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Effect of Annealing Treatment on Optical and Electrical Properties of PCDTBT:Graphene Hybrid Structure for Photovoltaic Application
摘要： Indium tin oxide (ITO)/poly[N-9￠-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2￠,1￠,3￠-benzothiadiazole)] (PCDTBT):graphene/Al structures have been elaborated. By applying a specific elaboration method, we succeeded in dispersing expandable graphene oxide in organic solvent (N,N-dimethylformamide, DMF) to obtain graphene oxide and insert it into a PCDTBT matrix. The effect of annealing treatment of PCDTBT:graphene films on the optical and electrical properties were studied. The obtained results showed a remarkable effect of the annealing treatment on the optoelectronic properties. The ultraviolet–visible (UV–Vis) spectra showed that the light harvesting was increased and the orderly stacking of the polymer chains was enhanced. The photoluminescence results showed a red-shift of about 10 nm in case of heat treatment at 150°C, related to an increase of the conjugation length of the polymer chains. The electrical parameters, such as the series resistance (Rs), ideality factor (n), and barrier height (/b), were calculated. We found that thermal annealing reduced both the series resistance Rs and barrier height value /b, significantly. These results indicate that annealing treatment improves the transport phenomenon in the active layer. In addition, the Log(J)–Log(V) curves suggested that the charge transport is governed by a space-charge-limited mechanism current. The effective carrier mobility (leff) was on the order of 10?5 cm2/V.
关键词： annealing treatment,hybrid structure,PCDTBT,graphene oxide,bulk heterojunction,Nanocomposite
更新于2025-09-11 14:15:04
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Improved disinfection performance towards human adenoviruses using an efficient metal-free heterojunction in a vis-LED photocatalytic membrane reactor: Operation analysis and optimization
摘要： Waterborne human viruses, with ubiquitous prevalence in aquatic environments, extremely low infectious doses, and high resistance to common disinfection processes, pose a substantial threat to human health. Herein, for the first time, a photocatalytic membrane reactor (PMR) driven by visible light emitting diodes (Vis-LEDs) was applied for effective water disinfection of human adenoviruses. The photocatalyst used in the PMR was selected to be a metal-free heterojunction (named as CNO) with the advantages of visible-light-response, efficient virucidal effects, green properties and easy recovery via microfiltration. The disinfection performance of the Vis-LED PMR towards human adenoviruses was improved by adjusting operation with response surface methodology (RSM). Based on twenty sets of operating data, a semi-empirical model was established with a high accuracy of R2 = 0.9622 for predicting the final adenovirus inactivation after 300-min operation. The optimal operating solution was found to be 5.00-log MPN/mL, 320.30 mg/L and 502.65 min for initial virus concentration (IVC), photocatalyst loading (PL) and hydraulic retention time (HRT), respectively. Under the optimized operation, all human adenoviruses were completely inactivated without regrowth, accompanied by severe damage to capsids, within 600 min in the Vis-LED PMR. In addition, the CNO photocatalyst could be retained inside the reactor via low-energy microfiltration with excellent recovery (99.9 wt%) but without obvious chemical or structural changes. Our work can offer a simple, effective, economical and eco-friendly water disinfection device against resistant pathogenic microbes, with controllable efficiency by facilely varying operating solutions.
关键词： operation analysis,photocatalytic membrane reactor,Vis-LED,metal-free heterojunction,human adenoviruses,optimization
更新于2025-09-11 14:15:04
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Photodetector based on heterostructure of two-dimensional WSe2/In2Se3
摘要： Heterojunctions formed by two-dimensional (2D) layered semiconducting materials have been studied extensively in the past several years. These van der Waals (vdW) structures have shown great potential in future electronic and optoelectronic devices. However, the optoelectronic performance of these devices is limited by the indirect band gap of the multilayer materials and low light absorption of single layer materials. Here, we fabricate photodetectors based on heterojunctions composed of n-type multilayer α-Indium Selenide (In2Se3) and p-type Tungsten Diselenide (WSe2) for the first time. The direct band gap of multilayer α-In2Se3 and type-II band alignment of the WSe2/In2Se3 heterojunction enable high optoelectronic performance of the devices at room temperature in the air. Without light illumination, the dark current is effectively suppressed to 10-13 A under -1 V bias and a high rectification ratio of 7.37×103 is observed. Upon laser illumination with the wavelength of 650 nm, the typical heterojunction device exhibits a photocurrent on/off ratio exceeding 1.24×105, a maximum photo responsivity of 26 mA/W and short photoresponse time of 2.22 ms. Moreover, the heterojunction photodetectors show obvious light response in the wavelength range from 650 nm to 900 nm. The present 2D vdW heterojunctions composed of direct band gap multilayer materials show great potential in future optoelectronic devices.
关键词： In2Se3,photodetector,two-dimensional materials,WSe2,direct band gap materials,heterojunction
更新于2025-09-11 14:15:04
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Solution-Processed Phototransistors Combining Organic Absorber and Charge Transporting Oxide for Visible to Infrared Light Detection
摘要： This report demonstrates high-performance infrared phototransistors that uses a broadband absorbing organic bulk heterojunction (BHJ) layer responsive from the visible to the shortwave infrared, from 500 nm to 1400 nm. The device structure is based on a bilayer transistor channel that decouples charge photogeneration and transport, enabling independent optimization of each process. The organic BHJ layer is improved by incorporating camphor, a highly polarizable additive that increases carrier lifetime. An indium zinc oxide transport layer with high electron mobility is employed for rapid charge transport. As a result, the phototransistors achieve a dynamic range of 127 dB and reach a specific detectivity of 5×1012 Jones under low power illumination of 20 nW/cm2, outperforming commercial germanium photodiodes in the spectral range below 1300 nm. The photodetector metrics are measured with respect to the applied voltage, incident light power, and temporal bandwidth, demonstrating operation at the video-frame rate of 50 Hz. In particular, the frequency and light dependence of the phototransistor characteristics are analyzed to understand the change in photoconductive gain under different working conditions.
关键词： shortwave infrared,phototransistor,indium zinc oxide,bulk heterojunction,carrier lifetime,semiconducting polymer,camphor
更新于2025-09-11 14:15:04
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Interfacial properties of Hg <sub/>2</sub> CuTi-type Heusler alloy Ti <sub/>2</sub> NiAl/GaAs(100) heterojunction
摘要： For Hg2CuTi-type Inverse-Heusler alloy Ti2NiAl/GaAs(100) tunnel heterojunction, the magnetism, density of states and spin polarization of atoms at the interface were investigated systematically based on the first-principle calculation within the density functional theory (DFT). The calculated results reveal that the interface states seriously destroy the structural half-metallicity and lead to the spin polarization less than 60%. Among all of calculational hetero-structures, only the heterojunction with TA-ATⅡ structure still retains nearly 60% spin polarization, which is expected for further application in Tunnel Magneto resistance (TMR) devices.
关键词： first-principle calculation,Hg2CuTi-type Heusler alloy,TMR devices,Ti2NiAl/GaAs(100) heterojunction,spin polarization
更新于2025-09-11 14:15:04
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In-situ fabrication of needle-shaped MIL-53(Fe) with 1T-MoS2 and study on its enhanced photocatalytic mechanism of ibuprofen
摘要： High photocatalytic hole-electron pairs separation efficiency and the wide use of inexpensive and earth-abundant materials as cocatalysts in most semiconductor-based photocatalytic systems are desired for improving the photocatalytic activity and practical application. Herein, we report a facile one-pot solvothermal approach of integrating stable metallic nonmetal materials 1T-MoS2 nanosheets with MIL-53(Fe) to form needle-shaped 1T-MoS2@MIL-53(Fe) (TSMF) composites. Interestingly, the introduction of 1T-MoS2 turns nonspecial-structured MIL-53 (Fe) into needle-like structure and the BET analysis reveals that the optimal TSMF composites possess abundant coexistence of micropores and mesopores with a large surface area of 337 m2g-1, which is about 16 folds higher than that of the pure MOFs. Meanwhile, it is remarkable that the photocatalytic rate of ibuprofen (IBP) by optimal TSMF nanocomposites has improved 7.5 and 9.4 times compared to the pristine MIL-53(Fe) and 1T-MoS2, respectively. The photocatalytic efficiency of TSMF composites enhances due to the emerging micropores, which can provide more adsorption and reaction sites. In addition, the formed compact and uniform interface contact between 1T-MoS2 sheets and MOF may dramatically accelerate the separation of the photo-induced charges, thus enhance the photocatalytic activity. We also study the photocatalytic mechanism combined the corresponding electrochemical testing and the photo-degradation intermediates identified by ion chromatography (IC) and LC-MS-MS, indicating that superoxide radicals (·O2-), hydroxyl radical (·OH) and electrons (e-) are the main active radicals in IBP photocatalysis and decarboxylation and hydroxylation are the main degradation pathways of IBP.
关键词： heterojunction structure,Visible light,MIL-53(Fe),ibuprofen,1T-MoS2
更新于2025-09-11 14:15:04
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Enhanced photocatalytic activity and stability of AgBr/BiOBr/graphene heterojunction for phenol degradation under visible light
摘要： In this work, we have reported synthesis of AgBr/BiOBr photocatalyst supported on graphene (Gr) using facile precipitation method. AgBr/BiOBr/Gr was characterized using various spectral techniques like FESEM, TEM, XRD, FTIR, XPS, Raman and PL analyses. AgBr/BiOBr/Gr had improved visible light absorption. PL studies indicated the reduction in recombination of photogenerated electron hole pair of AGBr/BiOBr/Gr. AFM analysis con?rmed the thickness of AGBr/BiOBr/Gr was less than 8.0 nm. The higher dispersibility of photocatalyst was ascertained by Tyndall effect. AgBr/BiOBr/Gr photocatalyst was effectively used for the photodegradation of phenol from simulated water. The phenol degradation process was remarkably in?uenced by adsorption process. The concurrent adsorption and photocatalytic was effective for degradation of phenol. The phenol was completely mineralized into CO2 and H2O in 6 h. The degradation process followed pseudo ?rst order kinetics. The results con?rmed that integration of AgBr/BiOBr with graphene caused an increase in photocatalytic activity due to reduced recombination of photogenerated electron hole pair and electron sink behavior of graphene for photogenerated electrons of BiOBr. AgBr/BiOBr/Gr photocatalyst displayed signi?cant stability and recyclability for ten catalytic cycles.
关键词： Enhanced photocatalytic activity,Recyclability,Phenol degradation,Graphene,AgBr/BiOBr,Heterojunction formation
更新于2025-09-11 14:15:04
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Cryogenic Characterization of RF Low-Noise Amplifiers Utilizing Inverse-Mode SiGe HBTs for Extreme Environment Applications
摘要： The cryogenic performance of radiation-hardened radio-frequency (RF) low-noise amplifiers (LNAs) is presented. The LNA, which was originally proposed for the mitigation of single-event transients (SETs) in a radiation environment, uses inverse-mode silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) in its core cascode stages. In this prototype, the upper common-base SiGe HBT is configured in inverse mode for balanced RF performance and reduced SET sensitivity. In order to better exploit the inverse-mode LNAs in a variety of extreme-environment applications, the RF performance of the LNA was characterized using liquid nitrogen to evaluate cryogenic operation down to 78 K. While the SiGe LNA exhibits acceptable RF performance for all temperature conditions, there is a noticeable gain drop observed at 78 K compared to the conventional forward-mode design. This is attributed to the limited high-frequency performance of an inverse-mode SiGe HBT. As a guideline, compensation techniques including layout modifications and profile optimization are discussed for the mitigation of the observed gain degradation.
关键词： low-noise amplifier (LNA),heterojunction bipolar transistor (HBT),cascode,inverse mode,extreme environment,cryogenic measurement,silicon-germanium (SiGe)
更新于2025-09-11 14:15:04
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Synthesis of Mesoporous TiO2/Boron-Doped Diamond Photocatalyst and Its Photocatalytic Activity under Deep UV Light (λ = 222 nm) Irradiation
摘要： There is a need for highly efficient photocatalysts, particularly for water purification. In this study, we fabricated a mesoporous TiO2 thin film on a boron-doped diamond (BDD) layer by a surfactant-assisted sol-gel method, in which self-assembled amphiphilic surfactant micelles were used as an organic template. Scanning electron microscopy revealed uniform mesopores, approximately 20 nm in diameter, that were hexagonally packed in the TiO2 thin film. Wide-angle X-ray diffraction and Raman spectroscopy clarified that the framework crystallized in the anatase phase. Current–voltage (I–V) measurements showed rectification features at the TiO2/BDD heterojunction, confirming that a p–n hetero-interface formed. The as-synthesized mesoporous TiO2/BDD worked well as a photocatalyst, even with a small volume of TiO2 (15 mm × 15 mm × c.a. 1.5 μm in thickness). The use of deep UV light (λ = 222 nm) as a light source was necessary to enhance photocatalytic activity, due to photo-excitation occurring in both BDD and TiO2.
关键词： photocatalyst,water purification,thin film,surfactant-assisted sol-gel method,p-n heterojunction,deep UV light,mesoporous metal oxide
更新于2025-09-10 09:29:36
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Analytical Study of Electron Mobility in Hemts Algan/Gan
摘要： The hetero junctions GaN based offer an excellent potential for power applications at high frequency. This is due to the important energy of the bandgap and high saturation velocity of electrons. The high mobility transistors (HEMT - High Electron Mobility Transistor) are based on the heterojunction AlGaN/GaN. Our work is the subject of an analytical study of the carrier mobility HEMTs AlGaN/GaN calculating Ionized impurities scattering, Residual impurities scattering, Interface roughness scattering, Alloy disorder scattering, dislocations scattering, Phonons and Dipoles taking into account the impact of technological parameters (doping, aluminium content) and geometric (thickness barrier, interface roughness). The results allowed us to take account of the variation of carrier density in the wells of 2D electronic gas.
关键词： HEMT,Mobility,Scattering mechanism,AlGaN/GaN heterojunction,2DEG
更新于2025-09-10 09:29:36