Search Results (103)

The field of infrared (IR) photodetection is undergoing rapid development through the emergence of solution-processable nanoparticle (NP)-based materials and fabrication strategies. This review critically examines recent advances in fabrication approaches for NP-based IR detectors, emphasizing the relationship between synthesis, surface engineering, deposition processes, and device architecture in determining detector performance. Representative material platforms are discussed, including colloidal quantum dots (CQDs) such as PbS and HgTe, which enable tunable operation from the near-infrared (NIR) and short-wave infrared (SWIR) to selected mid-wave (MWIR), long-wave (LWIR), and emerging very-long-wave infrared (VLWIR) regimes depending on material composition and operating conditions. Further platforms including plasmonic metal NPs, black phosphorus, and topological nanomaterials are evaluated for their unique mechanisms of optical enhancement and broadband response. Fabrication approaches including continuous-flow synthesis, ligand exchange, blade coating, inkjet printing, electrophoretic deposition, and other scalable solution-processing methods are analyzed with respect to their influence on film quality, charge transport, interface engineering, and integration compatibility. The review further compares major device architectures, including photoconductors, photodiodes, plasmonic absorbers, and phototransistors, using key performance metrics such as specific detectivity (D*), responsivity (R), response speed, and operating temperature, while emphasizing the importance of measurement conditions in cross-platform comparisons. Critical challenges including dark-current generation, 1/f noise, transport limitations associated with ligand chemistry, environmental instability of narrow-bandgap materials, manufacturability constraints, and toxicity considerations are also discussed. Emerging directions such as neuromorphic sensing, CMOS-compatible integration, and sustainable lead-free nanomaterials are highlighted. By linking nanoscale material design and fabrication processes to device-level performance, this review provides a framework for advancing NP-based IR technologies toward scalable and application-relevant sensing systems. Full article

The article discusses promising methods of data transmission using laser radiation. A comparative analysis of optical (non-laser) and laser communication was conducted, and experimental modeling of two channels was performed, including a mock-up. The optical communication channel model is based on an amplitude-modulated infrared (IR) LED and a narrowly focused laser transmitter. The model of the laser communication channel included a semiconductor laser source and a phototransistor receiver. As part of the work, the main characteristics of these communication channels were evaluated, including the maximum data transfer rate, maximum communication range, and quantitative measures of noise immunity for both channels. Significant differences were revealed, in particular, packet errors of 3–5 bits in a row were observed in the IR channel, which is explained by the inertia of the analog circuits of the receiving part. The laser system, on the contrary, demonstrated a uniform distribution of single errors due to the discrete nature of interference from background illumination. The article shows that both methods of organizing communication can be effectively used for information exchange tasks with a short distance between objects, particularly in groups of unmanned aerial vehicles. Full article

Cost-effective, fluorescence-based biodiagnostic devices have the potential to expand point-of-care (POC) testing in resource-limited settings, thereby creating new opportunities for accessible and decentralised diagnostics. The objective of this study is to investigate the performance of a newly designed and simplified system that uses several cost-effective sensors for use in a fluorescence-based biodiagnostic setup. A collecting setup that includes an elliptical mirror to focus emitted fluorescence onto the semiconductor sensors was designed for an intensity-based readout. The readout was realised by various photodiodes, photoresistors, phototransistors and one multi-pixel photon counter (MPPC). Over a range of fluorophore concentrations using serial dilutions of Rhodamine B (RhB), the limit of detection (LOD) and limit of quantification (LOQ) at system level were evaluated. With the exception of the photodiodes, the system demonstrated promising performance with all sensors. The system using the photoresistors achieved the lowest LOD but showed limited repeatability, while the system using the MPPC and phototransistors exhibited high repeatability. A proof-of-concept demonstrated the feasibility of a photoresistor-based configuration by using a sandwich immunoassay for the detection of the antigen Human Epidermal growth factor Receptor 2 (HER2) (100 nM). While this study has not yet encompassed the full spectrum of clinically relevant concentrations, it has yielded valuable insights to enable further enhancements, without the necessity for highly specialised or costly equipment. The limitations and necessary improvements for further developments are discussed. Full article

Molybdenum disulfide (MoS₂) is a compelling candidate for visible-light detection due to its strong optical absorption and tunable bandgap, yet the development of high-performance MoS₂ photodetectors remains limited by challenges in scalable integration, low-voltage operation, and efficient photoresponse. Here, we report an ion-gel-assisted transfer strategy that enables the fabrication of large-area MoS₂/ion gel films that are suitable for low-power phototransistor applications. The transferred MoS₂/ion gel stack is laminated onto an indium-tin-zinc-oxide (ITZO) layer on a glass substrate to fabricate a MoS₂/ITZO heterojunction phototransistor, with the ion gel serving as an ultrathin, high-capacitance gate dielectric. The resulting phototransistor exhibits a field-effect mobility of 4.12 cm²/Vs, an on/off current ratio of 4.9 × 10⁵, and a subthreshold swing of 0.17 V/dec. Under 635, 520, and 405 nm illumination with a power density of 4.5 mW/cm², it achieves responsivities of 0.58, 1.82, and 5.56 A W⁻¹ and detectivities of 5.90 × 10⁹, 1.86 × 10¹⁰, and 5.68 × 10¹⁰ Jones, respectively. These findings demonstrate that the ion-gel-assisted transfer process offers a robust route to high-performance, low-voltage photodetection and provides a promising platform for next-generation optoelectronic technologies. Full article

Amorphous gallium oxide thin-film transistor photodetectors are promising for ultraviolet detection because of their wide bandgap and low dark current. Magnetron sputtering is compatible with low-temperature processing, but device performance is sensitive to sputtering conditions. Poor parameter choices can introduce oxygen vacancies and interface charges, degrading optoelectronic performance. Here, a three-factor, three-level orthogonal design is used to vary sputtering power, Ar/O₂ flow ratio, and film thickness. Nine device sets are fabricated and compared based on transfer characteristics and transient photocurrent–time (I-t) responses measured at a wavelength of 254 nm, with clear differences observed among process combinations. To identify the origin of these differences, representative samples with significant responsivity variations were modeled using TCAD. By fitting the simulated I-t curves to measured transients, the interface fixed charge density and defect-state densities were extracted, and the photon absorption distribution of different samples was analyzed. This analysis, from both defect and UV absorption perspectives, revealed the reasons for the differences in responsivity. The absorption coefficients at 254 nm measured by ellipsometry for the two samples were also compared, and the absorption trends observed in both the simulation and ellipsometry were consistent, confirming the accuracy of the simulation results. This work presents an integrated experimental and TCAD approach for process optimization and mechanistic analysis of a-GaO_x TFT-PDs. Full article

Heterojunctions combining graphene with transition metal dichalcogenides (TMDCs) have garnered considerable interest in phototransistor research. Molybdenum disulfide (MoS₂) can be well combined with graphene owing to its excellent and special bandgap characteristics. In this study, a photoelectric transistor is designed and fabricated based on a graphene–molybdenum disulfide (MoS₂) van der Waals heterojunction. Its novelty lies in constructing a vertical heterojunction architecture with a well-defined structure, clear interface, and easy gate modulation. It fully utilizes the high mobility of graphene and the appropriate bandgap of MoS₂ to achieve efficient light absorption and carrier transport. The device exhibits a good photoelectric response and stability at room temperature, with key performance indicators including the following: a responsivity of 0.5023 mA/W, and a dark current of approximately 10⁻¹¹ A at a gate voltage of 0 V and approaching 10⁻¹⁰ A at 30 V; when the light intensity is 1000 mW/cm², the photocurrent reaches the 10⁻⁸ A level, demonstrating the synergistic modulation capability of gate voltage and light intensity. Although its responsivity is lower than some high-performance heterojunction devices, this device has advantages such as a simple structure, controllable preparation, stable room-temperature operation, and the potential for a broad-spectrum response, showing good application prospects in flexible electronics and integrated optoelectronic systems. This study provides an experimental basis and technical path for the development of two-dimensional material heterojunctions in programmable, multifunctional optoelectronic devices. Full article

Near-infrared organic photodetectors (NIR-OPDs) are emerging as versatile platforms for flexible and low-cost optical sensing, yet achieving high-performance in the NIR region remains difficult remains challenging due to intrinsic trade-offs at both the material and device levels, due to the inherent balance required among bandgap narrowing, exciton dissociation, charge transport, and dark-current suppression. This review provides a concise overview of OPD operating mechanisms and the performance metrics governing sensitivity and noise. We highlight recent molecular-engineering strategies—core fluorination, asymmetric π-bridge design, fused-ring rigidification, and polymer backbone/side-chain tuning—that effectively enhance intermolecular ordering, reduce energetic disorder, and extend NIR absorption. Progress in all-polymer detectors and ambipolar phototransistors further demonstrates improved stability and broadened detection capability. Additionally, emerging applications, including NIR communication, biosignal monitoring, flexible imaging, and biometric recognition, showcase the expanding utility of NIR-OPDs. Remaining challenges include pushing detection beyond 1200 nm, simplifying synthesis, and improving long-term stability. Overall, advances in low-bandgap molecular design and device engineering continue to accelerate the practical adoption of NIR-OPDs. Full article

Two-dimensional (2D) materials demonstrate significant potential in photodetector technology. They offer high sensitivity, wide spectral range, flexibility and transparency, especially in infrared detection, promising advancements in wearable and flexible electronics. This study explores the application of 2D materials in high-performance photodetectors. Rhenium diselenide (ReSe₂) was used as the channel, and graphene (Gr) was inserted between ReSe₂ and SiO₂ as the gate electrode to enhance device performance. A ReSe₂/Gr heterostructure field-effect transistor (FET) was fabricated to investigate the role of Gr in improving the optoelectronic properties of ReSe₂ phototransistors. Specifically, the ReSe₂ FET without Gr auxiliary layer demonstrates a responsivity (R) of 294 mA/W, an external quantum efficiency (EQE) of 68.75%, and response times as brief as 40/62 ms. Compared with the ReSe₂ phototransistor, the ReSe₂/Gr phototransistor exhibits significantly improved photoresponsivity and EQE, with the photoresponsivity enhanced by a factor of ap-proximately 3.58 and the EQE enhanced by a factor of approximately 3.59. These enhancements are mainly attributed to optimization of interfacial band alignment and the strengthened photogating effect by Gr auxiliary layer. This research not only underscores the pivotal role of Gr in boosting the capabilities of 2D photodetectors but also offers a viable strategy for developing high-performance photodetectors with 2D materials. Full article

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