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Ultrasensitive MoS2 photodetector by serial nano-bridge multi-heterojunction
摘要： The recent reports of various photodetectors based on molybdenum disulfide (MoS2) field effect transistors showed that it was difficult to obtain optoelectronic performances in the broad detection range [visible–infrared (IR)] applicable to various fields. Here, by forming a mono-/multi-layer nano-bridge multi-heterojunction structure (more than > 300 junctions with 25 nm intervals) through the selective layer control of multi-layer MoS2, a photodetector with ultrasensitive optoelectronic performances in a broad spectral range (photoresponsivity of 2.67 × 106 A/W at λ = 520 nm and 1.65 × 104 A/W at λ = 1064 nm) superior to the previously reported MoS2-based photodetectors could be successfully fabricated. The nano-bridge multi-heterojunction is believed to be an important device technology that can be applied to broadband light sensing, highly sensitive fluorescence imaging, ultrasensitive biomedical diagnostics, and ultrafast optoelectronic integrated circuits through the formation of a nanoscale serial multi-heterojunction, just by adding a selective layer control process.
关键词： photodetector,nano-bridge,multi-heterojunction,MoS2,optoelectronic performances
更新于2025-09-19 17:13:59
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Hydrothermally-Grown TiO2 Thin Film-Based Metal–Semiconductor–Metal UV Photodetector
摘要： A metal–semiconductor–metal (MSM) ultraviolet photodetector has been fabricated by using hydrothermally-grown TiO2 thin films. Ag paint was used as a contact electrode which showed the good ohmic contact between the metal–semiconductor junctions. The effect of deposition time on the structural, morphological and photodetector properties have been studied. The prepared TiO2 thin films are polycrystalline and show a rutile crystal structure with the preferred orientation along the (110) plane. The MSM UV photodetector was illuminated under a UV lamp with an intensity of 1.8 lW/cm2 and at 5-V bias. The photocurrent of the device increased linearly with the applied voltage. The maximum photocurrent of 3.96 lA was obtained for the film deposited at 5 h and maximum spectral photoresponsivity was 13.29 A/W. The device showed a fast optical switching behavior. The high responsivity and fast photoresponse shows that fabricated TiO2 detectors are good candidates for ultraviolet photodetectors.
关键词： MSM UV photodetector,Titanium dioxide,photoresponsivity,hydrothermal method
更新于2025-09-19 17:13:59
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Facile synthesis of ZnO microrod photodetectors by solid-state reaction
摘要： In this study, ZnO microrods were directly synthesized via a single-step solid-state reaction using ZnO powders mixed with graphite without a catalyst under an air atmosphere, instead of using vacuum systems and flowing gases. The structure, growth mechanism, and electrical and optical properties of the microrods were investigated under varying growth conditions. The high-resolution transmission electron microscopy images confirmed the formation of single-crystal ZnO microrods. The photoluminescence spectra of the microrods showed green emission, suggesting the formation of non-stoichiometric ZnO microrods due to the formation of oxygen vacancies during sintering. The length and width of the ZnO microrods could be modulated by controlling the graphite content, sintering temperature, and residual time. A simple photodetector consisting of a single-crystal ZnO microrod on a SiO2-coated Si substrate was fabricated. The photodetector exhibited a linear current–voltage curve in visible light. The slope of the curve increased under ultraviolet (UV) irradiation, maintaining a linear shape of the curve. The curve reversibly returned to the initial shape in the absence of UV illumination. The UV on-off current ratio increased because of the decrease in the off-current by compensating for the oxygen vacancies through annealing in an oxygen atmosphere. Thus, in this study, we proposed a simple and efficient approach to fabricate single-crystal ZnO microrods for application in low-cost photodetectors.
关键词： oxygen vacancies,solid-state reaction,single-crystal,ZnO microrods,photodetector
更新于2025-09-19 17:13:59
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Reconfigurable Surface Plasmon Resonance Photodetector with a MEMS Deformable Cantilever
摘要： Plasmonic photodetectors have many useful characteristics, such as wavelength- or polarization-specific photodetection. Although reconfigurable plasmonic structures have been intensively studied, reconfiguration of the optical characteristics of a plasmonic photodetector has not yet been reported. Here, we report a gold diffraction-grating-type plasmonic photodetector that reconfigures its optical characteristics with a MEMS deformable cantilever. By reconfiguring the photodetector characteristics using an angular scan of the cantilever over ?21 ~ 21 degrees, the peak shifts of the photocurrent signal waveform are found to depend on the wavelength over 1200 nm ~ 1500 nm, which is consistent with SPR theory. The proposed reconfigurable plasmonic photodetector allowed us to obtain spectroscopic information of the light in a demonstration experiment.
关键词： Schottky-barrier,Surface Plasmon Resonance,MEMS,Near-infrared light,Spectrometer,Photodetector
更新于2025-09-19 17:13:59
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Improving the photo-current of poly(3-hexylthiophene): [6,6]-phenyl C71 butyric acid methyl-ester photodetector by incorporating the small molecules
摘要： This work demonstrates the improvement in photo-current response of poly(3-hexylthiophene) (P3HT)-based thin film organic photodetector by introducing [6,6]-phenyl C71 butyric acid methyl-ester (PC71BM) as an acceptor in binary blended thin films and vanadyl 3,10,17,24-tetra-tert-butyl-1,8,15,22-tetrakis(dimethylamino)-29H,31H-phthalocyanine (VTP) as a complementary holes’ component in ternary blended thin films. The combination of these materials creates favorable energy levels that facilitates the transport of charge carriers from one material to another until it reaches at the respective electrodes. The increase in optical absorption across broader spectral range, the increase in interfacial area and the enhancement in electrical parameters were observed and discussed. In this study, device with ternary P3HT:PC71BM:VTP blended thin films with ratio of 1:1:1 shown the best photo-current response (at 1 V), in which the increase in short-circuit photocurrent density (Jsc) (6.0 mA/cm2) is 78% higher than that of P3HT:PC71BM:VTP with ratio of 1:1:2. The Jsc of ternary blended thin film device (1:1:1) is 5 times higher than that of single material device and it appeared to be 58% higher than that of binary P3HT:PC71BM devices. The increase electrical parameters indicated a significant enhancement in photo-current with the introduction of ternary blended thin films organic photodetector that constitutes of well-matched materials based on their individual optical, morphological and electrical properties.
关键词： ternary blend,Organic photodetector,small molecule
更新于2025-09-19 17:13:59
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Monolithic Plasmonic Waveguide Architecture for Passive and Active Optical Circuits
摘要： Guided-wave plasmonic circuits are promising platforms sensing, interconnection, and quantum applications in the subdiffraction regime. Nonetheless, the loss-confinement trade-off remains a collective bottleneck for plasmonic-enhanced optical processes. Here, we report a unique plasmonic waveguide architecture that can alleviate such trade-off and improve the efficiencies of plasmonic-based emission, light-matter-interaction, and detection simultaneously. Specifically, record experimental attributes such as normalized Purcell factor approaching 104, 10 dB amplitude modulation with <1 dB insertion loss and fJ-level switching energy, and photodetection sensitivity and internal quantum efficiency of ?54 dBm and 6.4% respectively have been realized within our amorphous-based, coupled-mode plasmonic structure. The ability to support multiple optoelectronic phenomena while providing performance gains over existing plasmonic and dielectric counterparts offers a clear path toward reconfigurable, monolithic plasmonic circuits.
关键词： plasmonics,epsilon-near-zero,field-effect modulator,Purcell factor,Schottky photodetector
更新于2025-09-19 17:13:59
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Enhancing Small-Molecule Organic Photodetector Performance for Reflectance-Mode Photoplethysmography Sensor Applications
摘要： Organic photodetector performance for enhancing the sensing abilities of an organic photoplethysmography sensor was investigated. Optimized organic photodetector with an anode interlayer and a cathode interlayer showed reverse dark current density of 22 nA cm-2 at ?2 V and the external quantum efficiency of 53.3% at 0 V. This organic photodetector was fabricated monolithically with an organic light emitting diode on a glass substrate to achieve a reflectance-mode photoplethysmography sensor, demonstrating the impact of organic photodetector device performance on the measured photoplethysmography signal for sensing applications. Furthermore, we estimated the optimal sensor design for circular geometry in terms of device area and distance between organic light emitting diode and organic photodetector to maximize the signal-noise ratio and lower the power consumption of organic photoplethysmography sensor devices. For most favorable photoplethysmography sensor design, signal strength of 130 mV with 600 μW power consumption was measured.
关键词： detectivity,Organic photodetector,OLED,Interlayer,dark current density,signal to noise ratio (SNR),PPG Sensor
更新于2025-09-19 17:13:59
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High-Performance Free-Standing Flexible Photodetectors Based on Sulfur-Hyperdoped Ultrathin Silicon
摘要： Flexible photodetectors (PDs) prepared with silicon-based materials have received considerable attention for use in a wide range of portable and wearable applications. In this study, we present the first free-standing flexible PD based on sulfur-hyperdoped ultrathin silicon, which was fabricated using a femtosecond laser in SF6 atmosphere. It is found that the fabricated device exhibits excellent performance of broadband photoresponse from 400 to 1200 nm, with peak responsivity of 63.79 A/W @ 870 nm at a low bias voltage of -2 V, corresponding to an external quantum efficiency reaching 9092%, which surpasses most values reported for silicon-based flexible PDs. In addition, the device shows a fast response speed (rise time τr=68 μs) and stable detection performance with good mechanical flexibility. The high-performance PD described here suggests a promising way in flexible applications for sensors, imaging systems, and optical communication systems.
关键词： flexible photodetector,ultrathin silicon,black silicon,sulfur-hyperdoped,femtosecond laser
更新于2025-09-19 17:13:59
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A comparative study of organic photodetectors based on P3HT and PTB7 polymers for Visible Light Communication
摘要： Visible light communication (VLC) is a promising candidate to face the bandwidth limitation problems of traditional radio communication system. The use of a light emitting diode (LED), directly modulated, as a transmitter of the wireless telecommunication link permits the installation of VLC-based systems in practically all human-attended settings (home, office, markets). However, a drawback of VLC systems remains the receiver side, due to the lack of photovoltaic devices for this specific application. Organic electronics based on solution processed technologies has the great potential to be applied in VLC systems, building effective, scalable and low-cost photodetectors. We have investigated the effect of the device architecture on optical and electrical device performance, using both P3HT:PCBM and PTB7:PC70BM bulk-heterojunction active layers. We have established that both materials and structures could affect greatly the device properties, and we have provided an analytical representation of the spectral matching between light source and detector. In particular, the most promising device, based on a P3HT:PCBM blend, has demonstrated high performance, especially using an inverted structure. In this configuration, a device cut-off frequency of ~1.0MHz has been achieved, paying the way to organic photodetector application on VLC-based telecommunication systems in 5G scenarios.
关键词： 5G,organic photodetector,visible light communication,inverted architecture,bandwidth
更新于2025-09-19 17:13:59
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Photogating WS <sub/>2</sub> Photodetectors Using Embedded WSe <sub/>2</sub> Charge Puddles
摘要： Performance of 2D photodetectors is often predominated by charge traps that offer an effective photogating effect. The device features an ultrahigh gain and responsivity, but at the cost of a retarded temporal response due to the nature of long-lived trap states. In this work, we devise a gain mechanism, which originates from massive charge puddles formed in the type-II 2D lateral heterostructures. This concept is demonstrated using graphene-contacted WS2 photodetectors embedded with WSe2 nanodots. Upon light illumination, photoexcited carriers are separated by the built-in field at the WSe2/WS2 heterojunctions (HJs), with holes trapped in the WSe2 nanodots. The resulting WSe2 hole puddles provide a photoconductive gain, as electrons are recirculating during the lifetime of holes that remain trapped in the puddles. The WSe2/WS2 HJ photodetectors exhibit a responsivity of 3 × 102 A/W with a gain of 7 × 102 electrons per photon. Meanwhile, the zero-gate response time is reduced by 5 orders of magnitude as compared to the prior reports for the graphene-contacted pristine WS2 monolayer and WS2/MoS2 hetero-bilayer photodetectors due to the ultrafast intralayer excitonic dynamics in the WSe2/WS2 HJs.
关键词： WS2,2D material,photogating,photodetector,heterostructure,TMD
更新于2025-09-19 17:13:59