Search Results (1,439)

When poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is employed as the hole transport layer in visible/near-infrared photodetectors, the extraction and transport of holes are hindered by the accumulation of the PSS insulating phase at the interface. This accumulation results in an increase in contact resistance and creates a potential barrier for hole injection. This study introduces a self-assembled monolayer, (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), to modify PEDOT:PSS, effectively optimizing the interface of the hole transport layer. Such improvements lead to a reduction in recombination losses during charge transfer, a lower dark current, and improved energy level alignment in the device, thereby boosting the performance of visible/near-infrared photodetectors. The fabricated double hole layer photodetector exhibits a low dark current of (1.4 ± 0.6) × 10⁻⁵ A at −1 V bias and a switching ratio of up to 7.62 × 10⁵ at 0 V bias. The device achieves a responsivity of 0.31 A/W and a high specific detection rate of 3.23 × 10¹² Jones at a wavelength of 780 nm, which corresponds to the peak responsivity, showcasing enhanced detection capabilities. In comparison to a reference device based on PEDOT:PSS, the response speed, cutoff frequency, and linear dynamic range of the double hole layer device have been enhanced by 400%, 213%, and 81%, respectively, thereby better aligning with practical application requirements. This research presents a novel approach for the development of high-performance organic visible/near-infrared photodetectors. Full article

This review presents a comprehensive and thorough evaluation of recent developments in physical vapour deposition (PVD) radiofrequency (RF)-sputtered β-Ga₂O₃ thin-film-based solar-blind ultraviolet (UV) photodetectors (SB-UVPDs), emphasizing their potential for next-generation optoelectronic applications. The review highlights different photodetector architectures, the performance characteristics of SB-UVPDs, and an overview of the attributes of β-Ga₂O₃ that make it a promising wide-bandgap semiconductor for next-generation devices. Additionally, the working principle of the PVD RF magnetron sputtering technique is discussed briefly, with a particular focus on the influence of deposition parameters, including sputtering power, gas pressure, deposition time, target-to-substrate distance, and substrate temperature, on the resulting film’s crystallinity and morphology and the optical quality of SB-UVPDs. Moreover, the impact of post-deposition treatments, such as post-annealing and elemental doping, is also discussed here for SB-UVPDs. And finally, the electrical performance characteristics of SB-UVPDs are discussed categorically based on deposition parameters. Overall, this review establishes that PVD RF magnetron sputtering is a highly versatile and controllable technique for fabricating high-quality β-Ga₂O₃ thin film-based SB-UVPDs. By carefully optimizing deposition and post-processing parameters, the optoelectronic performance of β-Ga₂O₃-based SB-UVPDs can be effectively tuned, enabling their integration into next-generation high-performance optoelectronic and photonic systems. Full article

Graphene nanoribbons (GNRs) inherit the exceptional carrier mobility of graphene while offering tunable bandgaps, making them promising for high-performance optoelectronics. Here, we report a high-performance near-infrared photodetector based on a p-GNR/Al₂O₃/n-Si vertical heterojunction, where GNR is directly produced by dissociating double-walled carbon nanotubes (DWCNTs). The 10 nm Al₂O₃ interlayer serves as an effective barrier and passivation layer, suppressing dark current and enhancing interfacial charge separation. Under 1064 nm illumination, the device delivers outstanding performance. At −6 V bias, the responsivity and detectivity reach 159.55 A/W and 2.01 × 10¹² Jones, respectively. Notably, under zero-bias self-powered mode, it still achieves a high responsivity of 8.71 A/W, a detectivity of 1.15 × 10¹³ Jones, and a fast response time of 307.5 μs. These results fully validate the feasibility of GNR-based heterojunctions for high-performance optoelectronic devices and pave the way for their future integration into low-power, high-sensitivity photodetection systems and next-generation optoelectronic integrated circuits. Full article

Recently, self-powered MoS₂/GaAs photodetectors have attracted intensive attention. However, thermal processing following metal–electrode deposition tends to damage the lattice structure of MoS₂, leading to degraded device performance and poor consistency. In this work, Au/MoS₂/GaAs photodetectors are fabricated using two different methods of transferring Au (Tr-Au) and thermal evaporation Au (TE-Au), and their photoelectric performances are compared. It is found that, compared to TE-Au devices, the Tr-Au devices exhibit higher responsivity (45.29 A/W) and detectivity (3.11 × 10¹³ Jones). The underlying mechanisms are attributed to a significant reduction in defect traps in MoS₂ and a smooth MoS₂/GaAs heterojunction interface, which collectively increase photocurrent and suppress dark current. Therefore, the room-temperature Au transfer method shows great promise for the fabrication of high-performance optoelectronic devices. Full article

In this paper, we propose and demonstrate a sensitivity-enhanced sensing interrogation scheme based on an Optoelectronic oscillator (OEO), in which a switchable dual-passband microwave photonic filter (MPF) is introduced into the loop. The switchable dual-passband MPF is a combination of a modified fiber Mach–Zehnder interferometer (FMZI), an electro-optical modulator (EOM), a roll of dispersion compensating fiber (DCF), and a photodetector (PD). The dual-passband switching of the MPF can be achieved by simply adjusting the polarization state via rotating a polarization controller (PC) in the FMZI. The sensitivity can be improved by a factor of two by tracking the frequency corresponding to the central frequency of the high-frequency passband relative to the low-frequency passband. Temperature-sensing experiments were conducted to verify the concept of enhanced sensitivity. Experimental results on temperature sensing show that tracking low- and high-frequency OEO signals yields sensitivities of 5.23 MHz/°C and 10.84 MHz/°C, respectively, and temperature resolutions of 0.009 °C and 0.004 °C, thereby increasing sensitivity and resolution. Full article

Today, the rapid progress in non-invasive light–matter interaction analysis is transforming the landscape of biomedical and life sciences driven by low-intensity light detection technologies. As the complexity of photonic applications continues to grow, the importance of single-photon detection techniques becomes pivotal. Among them, Time-Correlated Single-Photon Counting (TCSPC) has become the gold standard for precise, time-resolved reconstruction of rapid and faint optical signals. However, TCSPC has long been constrained by pile-up distortion, which worsens with increasing acquisition speed, typically limiting it to 5% of the excitation frequency. To overcome the operational constraints of conventional implementations, a novel TCSPC acquisition methodology has been introduced, independent of photodetector dead time, excitation intensity, and prior optical signal knowledge, still enabling distortion-free reconstruction of the measured light profiles. In this context, the development of single-photon detectors with short dead time and low timing jitter becomes crucial. This work presents a single-photon detection module based on a Silicon Photomultiplier, which delivers 750 ps FWHM output pulses with a 33.5 ps RMS IRF. Its performance is showcased through fluorescence measurements employing the constraint-free TCSPC methodology, achieving a photon count rate up to 166% of the excitation frequency with a minimal lifetime estimation error of just −1.46%. Full article

In this study, zinc sulfide (ZnS) and manganese (Mn)-doped ZnS nanopowder were successfully prepared via a simple and cost-effective chemical precipitation method with various concentrations of Mn for use in UV photodetectors. The effects of Mn doping on the structural, morphological, and optoelectronic properties of ZnS nanopowder were studied. Structural analysis showed that all samples had a cubic structure with crystallite sizes approximately in the region of 2–3 nm. The morphological analysis using scanning electron microscopy confirmed the formation of well-dispersed spherical nanoparticles. Photoluminescence spectra show that Mn doping increased the luminescence intensity and caused a red shift in the emission peaks. Electrical properties such as conductivity and dielectric constant showed marked improvement with increasing Mn content. The conductivity increased from 3.7 mΩ⁻¹·m⁻¹ for pure ZnS to 6.3 mΩ⁻¹·m⁻¹ for the 1.03 mol% Mn²⁺ sample. The performance of photodetectors was evaluated under UV light. It was revealed that the photodetector based on a sample with 1.03 mol% Mn²⁺ reached an optimum state with an EQE of 9.8%, a detectivity of 4.65 × 10⁹ Jones, and a responsivity of 3.64 × 10⁻² A/W, indicating the effectiveness of Mn doping in improving the photo-generated carrier collection. Full article

Organic–inorganic hybrid halide perovskites have attracted extensive attention due to their excellent optoelectronic properties and potential applications in field-effect transistors (FET), light-emitting diodes (LEDs), and photodetectors. However, conventional three-dimensional (3D) perovskites are limited by intrinsic instability and ion migration. Two-dimensional Ruddlesden-Popper (2D RP) perovskites offer improved structural stability, but many systems still suffer from modest photoluminescence efficiency and limited charge-transport performance. In this work, a novel 2D RP perovskite, (C₆H₅NH₃)₂CsPb₂Cl₇, was designed and synthesized, where the anilinium ion (C₆H₅NH₃⁺) serves as the organic spacer. Structural characterization indicates that the material possesses high crystallinity and a smooth surface morphology. Optical measurements reveal a violet emission peak at 411 nm with a single-peak feature and a full width at half maximum (FWHM) of 10 nm. The bandgap is determined to be 3.1 eV. Time-resolved photoluminescence (TRPL) measurements show an average lifetime of 4 ns, and the photoluminescence quantum yield (PLQY) is 29.8%. Based on the measured PLQY and lifetime, the radiative and non-radiative recombination rates were estimated to be K_r ≈ 7.45 × 10⁷ s⁻¹ and K_nr ≈ 1.76 × 10⁸ s⁻¹, respectively, suggesting that radiative recombination is appreciable although non-radiative pathways remain present. FET measurements demonstrate an on/off current ratio of 10⁴ and a carrier mobility of 1.1 cm² V⁻¹ s⁻¹. Without any systematic optimization, (C₆H₅NH₃)₂CsPb₂Cl₇ exhibits relatively favorable emissive behavior and measurable field-effect charge transport performance when compared with structurally similar 2D RP perovskites reported under comparable, non-optimized conditions. This study expands the family of chloride-based 2D perovskites and provides a basis for future improvements in their recombination and field-effect transport properties. Full article

The design of photodetectors tailored to specific wavelengths in the mid-infrared (MIR) band serves as a foundational enabler for advancements in scientific research, industrial inspection, and environmental monitoring. Metasurfaces, composed of artificially engineered subwavelength unit cells, enable precise tailoring of light–matter interactions, achieving near-unity absorption at target wavelengths and thereby significantly boosting the sensitivity and spectral selectivity of MIR photodetectors. In this study, we developed a double-C open-loop metasurface and optimized its geometric parameters to realize high-efficiency absorption at 4 μm and 6 μm. Utilizing Te thin films fabricated via magnetron sputtering, we constructed a metasurface-enhanced mid-infrared photodetector based on Te thin films. The optimized metasurface structure enhances the light absorption of the Te thin film by a factor of eight within the target wavelength band. Ultimately, the metasurface-enhanced Te-based device achieved responsivities of 10.5 A/W and 13.7 A/W at 4 μm and 6 μm, respectively, representing enhancements of 3.6-fold and 3-fold compared to the initial Te thin-film device. This work provides a critical reference for enhancing the detection performance of infrared photodetectors at specific wavelengths through precise nanophotonic design. 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

In this study, we combined lead-free inorganic perovskite, CsSnI₃, with a transition metal chalcogenide, MoS₂, to develop a hybrid architecture for photodetectors utilizing the SCAPS-1D simulation tool. The performance of the photodetector was investigated across various thicknesses, doping concentrations, light intensities, and temperatures. An in-depth analysis of built-in potential, recombination rate, generation rate, quantum efficiency, I-V characteristics, and other performance parameters showed that the ideal thickness, doping density, bulk defect density, and interface defect density for enhanced photodetector performance are 800 nm, 1 × 10¹⁹ cm⁻³, 1 × 10¹⁴ cm⁻³, and 1 × 10¹⁰ cm⁻³, respectively. The photodetector exhibits optimal performance within the wavelength range of 200–500 nm and under illumination levels of 500–700 mW/m², maintaining a consistent responsivity of 0.59 A/W, a detectivity of 4.28 × 10¹³ Jones, a photocurrent of 34.50 mA/cm², and a low dark current of 10⁻⁶ mA/cm², with good thermal stability over a wide range of temperatures. The findings indicate that the CsSnI₃/MoS₂ heterojunction photodetector exhibits superior performance characterized by enhanced sensitivities throughout a broad operational range within the UV–blue visible spectrum and paves the way for the development of cost-effective, high-performance photodetectors in future optoelectronic applications. Full article

Infrared photodetectors are important for military, medical, and environmental applications. Dual-color quantum well infrared photodetectors (QWIPs) are attractive because they can provide multi-spectral information, but their performance is often limited by high dark current. In this study, we designed and fabricated two dual-color QWIPs. Sample A exhibits rectification-like dark-current behavior, whereas Sample B shows a nearly symmetric current–voltage characteristic together with an approximately two-order-of-magnitude reduction in dark current under the same operating condition. By combining secondary ion mass spectrometry (SIMS), scanning spreading resistance microscopy (SSRM), energy-band simulations, and optoelectronic characterization, we show that Sample B exhibits a larger disparity in effective carrier distribution between the two quantum-well groups than Sample A. The experimental results and simulations consistently indicate that this disparity, together with the higher barrier design, is associated with a redistribution of the internal potential and a stronger voltage drop across the lightly doped region, which is consistent with reduced thermally activated carrier transport. Although the lower carrier concentration in the lightly doped wells is accompanied by reduced blackbody responsivity, the stronger suppression of dark current leads to a higher peak blackbody detectivity under identical blackbody-illumination conditions. At 50 K and −1.5 V, the peak blackbody detectivity of Sample B is approximately four times that of Sample A. These results support the conclusion that combining barrier-height design with controlled inter-group carrier disparity is an effective strategy for tuning carrier transport and improving the peak blackbody detectivity trade-off in dual-color QWIPs within the conditions examined here. Full article

Photodetectors have undergone widespread, gradual application. Correlation detectors with varying properties are used in diverse fields. This review systematically summarizes the principles, properties, and applications of various photoelectric detectors reported in the past five years, compares their similarities and differences, and further discusses their respective advantages and disadvantages, applicable scenarios, and development prospects. The review covers self-powered detectors, which are very convenient and widely used in consumer electronics and portable wearable devices, and discusses the structural design and photoelectric performance of devices based on P–N junctions, perovskites, silicon–polymer hybrid composites, graphene, hybrid graphene/PbS quantum dot systems, and other novel material architectures. Compound photoelectric detectors enable multifunctional integration and intellectualization. At the same time, their high sensitivity and broad-spectrum response can expand the detection wavelength range to cover the ultraviolet, visible, and infrared bands and enhance the detection of weak optical signals. Finally, this review summarizes current challenges, including cumbersome fabrication processes, susceptibility of detection stability to environmental interference, and limited functionality, and focuses on recent advances in various photodetectors, where breakthroughs are expected. Full article

Polarity-tunable photocurrents provide an intrinsic decision variable that enables in-sensor computing within a single device, moving beyond simple intensity detection toward next-generation intelligent vision, yet traditional photodetectors are limited by static doping profiles and fixed junction polarities. To overcome this bottleneck, we propose a Te_0.61Se_0.39 nanowire device with polarity-tunable photoresponse for broadband optoelectronic logic operation via photocarrier diffusion under localized light illumination. By simultaneously harnessing temporal (pulse width), spatial (light positions), amplitude (light intensity), and bias, our polarity-tunable devices deterministically realize the four fundamental Boolean logic gates (AND, NAND, XNOR, XOR), with a responsivity of 1.39 A/W and a specific detectivity of 1.75 × 10¹⁰ Jones across the visible to mid-wave infrared spectrum. We further showcased its scalability by constructing a two-layer composite Boolean circuit through the integration of optoelectronic AND and NAND gates. Practical applications in optical encoding/decoding transmission and differential perception highlight its broad functional adaptability. This work establishes a paradigm for broadband polarity devices in low-dimensional nanowires, providing a versatile platform for optoelectronic logic and differential imaging applications. Full article

Self-powered photodetectors have attracted widespread attention in Internet of Things applications due to their low power consumption and high sensitivity. In this study, plasmonic self-powered poly(3-hexylthiophene)/zinc oxide (P3HT/ZnO) heterojunction photodetectors incorporating silver triangular nanoplates (AgTNPs) were fabricated using sol–gel and spin-coating techniques. The experimental results demonstrate that the incorporation of AgTNP nanostructures significantly enhances the photoelectric conversion efficiency of the plasmonic P3HT/AgTNPs/ZnO photodetectors across both the ultraviolet and visible spectral regions. The responsivity enhancement ratio of the plasmonic devices reached its maximum under illumination at a wavelength of 525 nm. Compared with the reference P3HT/ZnO device, the responsivity values of the P3HT/AgTNPs-1/ZnO and P3HT/AgTNPs-2/ZnO devices increased by factors of 3.24 and 4.21, respectively. The optimal P3HT/AgTNPs-2/ZnO device exhibited responsivity values of 9.49, 10.80, and 10.47 mA/W under irradiation at wavelengths of 440 nm, 460 nm, and 525 nm, respectively. The mechanism of performance enhancement induced by the plasmonic AgTNPs is also discussed. This work demonstrates that embedding triangular plasmonic metal nanoplates within semiconductor heterojunctions constitutes an effective strategy for performance enhancement, providing new insights for the rational design of high-performance optoelectronic devices. Full article