Electrochemical metallization (ECM)-based organic memristors typically rely on an electroforming step to initiate conductive filament (CF) growth; however, this process is often prolonged and unreliable due to uncontrolled ion migration. Despite considerable efforts, achieving stable and reliable organic ECM devices through a simple, solution-process-compatible method remains challenging. Here, we introduce a bilayer organic memristor architecture that confines ion-migration pathways, in which a micelle-engineered transport layer (PT) is integrated with a crosslinked confinement layer (PG). A bilayer organic memristor integrates micelle-engineered PT and crosslinked PG layers to guide vertical Ag+ ion migration and confine filament growth, suppressing the electroforming requirement. The resulting device exhibits low-voltage operation (similar to 0.5 V), a high on/off ratio (similar to 105), and stable data retention exceeding 3600 s. Moreover, crossbar array implementation demonstrates strong potential for neuromorphic computing and large-scale integration, where reproducibility and energy efficiency are critical. Owing to their solution-processable and polymer-based nature, these devices are also well suited for low-cost, flexible, and wearable electronic systems.

Organic electrochemical transistors (OECTs) and electrolyte-gated organic field-effect transistors (EGOFETs) represent promising technologies for neuromorphic computing. Yet, conventional dual-mode devices suffer from fundamental performance trade-offs, where optimization for one mode compromises the other. The primary challenge stems from incompatible interfacial requirements: EGOFETs require stable polarization layers preventing ion penetration, while OECTs demand efficient ionic transport for volumetric doping. Here, we present a novel materials engineering strategy employing zwitterionic-modified poly(methyl methacrylate) (PMMA-ZI) as an interlayer to address this fundamental incompatibility. The amphiphilic zwitterionic moieties simultaneously enhance dipolar polarization for EGOFET operation and facilitate balanced ion transport for OECT functionality through controlled electrostatic interactions. PMMA-ZI devices demonstrate remarkable performance enhancements, with a 13.57-fold improvement in the volumetric capacitance-mobility product to 57.25 F cm-1 V-1 s-1 in OECT mode, compared to conventional PMMA interlayers. The devices exhibit exceptional synaptic plasticity with 6.12 times improved memory retention and successful implementation of 4-bit reservoir computing for pattern recognition. This work establishes a new paradigm for dual-mode organic transistors, enabling uncompromised multifunctional operation essential for next-generation neuromorphic computing and bioelectronics applications.

While organic semiconductors (OSCs) offer potential for next-generation electronics, n-type doping in solution-processed OSCs consistently lags behind p-type doping in efficiency, stability, and reproducibility. A fundamental limitation is the lack of a comprehensive understanding of specific molecular interactions between OSCs and dopants at the structural level. This study addresses this challenge by investigating leuco-Rhodamine B (leuco-RhoB) as an n-type dopant for two polymer OSCs of DPP-DTT and N2200. Combining experimental methods with density functional theory calculations, we elucidate the molecular interactions governing OSC-dopant binding preferences and their impact on electrical performance. Spatial overlap between the van der Waals volumes of the OSCs and leuco-RhoB correlates with binding energy, with N2200 exhibiting stronger binding than DPP-DTT. This enhanced interaction is consistent with improved spatial complementarity, contributing to the improved doping efficiency observed in N2200. Atomic force microscopy and x-ray diffraction analyses confirm better miscibility of leuco-RhoB with N2200, while electrical characterization demonstrates typical n-type doping effects. Leuco-RhoB-doped OSCs exhibit enhanced photoresponsive behavior with improved responsivity, external quantum efficiency, and detectivity, along with faster response times of 0.08 s. These findings advance the rational design of n-type dopants by highlighting the importance of specific structural interactions with OSC beyond energy level alignment.

Aligned polymer nanowires in organic transistors achieve highly linear synaptic plasticity by enhancing interactions between conjugated polymer and ion–gel electrolytes, enabling efficient neuromorphic computing.

Abstract Neuromorphic sensing technology is rapidly evolving from laboratory demonstrations to application‐driven prototypes such as multimodal wearables that integrate touch, vision, and chemistry, synaptic devices operating under aqueous, low‐voltage conditions, and skin‐like arrays capable of on‐site learning. Organic materials have emerged as promising candidates for these technologies owing to their softness, biocompatibility, and intrinsic ionic–electronic coupling that emulates synaptic signaling. Despite accelerating progress in wearables and human–machine interfaces, this field still lacks an integrated, application‐oriented overview of organic neuromorphic systems. This review addresses that gap by clarifying when to employ different device platforms and how electric signals are translated into chemical, physical, and visual sensing. We first discuss the characteristics of bioneural signals and how the devices can mimic them. We then compare device platforms, including two‐terminal devices and three‐terminal transistors, outlining their structures and operation mechanisms. Building on these foundations, we introduce various sensory applications across chemical detection, physical stimuli, and visual photoreception, including multimodal architectures that integrate heterogeneous inputs within a single adaptive system. The review concludes by summarizing the defining characteristics of organic neuromorphic devices and outlining the remaining challenges for future research.

Organic electrochemical transistors (OECTs) gain significant attention due to their low-voltage operation, high transconductance, and biocompatibility. However, conventional OECTs face a fundamental challenge in photosensing applications: severely compromised photoresponse caused by light scattering at the electrolyte-semiconductor interface, where the stacked configuration gives optical losses through reflection, refraction, and scattering. Here, a highly light-responsive detachable photosensor featuring an integrated semiconductor-electrolyte layer configuration is developed. Our approach eliminates light scattering interfaces by introducing a π-ion film/mesh structure based on DPP-DTT conjugated polymer integrated with BMIM:TFSI ionic liquid, creating a seamless mixed ionic-electronic conductor that allows direct light access to photoactive materials. This architecture demonstrates dramatically superior optoelectronic performance compared to conventional DPP-DTT film OECTs. The π-ion film/mesh device achieved 2.78 times enhancement in responsivity of 3.98 × 102 A W1-, 23.7 times improvement in photocurrent ratio of 9.04 × 101, and 1.46 times improved specific detectivity. The detachable design enables practical reusability, maintaining stable performance through approximately 100 electrical cycles and 4 mechanical detach/attach operations. The detachable π-ion film/mesh photosensor technology establishes design principles for next-generation organic optoelectronic devices, offering practical advantages for sustainable, high-performance sensor applications.

PEDOT:PSS is a versatile conducting polymer renowned for high conductivity, flexibility, environmental stability, and biocompatibility, making it ideal for wearable organic transistors. Conventional PEDOT:PSS-based organic electrochemical transistors (OECTs) are limited to depletion mode operation, hindering their potential for advanced neuromorphic systems and complementary circuit designs. This study introduces a novel approach using graphene oxide (GO) coating on PEDOT:PSS microfibers (PMFs) fabricated via wet-spinning sol–gel method to enable accumulation mode operation. The GO modification, enriched with oxygen-containing functional groups (–OH, –COOH, and –O–), introduces ion trap states and enhances ionic-electronic coupling through negatively charged surface modulation. Optimal GO concentration (5 mg mL⁻1) achieved μC* of 631.40 F cm⁻1 V⁻1 s⁻1 in accumulation mode with Ion/Ioff of 50.90, significantly outperforming pristine PMF OECTs. The devices demonstrated exceptional mechanical durability, maintaining structural integrity after 1500 bending cycles with minimal resistance change. Moreover, GO-coated PMF OECTs exhibited remarkable synaptic properties including enhanced paired-pulse facilitation (136

Detecting near-infrared (NIR) light in neuromorphic devices enables advanced sensory processing and expands functionality for bio-inspired vision systems. However, Conventional organic neuromorphic devices exhibit limitations in charge trapping and exciton dissociation under NIR illumination, limiting synaptic performance. To address these limitations, photoneuromorphic organic field-effect transistor (pOFET) incorporating a PVDF-HFP/quantum dot (QD)-based dielectric layer is developed. PVDF-HFP of ferroelectric dielectric enhances charge retention and exciton dissociation, while CdSe/CdS QDs improve light absorption and charge transfer efficiency. The pOFET demonstrates outstanding photoresponsivity of 191.45 A W-1 and external quantum efficiency of 2.74 & times; 104% under NIR illumination, with detectivity reaching 2.50 & times; 1013 Jones. Compared to pristine TIPS-pentacene devices, pOFETs show an increased excitatory post-synaptic current baseline of 15.50 times enhancements under NIR illumination. Long-term memory characteristics of 47.19% with PVDF-HFP incorporation are achieved compared to 8.11% without PVDF-HFP. The pOFETs successfully demonstrate neuromorphic computing capabilities including Pavlovian associative learning and reservoir computing across wavelengths. This advancement highlights the critical role of PVDF-HFP in extending the photocurrent response and enhancing synaptic performance. The QDs and PVDF-HFP optimize light absorption and exciton dissociation, enabling efficient optical synapses with neuromorphic computing potential for adaptive color recognition and classification in artificial vision applications.

Neuromorphic devices that emulate biological synaptic behavior are emerging as key enablers for in-sensor intelligence. While visible-light-responsive systems have dominated the field, recent efforts have expanded toward invisible spectral regions: ultraviolet (UV), infrared (IR), and X-ray, where unique photon-matter interactions offer new avenues for optical plasticity. These invisible-wavelength stimuli enable synaptic functions such as short-term and long-term potentiation through mechanisms like persistent photoconductivity, defect ionization, and interfacial charge trapping, often without the need for external programming circuitry. Although these devices are increasingly important for intelligent imaging, radiation-tolerant electronics, and secure communication, related studies are still fragmented across different fields and lack an organized overview. In this review, we systematically categorize and analyze optoelectronic synapses that operate under UV, IR, and X-ray illumination. We highlight representative material systems including Ga2O3, perovskites, wide-bandgap oxides, and hybrid nanocomposites, and discuss their device architectures, synaptic behaviors, and operational metrics. Special emphasis is placed on the underlying physical mechanisms, spectral selectivity, and integration prospects for artificial retinas, neuromorphic vision systems, and multimodal sensing arrays. We also provide outlooks for scalable, multispectral, and energy-efficient neuromorphic platforms beyond the visible.

Organic source-gated transistors (OSGTs) offer promising advantages for low-power electronics, including high on/off current ratios and reduced saturation drain voltages. However, high Schottky barriers at source electrodes limit their performance, resulting in lower apparent charge carrier mobility, reduced on-current, and elevated threshold voltages compared to conventional organic field-effect transistors (OFETs). Here, a modified source electrode architecture that addresses these fundamental limitations of OSGTs through strategic integration of Schottky and Ohmic contact regions is presented. By reducing the Schottky contact length from 600 to 240 & micro;m and inserting Ohmic Ag contacts, a thinner depletion envelope while maintaining barrier functionality is created. The modified OSGTs demonstrate performance enhancements: mobility increases nearly tenfold from 2.92 & times; 10(-3) to 1.99 & times; 10(-2) cm(2) V-1 s(-1), approaching OFET levels, while threshold voltage decreases from 35.31 to 20.44 V. Moreover, modified OSGTs exhibit exceptional thermal stability with an activation energy of only 0.021 eV, substantially lower than 0.097 eV in OFETs, enabling temperature-independent charge transport through suppression of hopping conduction. Technology computer-aided design simulations validate enhanced conductivity and charge density distribution. This electrode engineering strategy offers a viable pathway toward stable, low-voltage organic electronics with potential applications in flexible and wearable devices.

Abstract Organic electrochemical transistors (OECTs) represent a promising platform for ion sensing applications due to their unique volumetric doping mechanism and biocompatibility. However, achieving enhanced cation detection while maintaining scalable and cost-effective fabrication remains a significant challenge, limiting their practical deployment. Here, an all-solution approach that integrates ion-responsive polymer coatings on silver gate electrodes to address both sensitivity and manufacturability concerns is presented. Our fabrication strategy employs screen-printing techniques exclusively on flexible polyethylene terephthalate substrates, utilizing cross-linked poly(3-hexylthiophene) channels and strategically modified gate electrodes with Nafion or chitosan coatings. Nafion-coated devices demonstrate superior performance with twice transconductance enhancement from 3.2 to 6.6 mS and dramatically reduce charge-transfer resistance from 30 to 2.3 kΩ, enabling enhanced cation response across 10–5 to 1 M concentrations while maintaining excellent resistance to neutral organic interferents. Chitosan-modified electrodes achieve the fastest temporal response with 3 times faster recovery times. The devices exhibit robust reproducibility and stability, with negligible interference from common neutral organic solvents including ethanol, acetone, and hexane. This scalable platform opens possibilities for industrial-scale production of disposable biosensors, particularly for point-of-care medical diagnostics and environmental monitoring applications requiring cost-effective, high-performance ion detection.

Physically unclonable functions (PUFs) provide device-level randomness for secure hardware applications. Here we report a Bi2S3 thin-film PUF based on mixed self-assembled monolayer (SAM) doping. Phenyltrichlorosilane (PTS) and octadecyltrichlorosilane (ODTS) were co-deposited to introduce interfacial dipole variations on the bismuth sulfide (Bi2S3) surface. The resulting polarity disorder modulates charge injection barriers and generates random conductivity across two-terminal devices. Structural and surface analyses, including XPS, contact angle, and Kelvin probe force microscopy, offer the coexistence of distinct SAM dipoles and their effect on work function distribution. The mixed SAM-doped PUF exhibits uniformity (similar to 51.5%), inter-Hamming distance (similar to 43.42%), and entropy (similar to 0.94). Using these random responses, we demonstrate pixel-level image encryption that can only be decrypted with the same device. This approach highlights interfacial dipole engineering as an effective route to stable and unclonable hardware security.

Conventional photo-synaptic devices show two major limitations of the short duration of long-term memory (LTM) due to the lack of effective trap layers and the poor synaptic performance in near-infrared (NIR) photostimulation of low spectral energy. To overcome these challenges, this study develops NIR photonic synaptic organic field-effect transistors (OFETs) incorporating IEICO-4F as a photosensitizer and PVDF-HFP as a chargetrapping layer. The PVDF-HFP/DPP-DTT/IEICO-4F OFETs exhibit outstanding optoelectronic properties compared to pristine DPP-DTT OFETs, with photo-to-dark current ratio dramatically improving from 3.06 & times; 10_ 1 to 8.27 & times; 103 and detectivity of 1.08 & times; 1015 Jones under NIR illumination. Most significantly, the PVDF-HFP trap layer enhances memory characteristics with LTM retention improving from 5.16% to 67.2% even after 1000 s. The devices successfully demonstrate biological synapse-like behavior with paired-pulse facilitation of 280% at 200 ms intervals. The potential of the devices is validated through unimodal associative learning and reservoir computing applications. These advancements suggest NIR photo-synaptic OFETs as promising potential components for next-generation artificial intelligence (AI) hardware and wearable technologies.

Organic electrochemical transistors (OECTs) have attracted significant attention as devices for emulating brain-like information processing. However, their practical implementation is hindered by the limited ion modulation diversity at the active layer-electrolyte interface. To overcome this limitation, we introduce a metal-organic framework (MOF) as a selective ion-conducting layer to modulate ion-pair dissociation. The MOF layer is based on benzoic acid-modified MIL-125-NH2 (BA-MOF), which provides active sites that promote the efficient incorporation of ionic liquid ([EMIM][TFSI]) through intentional defect sites. The defective, highly porous architecture of BA-MOF possesses open-metal sites to tightly bound the ionic liquid. This integration suppresses ion diffusion through BA-MOF, enhancing mobility and overall OECT performance. The effectiveness of this strategy is further demonstrated by MNIST pattern recognition simulations, achieving a maximum accuracy of 94.72%, which is close to the ideal benchmark of 95.22%. This observation is supported by density functional theory (DFT) calculations, which revealed that the confinement of [EMIM][TFSI] ion pairs within BA-MOF reduces the ion-pair dissociation energy, thereby leading to an increased concentration of free anions. These findings highlight that defect-sites of MOF not only facilitate ionic-liquid dissociation but also enable and stable synaptic responses, providing a promising strategy for high-performance brain-inspired organic computing.

Accurate detection of ethanol vapor, a representative volatile organic compound (VOC), is of critical importance for environmental safety, industrial hygiene and healthcare diagnostics. In this study, we present an enzyme-doped gelatin-based organic electrochemical transistor (OECT) that enables real-time ethanol-responsive sensing through enzyme-mediated adaptive signal modulation. The sensor design features a bioinspired gelatin bilayer integrated onto the gate electrode of a PEDOT:PSS OECT. The top gelatin layer (Gelatin B) is functionalized with alcohol dehydrogenase (ADH), which catalyzes ethanol oxidation and drives localized NADH/NAD+ redox cycling. This enzymatic reaction alters the interfacial charge environment, influencing the ionic transport within the underlying KOH-modified gelatin layer (Gelatin A) and dynamically tuning the PEDOT:PSS channel conductivity. To further enhance charge redistribution, a PVDF:[BMIM][TFSI] ion gel is incorporated into the device structure. Surface morphology and optical properties were validated using atomic force microscopy (AFM) and UV-Vis spectroscopy, respectively. The sensor was fabricated on a flexible polyimide substrate via screen printing, enabling compatibility with wearable platforms. Ethanol vapor exposure elicited synaptic-like behavior, including cumulative response under prolonged exposure, reminiscent of olfactory adaptation. Paired-pulse facilitation (PPF) and long-term memory retention confirmed the device's neuromorphic characteristics. This platform offers a modular and scalable strategy for VOC detection, where enzyme selection can be tailored for specific analytes. The combination of biological recognition and electronic transduction establishes a promising route toward next-generation wearable gas sensors.

The transition from episodic clinical assessment to continuous physiological monitoring represents a transformative shift in biomedical engineering. This review comprehensively examines recent advancements in human-interfaced sensing systems, categorized into skin-attachable and implantable platforms. We analyze innovations in interface architectures designed to resolve the mechanical mismatch between rigid electronics and soft biological tissues. Key strategies include the utilization of elastomeric substrates, functional hydrogels, and high-performance nanomaterials to ensure mechanical compliance, biocompatibility, and stable electrical contact. Furthermore, this paper details diverse signal measurement modalities, ranging from electrochemical biosensors for metabolic biomarkers (e.g., glucose, lactate) to electrophysiological recordings (ECG, EEG, neural probes) and physical sensing (strain, pressure). Representative applications including smart contact lenses and wireless mouthguards highlight the potential of these technologies in real-world diagnostics. Despite significant progress in wireless telemetry and miniaturization, challenges regarding long-term biostability, enzymatic degradation, and the foreign body response persist. We conclude by discussing the future trajectory toward autonomous, closed-loop theranostic systems integrated with artificial intelligence and biodegradable materials, paving the way for ubiquitous, personalized health management.

Cross-linked polyvinyl alcohol (CX-PVA) enhances ion transport in OECTs, boosting transconductance, switching speed, and synaptic plasticity, thereby advancing neuromorphic computing and bioelectronic applications.

Organic electrochemical transistors (OECTs) are operated by the activity of the channel layer due to ion injection of the electrolyte. Currently, they are widely used in sensors, flexible, and wearable applications. OECTs have the potential to simulate synaptic model neuromorphic computing because they possess memory capabilities to express different states and can also be utilized as reservoir computing (RC) systems. Traditionally, OECTs face challenges with low mobility and the rapid return of ions to the electrolyte in the off state, which affects their synaptic properties. The blended P3HT:PS film significantly outperformed the pristine P3HT film, exhibiting a five-fold increase in performance and a high mu C* value of 95.74 F cm-1 V-1 s-1 . Its enhanced crystallinity contributed to sharper transfer curves and enhanced electrical properties. The film also demonstrated improved synaptic behavior, exhibiting a stronger paired-pulse facilitation (PPF) effect and delayed ion back diffusion. Long-term memory (LTM) retention reached 55.25 % after 1000 s, representing a 1.4-fold improvement over the pristine film (39.36 %). In RC tests, 4-bit sequences (1100 vs. 0011) yielded distinct change of excitatory postsynaptic current (Delta EPSC) values (-0.21 mu A vs. -0.58 mu A), confirming effective signal processing. These findings establish OECT-based devices as promising candidates for neuromorphic computing.

To maximize entropy extraction for hardware security, physically unclonable functions (PUFs) must move beyond binary encoding and adopt multi-valued state architectures. This transition necessitates extreme conductance variability at the device level to ensure reliable discrimination among a larger number of quantized output states. Here, we introduce particle-damaged graphene (PDG), which achieves conductance variability exceeding 10 11-fold, ranging from 3.02 x 10-14 to 2.95 x 10-3 A. This broad range enables the classification of 12 distinct output states that are separated by more than one order of magnitude in current. The PDG is fabricated using a microparticle-assisted lift-off process that induces controlled tearing, forming disordered conduction paths. We demonstrate an encryption scheme that combines static spatial randomness with tunable temporal entropy, enabling up to 450-bit variation in a 1,200-bit key under 1-mV bias. The generated keys pass National Institute of Standards and Technology randomness tests, providing a compact and scalable platform for high-entropy hardware security.

With the expansion of the virtual reality (VR) and augmented reality (AR) market, the close transmission of movement through human–machine interaction has become increasingly important. Polyurethane, a fiber used in various clothing and suits, possesses suitable elasticity and tensile strength. This makes it a material that can be closely attached to the skin without causing discomfort. However, since polyurethane is not a conductor, there is a disadvantage that it is impossible to detect electrical signals. Here, we synthesized polyurethane sulfonate (PUS) which is a hydrophilic modified polyurethane containing a high amount of sulfonate groups. This modified polyurethane shows the improved affinity with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) by intermolecular interaction of sulfonate group and PSS. Finally, an elastic strain sensor was fabricated with PEDOT:PSS coated on PUS over a large area of 100 cm2. This strain sensor induces resistance changes according to the elastic expansion of the PUS. The fabricated strain sensor was applied to finger joints and biceps, successfully detected movements corresponding to bending and expansion.