Search Results (95)

Polymeric semiconductors have rapidly evolved from early conductive polymers, such as polyacetylene, to high-performance donor–acceptor copolymers, offering a unique combination of mechanical flexibility, solution processability, and tunable optoelectronic properties. These advancements have positioned polymeric semiconductors as versatile materials for next-generation electronics, including wearable, stretchable, and bio-integrated devices, IoT systems, and soft robotics. In this review, we systematically present the fundamental principles of polymeric semiconductors, including electronic structure, charge transport mechanisms, molecular packing, and solid-state morphology, and elucidate how these factors collectively govern device performance. We further discuss recent advances in synthesis strategies, thin-film processing techniques, molecular doping, and interface engineering, emphasizing their critical roles in improving operational stability, charge-carrier mobility, and energy efficiency. Key applications—such as organic photovoltaics, field-effect transistors, neuromorphic devices, and memristors—are analyzed, with a focus on the intricate structure–property–performance relationships that dictate functionality. Finally, we highlight emerging directions and scientific innovations, including sustainable and degradable polymers, hybrid and two-dimensional polymer systems, and novel strategies to enhance device stability and performance. By integrating fundamental polymer science with device engineering, this review provides a comprehensive, structured, and forward-looking perspective, identifying knowledge gaps and offering insights to guide future breakthroughs and the rational design of high-performance, multifunctional, and environmentally responsible polymeric electronic devices. Full article

In recent years, indium-oxide thin-film transistors (IOTFTs) have been developed with high electron mobility, low power consumption, and good environmental stability. A major challenge in current IOTFTs research lies in developing high-performance devices through low-temperature processes while simultaneously expanding their functionality into photonic applications. Our study proposes a low-temperature annealing method for high-performance IOTFTs fabrication, combining substrate heating and a multi-stage annealing process. The optimized device exhibits a device mobility of 47.99 cm²/V·s, a threshold voltage of 2.8 V, a subthreshold swing (SS) of 742.83 mV/dec, and good stability under bias stress tests. Building upon the IOTFTs, we extend the functionality to photonic applications by integrating poly[[2,3,5,6-tetrahydro-2,5-bis(2-octyldodecyl)-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-2,5-thiophenediylthieno[3,2-b]thiophene-2,5-diyl-2,5-thiophenediyl] (DPPDTT) photoresponsive layer, achieving a phototransistor with responsivity of 3.7 A/W and detectivity of 5.86 × 10¹¹ Jones at 850 nm near-infrared light. This work provides a new approach for fabricating high-performance indium-oxide thin-film transistors and phototransistors with low-temperature annealing. Full article

Organic phototransistors exhibit considerably higher photoresponsivity than diode-like photodetectors owing to gate-field-effect amplification. However, the conventional definition of photoresponsivity (R) fails to accurately capture the photoresponsivity trends of transistor-based photodetectors. This study systematically investigates the impact of device geometry—specifically the width-to-length (W/L) ratio and photosensitive area—on the responsivity and photocurrent of organic phototransistors. The experimental results reveal that increasing the W/L ratio or decreasing the device area substantially enhances responsivity. A detailed analysis based on the definition of responsivity is presented herein. Finally, we introduce a channel-width-normalized responsivity to compensate for geometric effects, enabling a more accurate evaluation of device performance across different device structures. Overall, our results indicate the potential for optimizing organic phototransistors by tuning their geometric parameters. Full article

Artificial photoelectric synapses exhibit great potential for overcoming the Von Neumann bottleneck in computational systems. All-inorganic halide perovskites hold considerable promise in photoelectric synapses due to their superior photon-harvesting efficiency. In this study, a novel wavy-structured CsPbBr₃/ZnO hybrid film was realized by depositing zinc oxide (ZnO) onto island-like CsPbBr₃ film via atomic layer deposition (ALD) at 70 °C. Due to the capability of ALD to grow high-quality films over small surface areas, dense and thin ZnO film filled the gaps between the island-shaped CsPbBr₃ grains, thereby enabling reduced light-absorption losses and efficient charge transport between the CsPbBr₃ light absorber and the ZnO electron-transport layer. This ZnO/island-like CsPbBr₃ hybrid synaptic transistor could operate at a drain-source voltage of 1.0 V and a gate-source voltage of 0 V triggered by green light (500 nm) pulses with low light intensities of 0.035 mW/cm². The device exhibited a quiescent current of ~0.5 nA. Notably, after patterning, it achieved a significantly reduced off-state current of 10⁻¹¹ A and decreased the quiescent current to 0.02 nA. In addition, this transistor was able to mimic fundamental synaptic behaviors, including excitatory postsynaptic currents (EPSCs), paired-pulse facilitation (PPF), short-term to long-term plasticity (STP to LTP) transitions, and learning-experience behaviors. This straightforward strategy demonstrates the possibility of utilizing neuromorphic synaptic device applications under low voltage and weak light conditions. Full article

This study introduces a comprehensive physical modeling framework for phototransistors based on quasi-two-dimensional transition metal dichalcogenides, with a particular emphasis on MoS₂. By integrating electromagnetic simulations of optical absorption with semiconductor transport calculations, the model captures both dark and photocurrent behaviors across diverse operating conditions. For 20 nm MoS₂ films, the model reproduces the experimental transfer characteristics with a threshold voltage accuracy better than 0.1 V and achieves quantitative agreement with photocurrent and dark current values across the full range of gate voltages, with the worst-case deviation not exceeding a factor of seven. Additionally, the model captures a three-order-of-magnitude increase in the photocurrent as the MoS₂ thickness varies from 4 nm to 40 nm, reflecting the strong thickness dependence observed experimentally. A key insight from the study is the critical role of defect states, including traps, impurities, and interfacial imperfections, in governing the dark current and photocurrent under channel pinch-off conditions (Vg < −1.0 V). The model successfully replicates the qualitative trends observed in experimental devices, highlighting how small variations in film thickness, doping levels, and contact geometries can significantly influence device performance, in agreement with published experimental data. These findings underscore the importance of precise defect characterization and optimization of material and structural parameters for 2D-material-based phototransistors. The proposed modeling framework serves as a powerful tool for the design and optimization of next-generation phototransistors, facilitating the integration of 2D materials into practical electronic and optoelectronic applications. Full article

We propose a novel ultraviolet (UV) phototransistor (PT) architecture based on an AlGaN/GaN high electron mobility transistor (HEMT) with a buried p-GaN layer. In the dark, the polarization-induced two-dimensional electron gas (2DEG) at the AlGaN/GaN heterojunction interface is depleted by the buried p-GaN and the conduction channel is closed. Under UV illumination, the depletion region shrinks to just beneath the AlGaN/GaN interface and the 2DEG recovers. The retraction distance of the depletion region during device turn-on operation is comparable to the thickness of the AlGaN barrier layer, which is an order of magnitude smaller than that in the conventional p-GaN/AlGaN/GaN PT, whose retraction distance spans the entire GaN channel layer. Consequently, the proposed device demonstrates significantly enhanced weak-light detection capability and improved switching speed. Silvaco Atlas simulations reveal that under a weak UV intensity of 100 nW/cm², the proposed device achieves a photocurrent density of 1.68 × 10⁻³ mA/mm, responsivity of 8.41 × 10⁵ A/W, photo-to-dark-current ratio of 2.0 × 10⁸, UV-to-visible rejection ratio exceeding 10⁸, detectivity above 1 × 10¹⁹ cm·Hz^1/2/W, and response time of 0.41/0.41 ns. The electron concentration distributions, conduction band variations, and 2DEG recovery behaviors in both the conventional and novel structures under dark and weak UV illumination are investigated in depth via simulations. Full article

We report an ion-gel-gated amorphous indium gallium zinc oxide (a-IGZO) optoelectronic neuromorphic transistors capable of synaptic emulation in both photoelectric dual modes. The ion-gel dielectric in the coplanar-structured transistor, fabricated via ink-jet printing, exhibits excellent double-layer capacitance (>1 μF/cm²) and supports low-voltage operation through lateral gate coupling. The integration of ink-jet printing technology enables scalable and large-area fabrication, highlighting its industrial feasibility. Electrical stimulation-induced artificial synaptic behaviors were successfully demonstrated through ion migration in the gel matrix. Through a simple and controllable oxygen vacancy engineering process involving low-temperature oxygen-free growth and post-annealing process, a sufficient density of stable subgap states was generated in IGZO, extending its responsivity spectrum to the visible-red region and enabling wavelength-discriminative photoresponses to 450/532/638 nm visible light. Notably, the subgap states exhibited unique interaction dynamics with low-energy photons in optically triggered pulse responses. Critical synaptic functionalities—including short-term plasticity (STP), long-term plasticity (LTP), and paired-pulse facilitation (PPF)—were successfully simulated under both optical and electrical stimulations. The device achieves low energy consumption while maintaining compatibility with flexible substrates through low-temperature processing (≤150 °C). This study establishes a scalable platform for multimodal neuromorphic systems utilizing printed iontronic architectures. Full article

Monolayer MoS₂ has been widely researched in high performance phototransistors for its high carrier mobility and strong photoelectric conversion ability. However, some defects in MoS₂, such as vacancies or impurities, provide more possibilities for carrier recombination; thus, restricting the formation of photocurrents and resulting in decreased responsiveness. Herein, all-inorganic CsPbBr₃ perovskite quantum dots (QDs) with high photoelectric conversion efficiency and light absorption coefficients are introduced to enhance the responsivity of a 2D MoS₂ phototransistor. The CsPbBr₃/MoS₂ heterostructure has a type II energy band, and it has a high responsivity of ~1790 A/W and enhanced detectivity of ~2.4 × 10¹¹ Jones. Additionally, the heterostructure CsPbBr₃/MoS₂ enables the synergistic effect mechanism of photoconduction and photogating effects with the gate tunable photo-response, which could also contribute to an improved performance of the MoS₂ phototransistor. This work provides new strategies for performance phototransistors and is expected to play an important role in many fields, such as optical communication, environmental monitoring and biomedical imaging, and promote the development and application of related technologies. Full article

In this paper, a silicon carbide (SiC) phototransistor based on an open-base structure was fabricated and used as a radiation detector. In contrast to the exposed and thin sensitive region of traditional photo detectors, the sensitive region of the radiation detector was much thicker (30 μm), ensuring the high energy deposition of radiation particles. The response properties of the fabricated SiC npn radiation detector were characterized by high-energy X-ray illumination with a maximum X-ray photon energy of 30 keV. The SiC npn detector featured stable and clear response to the X-ray within 0.0766 Gy∙s⁻¹ to 0.766 Gy∙s⁻¹ below 300 V. Due to to the low leakage current of less than 1 nA and the fully depleted sensitive region, the bipolar-transistor-modeled SiC npn detector exhibited a clear common-emitter current gain of 5.85 at 200 V (under 0.383 Gy∙s⁻¹), where the gain increased with bias voltage due to the Early effect and reached 7.55 at 300 V. In addition, the transient response of the SiC npn detector revealed a longer delay time than the SiC diode of the same size, which was associated with the larger effective capacitance of the npn structure. The npn detector with internal gain showed great potential in radiation detection. Full article

We investigate the inorganic/organic hybrid vertical phototransistor (VPT) by integrating an atomic layer deposition-processed ZnO (ALD-ZnO) transistor with a prototype poly(3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PC₆₁BM) blend organic photodiode (OPD) based on an encapsulated source electrode geometry, and discuss the device mechanism. Our preliminary studies on reference P3HT:PC₆₁BM OPDs show non-ohmic electron injection between the ALD-ZnO and P3HT:PC₆₁BM layers. However, the ALD-ZnO layer enables the accumulation of photogenerated holes under negative bias, which facilitates electron injection upon illumination and thereby enhances the external quantum efficiency (EQE). This mechanism underpins the photoresponse in the VPT. Furthermore, we demonstrate that the gate field in the VPT effectively modulates electron injection from the ALD-ZnO layer to the top OPD, resulting in the VPT operating as a non-ohmic OPD in the OFF state and as an ohmic OPD in the ON state. Benefiting from the unique transistor geometry and gate modulation capability, this hybrid VPT can achieve an EQE of 45,917%, a responsivity of 197 A/W, and a specific detectivity of 3.4 × 10¹² Jones under 532 nm illumination and low drain-source voltage (V_ds = 3 V) conditions. This transistor geometry also facilitates integration with various OPDs and the miniaturization of the ZnO channel area, offering an ideal basis for the development of highly efficient VPTs and high-resolution image sensors. Full article

This review provides a comprehensive overview of recent advancements in the synthesis, properties, and applications of organic materials in the optoelectronics sector. The study emphasizes the critical role of organic materials in the development of state-of-the-art optoelectronic devices such as organic solar cells, organic thin-film transistors, and OLEDs. The review further examines the structure, operational principles, and performance metrics of organic optoelectronic devices. Organic materials have emerged as promising candidates due to their low-cost production and potential for large-area or flexible substrate applications. Additionally, this review highlights the physical mechanisms governing the optoelectronic properties of high-performance organic materials, particularly photoinduced processes relevant to charge carrier photogeneration. It discusses the unique benefits of organic materials over traditional inorganic materials, including their light weight, simple processing, and flexibility. The report delves into the challenges related to stability, scalability, and performance, while highlighting the wide range of electronic properties exhibited by organic materials, which are critical for their performances in optoelectronic devices. Furthermore, it addresses the need for further research and development in this field to achieve consistent performance across different types of devices. Full article

Organic phototransistors, renowned for their exceptional biocompatibility, hold promise in phototherapy for tracking the efficacy of photosensitive drugs within treatment areas. Nevertheless, it has been found that organic semiconductors are less effective in detecting ultraviolet (UV) light because of their narrow bandgap. Here, we show that UV photodetection in phototransistors using donor-acceptor (D-A) polymer semiconductors can be significantly enhanced by incorporating PCBM nanocrystals. This integration results in a band mismatch between the nanocrystals and the D-A polymer at the interface. These nanocrystals also demonstrate a notable capability of modulating threshold voltage under UV light. The devices incorporating nanocrystals exhibit a photoresponsivity of 0.16 A/W, surpassing the photoresponsivity of the devices without nanocrystals by 50%. The specific detection rate of devices with nanocrystals is around 2.00 × 10¹⁰ Jones, which is twice as high as that of devices without nanocrystals. The presented findings offer a potential avenue to improve the efficiency of polymer phototransistors for UV detection. Full article

We demonstrate a Sn-doped monoclinic gallium oxide (β-Ga₂O₃)-based deep ultraviolet (DUV) phototransistor with high area coverage and manufacturing efficiency. The threshold voltage (V_T) switches between negative and positive depending on the β-Ga₂O₃ channel thickness and doping concentration. Channel depletion and Ga diffusion during manufacturing significantly influence device characteristics, as validated through computer-aided design (TCAD) simulations, which agree with the experimental results. We achieved enhancement-mode (e-mode) operation in <10 nm-thick channels, enabling a zero V_G to achieve a low dark current (1.84 pA) in a fully depleted equilibrium. Quantum confinement in thin β-Ga₂O₃ layers enhances UV detection (down to 210 nm) by widening the band gap. Compared with bulk materials, dimensionally constrained optical absorption reduces electron–phonon interactions and phonon scattering, leading to faster optical responses. Decreasing β-Ga₂O₃ channel thickness reduces V_T and V_G, enhancing power efficiency, dark current, and the photo-to-dark current ratio under dark and illuminated conditions. These results can guide the fabrication of tailored Ga₂O₃-based DUV phototransistors. Full article

Phototransistors are three-terminal photodetectors that usually have a higher photocurrent gain than photodiodes due to the amplification of the gate electrode. In this work, a broad spectral phototransistor based on copper phthalocyanine (CuPc) and a Cs₃Bi₂I₉ (CBI) heterojunction is fabricated by the full vacuum evaporation method. Due to the complementary UV–visible absorption of CuPc and CBI, the device exhibits superior performance under three different types of visible light illumination. The experimental results show that the structure of the organic/perovskite heterojunction active layer has the characteristics of good compatibility and a simple process. Meanwhile, by utilizing the superior light-absorption characteristics of perovskite materials and the strong exciton dissociation efficiency of a hetero-type heterojunction interface, the CuPc/CBI-PT exhibits a higher photoresponsivity, photosensitivity, specific detection rate, and lower operating voltage than the CuPc reference device. The stability test shows that the CuPc/CBI-PT can still obtain a 0.73 A/W photoresponsivity under 660 nm light illumination after being stored in the air for 360 h without any packaging. This indicates that the organic/perovskite heterojunction PT may be a good choice for the preparation of high-performance photodetectors. Full article

The optically gated transistor (OGT) has been previously demonstrated as a viable selector device for memristor devices, and may enable optical addressing within cross-point arrays. The OGT current–voltage response is similar to a MOSFET device, with light activating the gate instead of voltage. The OGT also provides a naturally built-in compliance current for a series resistive memory element, determined by the incident light intensity on the gate, thus keeping the integrated periphery circuitry size and complexity to a minimum for a memory array. The OGT gate comprises an amorphous Ge₂Se₃ material that can readily be doped with other elements to alter the transistor’s electrical properties. In this work, we explore the operation of the OGT when the Ge₂Se₃ gate material is doped with the Group IVA elements C, Si, Sn, and Pb. The dopant atoms provide changes to the optical and electrical properties that allow key electrical properties such as the dark current, photocurrent, switching speed, and threshold voltage to be tuned. Full article