- 标题
- 摘要
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- 实验方案
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TiO2/SnO2 and SnO2/TiO2 heterostructures as photocatalysts for degradation of stearic acid and methylene blue under UV irradiation
摘要： The effect TiO2/SnO2 (TiO2 is on the top and SnO2 at the bottom) and SnO2/TiO2 (SnO2 is on the top and TiO2 at the bottom) heterostructures towards photocatalytic degradation of stearic acid and methylene blue is reported. The two heterostructures, wherein SnO2 (or TiO2) is the top or bottom layer, are prepared by the sol-gel technique. TiO2/SnO2 film exhibit better photocatalytic activity as compared to SnO2/TiO2, TiO2 and SnO2 films. Wettability studies reveal that TiO2/SnO2 films modified with stearic acid (8mM concentration of stearic acid in ethyl alcohol) tend towards superhydrophobic regime with contact angle as high as 137o. Further, TiO2/SnO2 films are efficient in degrading the stearic acid under UV irradiation. Interestingly, TiO2/SnO2 films that display flake like structures, with increased charge separation, are responsible for better degradation of pollutants under UV irradiation because of coupling heterostructures.
关键词： Bilayer film,Wettability,Superhydrophobic,Photocatalytic activity
更新于2025-11-19 16:56:35
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A systematic approach to ZnO nanoparticle-assisted electron transport bilayer for high efficiency and stable perovskite solar cells
摘要： Minimizing the interface loss of perovskite solar cells is critical to achieving high photovoltaic performance, and intensive research is underway on interfacial engineering in this regard. In this work, we introduce a ZnO nanoparticles (ZnO NPs) interlayer between phenyl-C61-butyric acid methyl ester (PCBM) and a metal electrode in order to reduce the interface loss due to charge recombination and device degradation, and also investigate the dependence of device performance on the thickness and morphology of the PCBM and PCBM/ZnO electron transport bilayer. After achieving optimized PCBM and ZnO thickness, the PCBM/ZnO bilayer-based devices reached an average power conversion efficiency of 15.63% (Max. 16.39%) with an open circuit voltage of 1.05 V, short circuit current density of 18.69 mA cm-2, and fill factor of 79.95%. In addition, hysteresis behavior and atmospheric stability are significantly improved by the incorporation of a PCBM/ZnO bilayer. Therefore, the implementation of a PCBM/ZnO electron transport bilayer is a promising approach toward achieving a high-efficiency PSC with stable power output (low J-V hysteresis) and durability.
关键词： ZnO nanoparticles,interfacial engineering,stable perovskite solar cells,interface loss,high-efficiency perovskite solar cells,electron transport bilayer
更新于2025-11-19 16:46:39
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High Efficiency Non‐Doped White Organic Light Emitting Diodes Based on a Bilayer Interface‐Exciplex Structure
摘要： High efficiency non-doped blue and white organic light emitting diodes (OLEDs) are realized by using a bilayer interface-exciplex (i-Exc) structure. Since the neutral exciplex are formed at the interface, the interface charge accumulation is reduced, thereby suppressing exciton quenching in the device. With the i-Exc structure, a maximum external quantum efficiency (EQE) of 23.1% is achieved in the non-doped blue phosphorescent OLED. Moreover, the white emission can be obtained by inserting an ultrathin orange-red phosphorescent emitter into the blue devices. The charge trapping in the orange-red emitter can be suppressed by adjusting the position of the ultrathin orange-red emitting layer in the device, contributing to superior spectral stability. The WOLED achieves an EQE of 20.0% and exhibits a stable warm white emission. The Commission Internationale de l’Eclairage (CIE) coordinates of WOLED are (0.41, 0.40) at 5 V and slightly change to (0.40, 0.41) at 9 V.
关键词： interface-exciplex,PHOLED,WOLED,bilayer structure,ultrathin non-doped emitting layers
更新于2025-11-14 15:26:12
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Preparation and measurement of subwavelength bilayer metal wire grid polarizers on flexible plastic substrates
摘要： This paper presents a process for the fabrication of subwavelength bilayer metal wire grid polarizers and describes the performance characterization of polarizers that were produced using the proposed method. These polarizers have a period of 278 nm and were fabricated on flexible plastic substrates using nanoimprint lithography followed by an aluminum deposition process. Transmission efficiency in excess of 0.55 and an extinction ratio of more than 32 dB were achieved in the visible range when the aluminum layer thickness of the polarizer was 70 nm. When a polarization analyzer with a six-channel sensor prototype was tested, an average error of 0.2002? was obtained, with a maximum error of 1.105? and a standard deviation of 0.7255?. The proposed fabrication method will be suitable for many applications in optics, including the manufacture of compound eye structures.
关键词： Extinction ratio,TM transmission,Nanoimprint lithography,Bilayer metal wire-grid polarizers
更新于2025-09-23 15:23:52
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Fabrication of bilayered attapulgite for solar steam generation with high conversion efficiency
摘要： Solar steam generation has been attracting wide attention for boosting the evolution of solar-energy-harvesting technology. Here, we demonstrate the fabrication of a novel bilayer photothermal material based on attapulgite/poly acrylamide composite (APAC), which was prepared by the solution polymerization of acrylamide (AM) in the presence of attapulgite using N, N’ - Methylene bisacrylamide (MBA) as a crosslinker, for efficient solar steam generation. The APAC shows better thermal stability with a decomposition temperature of 250 oC, good mechanical property with a compress strength of up to 125 KPa at 75% strain and a low apparent density (0.0191 g·cm-3) with abundant porosity accompanying with a low thermal conductivity (0.07 W m-1 K-1). To enhance the light absorption of APAC, a thin carbon layer was created on the surface of APAC via a facile flame treatment. Under our conditions, the bilayered APAC shows a high vapor rate of 1.2 kg m-2 h-1 under 1 sun illumination, equal to 85% solar-to-vapor efficiency. With the merits of cost-efficient, scalable manufacture, high solar energy conversion efficiency, the APAC may hold the great potential as high-performance photothermal materials for solar energy generation.
关键词： conversion efficiency,Solar steam generation,attapulgite,bilayer
更新于2025-09-23 15:23:52
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Optical response of a bilayer crystal
摘要： We extend the recently developed classical theory for the optical response of a single-layer crystal to bilayers. We account for the interaction between the two atomic planes and the multiple reflections inside the crystals. We show how to define a global susceptibility meaningful for the bilayer crystal and how its expression varies compared to the single-layer case. We compute both the local and the macroscopic fields, which allow us to make a direct comparison with experimental data.
关键词： local fields,bilayer crystal,optical response,susceptibility,macroscopic fields
更新于2025-09-23 15:23:52
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Hybrid bilayer gate dielectric-based organic thin film transistors
摘要： Organic thin film transistors (OTFTs) are key building blocks for flexible, low cost electronics systems. They provide a viable alternative for silicon-based electronics with added advantages of low cost and flexibility. However, few issues like high-operating voltage, low-switching speed, high-leakage current and reliability are still a challenge. The overall performance of an OTFT depends on organic semiconductors and gate dielectric interface. In this paper, we review the current status and trends in the choice of dielectric layer for OTFTs. As a starting point, the performance parameters of an OTFT and their dependence on the dielectric layer are briefly discussed. A variety of dielectric materials which includes high-k inorganic, organic, surface coated inorganics and nanocomposites are also presented. The advantages and drawbacks of each of these materials are discussed in detail. We reviewed the latest developments in the dielectric materials especially, self-assembled monolayers (SAMs), hybrid bilayers and nanocomposites. SAM-based OTFTs offer several advantages but shift in the threshold voltage remains a concern. Nanocomposites are a latest addition to the dielectric materials, which offer advantages like solution processing and improved dielectric constant but have a rough surface. A hybrid bilayer that incorporates the inorganic dielectric as a base layer and a thin polymer layer over it to improve the surface properties offers several desirable characteristics over the other choices. Hence, we propose that hybrid bilayer gate dielectrics shall play a pivotal role in improving the OTFT performance.
关键词： low-k organic,high-k inorganic,Organic thin film transistor,self-assembled monolayer,gate dielectric,hybrid bilayer
更新于2025-09-23 15:23:52
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - A cost-effective and high performance assembly technology for interconnecting the Cu/Al bilayer electrode and lead wire of ZnO varistor using a low Ag-containing solder paste
摘要： In this paper, the spreading ability of solder pastes with different Ag contents on Ag and Cu/Al bilayer electrodes was investigated in detail. The mechanical performance (i.e., stripping force) and microstructure of 'lead-wire/solder/electrode/ZnO' joints were characterized. The electrical property of ZnO varistors soldered by various solder pastes was also analysed. Results show that the low Ag-containing solder paste with the assistance of the flux having appropriate activity exhibits similar spreading ability on Ag and Cu/Al bilayer electrodes with the high Ag-containing solder paste. Moreover, the difference in Ag content of solder pastes has little influence on the stripping force of the solder joints and the surge performance of ZnO varistors. High activity of the solder paste may lead to severe corrosion of Ag electrode and decrease in the stripping force of the joints, and low activity of the solder paste brings the problem of inadequate removal of oxide films on the Cu/Al bilayer electrode, which leads to poor soldering quality and lower stripping force of the joints. ZnO varistors with Cu/Al bilayer electrodes have superior surge performance over those with Ag electrodes.
关键词： Cu/Al bilayer electrode,ZnO varistor,mechanical performance,spreading ability,low Ag-containing solder paste
更新于2025-09-23 15:22:29
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Multiple topological transitions in twisted bilayer graphene near the first magic angle
摘要： Recent experiments have observed strongly correlated physics in twisted bilayer graphene (TBG) at very small angles, along with nearly flat electron bands at certain fillings. A good starting point in understanding the physics is a continuum model (CM) proposed by Lopes dos Santos et al. [Phys. Rev. Lett. 99, 256802 (2007)] and Bistritzer et al. [Proc. Natl. Acad. Sci. USA 108, 12233 (2011)] for TBG at small twist angles, which successfully predicts the bandwidth reduction of the middle two bands of TBG near the first magic angle θ0 = 1.05°. In this paper, we analyze the symmetries of the CM and investigate the low energy flat band structure in the entire moiré Brillouin zone near θ0. Instead of observing flat bands at only one 'magic' angle, we notice that the bands remain almost flat within a small range around θ0, where multiple topological transitions occur. The topological transitions are caused by the creation and annihilation of Dirac points at either K, K', or Γ points or along the high symmetry lines in the moiré Brillouin zone. We trace the evolution of the Dirac points, which are very sensitive to the twist angle, and find that there are several processes transporting Dirac points from Γ to K and K'. At the Γ point, the lowest energy levels of the CM are doubly degenerate for some range of twisting angle around θ0, suggesting that the physics is not described by any two-band model. Based on this observation, we propose an effective six-band model (up to second order in quasimomentum) near the Γ point with the full symmetries of the CM, which we argue is the minimal model that explains the motion of the Dirac points around Γ as the twist angle is varied. By fitting the coefficients from the numerical results, we show that this six-band model captures the important physics over a wide range of angles near the first 'magic' angle.
关键词： flat bands,twisted bilayer graphene,continuum model,magic angle,topological transitions,Dirac points
更新于2025-09-23 15:22:29
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Improvement of Conversion Loss of Resistive Mixers Using Bernal-stacked Bilayer Graphene
摘要： In this letter, we present dual-gate Bernal-stacked bilayer graphene FETs which are used for gate-pumped resistive mixers. The results show that conversion loss improves when the device on/off ratio increases. At 2 GHz, a record conversion loss of 12.7 dB has been obtained from 160 nm device among graphene resistive mixers. Furthermore, more than 10 dB change of conversion loss has been obtained by adjusting the electric displacement field by dual-gate voltage. Finally, high-temperature characteristics of this type of graphene mixer exhibit excellent thermal stability with only 2 dB degradation in conversion loss from 300 to 380 K. This result shows the Bernal-stacked bilayer graphene mixer is promising for low-loss and high-temperature radio frequency circuit applications.
关键词： conversion loss,high temperature,bilayer graphene,resistive mixer,FETs
更新于2025-09-23 15:22:29