((Al0.21Ga0.79)2O3), the higher energy barrier slightly reduces the turn‐on current but effectively increases the breakdown voltage, from 210 to 576 V—an improvement of 188%. These improvements result from the higher energy barrier of the β‐Ga2O3/(AlxGa1‐x)2O3 interface, which reduced the leakage current density. By optimizing the Al composition in (AlxGa1‐x)2O3, transistors suitable for either high performance or high breakdown voltage are successfully produced.

Abstract Chemical oscillators—such as the Belousov‐Zhabotinsky reaction—have long served as model systems for studying non‐equilibrium chemical dynamics and as analogues of biological oscillations. However, many biological processes rely on out‐of‐equilibrium, often oscillatory, ionic fluxes that do not involve chemical reactions. Examples include action potentials in neurons, muscle contraction, cardiac rhythmicity, intracellular calcium signaling, and calcium wave oscillations. Despite these parallels, the development of biomimetic systems compatible with neuromorphic interfaces remains a significant challenge. Here, a strategy is demonstrated to organize oscillating ionic currents by developing ionic transistors composed of graphene oxide and polyelectrolyte, and assembling them into all‐ionic integrated circuits. By driving these systems out of equilibrium using external voltages, periodic motion of various ions across defined interfaces is achieved. This behavior, governed by local electric fields arising from unbalanced ionic concentrations, closely mimics biological excitability, such as that observed in neuronal and cardiac systems. These ionic transistors serve as a foundational building block for neuromorphic interfaces, offering a universal platform to emulate complex biological ionic processes with high fidelity.

Abstract Transparent organic photodetectors are promising for applications in wearable and communication electronics, where they can serve as imperceptible sensors. Yet, common fabrication techniques such as spin coating and evaporation have limited compatibility with high‐throughput production and scalability. In this work, semi‐transparent and opaque organic photodiodes, inkjet‐printed on indium tin oxide electrodes, reaching a transmittance of up to 70.6% in the visible range are demonstrated. The diode's active layer comprises a transparent donor polymer and Y7 as a non‐fullerene acceptor. This bulk heterojunction results in near‐infrared responsivity with maximum values of 12 ± 2 mA W−1 at −2 V and 840 nm for semi‐transparent diodes with Poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate electrodes and 60 ± 7 mA W−1 for opaque devices with Ag electrodes. The diodes exhibit high detection speeds of up to 3 MHz, making them suitable for near‐infrared communication systems for soft robotics as well as wearable health monitoring, as demonstrated by pulse plethysmography.

Abstract Doping allows precise tuning of the electronic properties in 2D materials, optimizing their performance for applications such as complementary metal‐oxide‐semiconductor (CMOS) technology. However, developing reliable p‐type 2D semiconductors remains challenging due to intrinsic defects or unintentional n‐type doping. This study presents robust p‐type monolayer WSe2 field‐effect transistors (FETs) using phase‐engineered WSe2/WSeyOx building blocks created via an atomic oxidation process (AOP). The findings reveal that when bilayer WSe2 is exposed to AOP, the top layer undergoes self‐limited oxidation to WSeyOx with no detectable oxidation of the bottom layer. This result is confirmed by Raman spectroscopy, X‐ray photoelectron spectroscopy, and Kelvin probe force microscopy. This process has further been used to demonstrate a well‐controlled and fully encapsulated WSeyOx/WSe2/WSeyOx heterostructure, ensuring symmetrical protection and stability of the WSe2 channel region. The surface charge transfer doping using WSeyOx provides the capability to selectively modulate the carrier concentration in a WSe2 without altering the intrinsic properties of the channel. This non‐destructive method simplifies the fabrication of p‐type 2D FETs with monolithic, phase‐engineered heterostructures, facilitating seamless integration into next‐generation device architectures.

Abstract The realization of artificial neural circuits requires synaptic materials and devices that show adaptation at different time scales to modulate signal transmission between neurons according to the desired applications. Sensory‐motor and intelligence operation in the brain relies on the dynamical properties of synapses that adapt to the frequency and synchronization of voltage spikes. The properties of potentiation and depression of the synapse conductivity control the plasticity and adaptation of synapses. Here, the general dynamical properties of ionic or electronic current conduction that form the main rules of synaptic activity are discussed. The basic model requirements of a memristor or chemical inductor to produce an adaptation of conductance to incoming stimuli are established. The synaptic response can be described by the combination of three factors: A conduction process that depends on an internal state variable x; this variable causes rectification at an onset voltage; it also causes a memory, characterized by a delay in response to the stimulus. Diverse diagnosis methods are described that connect the nonlinear time response, the nonlinear cycling of current–voltage curves, and the linear frequency response of impedance spectroscopy, to assess the adaptation properties.

Abstract Tandem quantum‐dot light‐emitting diodes (QLEDs) have attracted considerable attention in optoelectronics due to their potential for high efficiency and stability in display applications. A critical component in these devices is the charge‐generating layer (CGL), which commonly employs PEDOT:PSS for its hole injection properties and compatibility with solution processing, despite limitations related to acidity and orthogonal solubility. Phosphomolybdic acid (PMA) has emerged as a promising alternative, but its practical application is hindered by inherent oxidation and low work function. In this work, a dipole‐engineered CGL is reported by chemically anchoring ammonium acetate (AMA) layers at the charge generation interface between PMA and the hole‐transporting layer. AMA incorporation effectively suppresses PMA oxidation, enhances work function, and improves energy‐level alignment, which favors efficient charge separation within the CGLs. Furthermore, the AMA‐coated PMA surface exhibits strong resistance to solvent damage during subsequent solution processing. As a result, fully solution‐processed tandem QLEDs with AMA‐modified CGLs achieve a 200% improvement in electroluminescent efficiency compared to single‐emissive‐layer devices. This substantial efficiency improvement highlights the potential of dipole engineering in CGL design and offers valuable insights for developing high‐efficiency optoelectronic devices.

Abstract Low‐frequency electromagnetic (EM) waves are essential in underwater, deep‐earth, and other communication environments due to their minimal attenuation. The magnetoelectric (ME) antenna, a novel mechanical antenna, provides a promising solution for low‐frequency EM wave communication, overcoming the limitations of conventional designs in terms of size and efficiency. To address the low transmission rate in low‐frequency EM wave communication, this paper proposes a multi‐key tunable antenna array based on an ME cantilever beam design. Each antenna array element consists of Metglas/0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN‐PT) ME composite. Simulations identified a structure that significantly lowers the resonant frequency, allowing the ME antenna array to operate within the ultra‐low frequency (ULF, 300 Hz‐3000 Hz) band. Furthermore, the resonant frequency can be tuned over a range of 500 Hz, enabling multi‐frequency‐shift keying (MFSK) communication. Using quaternary FSK (4FSK) modulation, a 40 baud color image transmission is successfully demonstrated in a 5 S m−1 saline environment. Compared to binary FSK (2FSK) at the same baud rate, the transmission speed is increased by 100%. This approach achieves both low attenuation and high transmission rates, offering a promising new direction for ocean communications.

Abstract In this paper, the quasi‐2D green perovskite BA2Cs4Pb5Br16 film passivated by the CH3O‐PEABr is reported to realize nonradiative defect suppressing. The passivated BA2Cs4Pb5Br16 film has a large exciton binding energy (74.9 meV), which is conducive to efficient radiation recombination. Time‐resolved photoluminescence and ultrafast transient absorption spectroscopy show that the carrier lifetime is effectively prolonged after CH3O‐PEABr passivation, indicating photoluminescence enhancement is attributed to the nonradiative defect suppressing. Finally, an electroluminescent green light‐emitting diodes device is fabricated based on the CH3O‐PEABr‐passivated BA2Cs4Pb5Br16 thin film, the maximum external quantum efficiency can be 19.47%. The results indicate that the CH3O‐PEABr passivated BA2Cs4Pb5Br16 thin film can be a promising material for the high‐performance green light‐emitting diodes.

Abstract Space missions critically rely on sensors that operate throughout the near‐ to longwave infrared (NIR – LWIR, λ = 0.9–14 µm) regions of the electromagnetic spectrum. These sensors capture data beyond the capabilities of traditional optical tools and sensors, critical for the detection of thermal emissions, conducting atmospheric studies, and surveillance. However, conventional NIR‐LWIR detectors depend on bulky, cryogenically cooled semiconductors, making them impractical for broader space‐based applications due to their high cost, size, weight, and power (C‐SWaP) demands. Here, an IR photodetector using a solution‐processed narrow bandgap conjugated polymer is demonstrated. This direct bandgap photoconductor demonstrates exceptional infrared sensitivity without cooling and has minimal changes in figures‐of‐merit after substantial ionizing radiation exposure up to 1,000 krad – equivalent to three years in the most intense low Earth orbit (LEO). Its performance and resilience to radiation notably surpass conventional inorganic detectors, with a 7.7 and 98‐fold increase in radiation hardness when compared to epitaxial mercury cadmium telluride (HgCdTe) and indium gallium arsenide (InGaAs) photodiodes, respectively, offering a more affordable, compact, and energy‐efficient alternative. This class of organic semiconductors provides a new frontier for C‐SWaP optimized IR space sensing technologies, enabling the development of new spacecraft and missions with enhanced observational capabilities.