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Fine Fabrication and Optical Waveguide Characteristics of Hexagonal tris(8-hydroxyquinoline)aluminum(a?￠) (Alq3) Crystal
摘要： Herein, we reported on the precise growth and optical waveguide characteristics of hexagonal tris(8-hydroxyquinoline)aluminum(III) (Alq3) micro-crystals (MCs). The hexagonal Alq3 MCs were prepared using surfactant-assisted assembly growth with the help of cetyltrimethylammoniumbromide (CTAB), in which the crystallization occurred as a result of molecular assembly and packing. Also, we adjusted the molar ratio of Alq3 and CTAB for the control degree of crystallization. The formation and structure of Alq3 MCs were investigated using field-emission scanning electron microscopy and X-ray diffraction pattern experiments, respectively. The solid-state laser confocal microscope-photoluminescence spectra and charge-coupled device images for the Alq3 MCs were measured to study the luminescence efficiency and colors, respectively. The optical waveguide performance of the hexagonal Alq3 MCs was measured for each side direction. According to our results, crystalline Alq3 micro-crystals are promising materials for application to the development of optical communication devices.
关键词： photoluminescence,crystallinity,organometal,surfactant,Alq3,confocal microscope,waveguide
更新于2025-11-21 11:24:58
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One-step synthesis of centimeter-size alpha-MoO3 with single crystallinity
摘要： By utilizing the convenient physical vapor deposition procedure, a simple and low-cost synthesis route is developed to fabricate high-quality orthorhombic MoO3 crystals with single crystallinity and significant size (bigger than 10mm×10 mm2). A combined characterization techniques of atomic force microscopy, X-ray photoelectron spectroscopy, synchrotron-based X-ray diffraction and Raman spectroscopy confirm the high quality of α-MoO3 crystal from the point view of both electronic and physical structures. Compared to previous reports in literature, we demonstrate herein a rather simplified one-step approach with only the MoO3 powder needed. In the end, corresponding electrochromic performance has also been been tested which reveals high transmittance and remarkable optical properties which may broadens the potential applications of MoO3 single crystal in nanosensors, nanoelectronics and so on.
关键词： GIXRD,XPS,single crystallinity,Physical Vapor Deposition,α-MoO3
更新于2025-11-21 11:24:58
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Morphology Phase Diagram of Slot‐Die Printed TiO <sub/>2</sub> Films Based on Sol–Gel Synthesis
摘要： Mesoporous titania films with tailored nanostructures are fabricated via slot-die printing, which is a simple and cost-effective thin-film deposition technique with the possibility of a large-scale manufacturing. Based on this technique, which is favorable in industry, TiO2 films possess the similar advantage with polymer semiconducting devices like ease of large-scale production. The titania morphologies, including foam-like nanostructures, nanowire aggregates, collapsed vesicles and nanogranules, are achieved via a so-called block-copolymer-assisted sol–gel synthesis. By adjusting the weight fraction of reactants, the ternary morphology phase diagram of the printed titania films is probed after template removal. The surface and inner morphology evolutions are explored with scanning electron microscopy and grazing incidence small-angle X-ray scattering, respectively. Special focus is set on foam-like titania nanostructures as they are of especial interest for, e.g., solar cell applications. At a low weight fraction of the titania precursor titanium(IV)isopropoxide (TTIP), foam-like titania films are achieved, which exhibit a high uniformity and possess large pore sizes. The anatase phase of the highly crystalline titania films is verified with X-ray diffraction and transmission electron microscopy.
关键词： TiO2 films,crystallinity,morphology phase diagram,printing,GISAXS
更新于2025-11-21 11:20:42
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Effect of processing conditions on additive DISC patterning of P3HT films
摘要： There is a critical need to develop a method to pattern semiconducting polymers for device applications on the sub-micrometer scale. Dopant induced solubility control (DISC) patterning is a recently published method for patterning semiconductor polymers that has demonstrated sub-micron resolution. DISC relies on the sequential addition of molecular dopants (here 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ)) to the conjugated polymer. In doped areas, the conjugated polymer is protected from dissolution while in undoped areas, the polymer dissolves into solution. Here we examine factors that affect the resolution of the developed pattern. Two factors are determined to be critical to pattern resolution, the initial crystallinity of the polymer, here poly(3-hexylthiophene) (P3HT), and the quality of the development solvent. We find that dopants diffuse more readily in highly crystalline films than in amorphous films of P3HT and that dopant diffusion reduces the fidelity of the resulting pattern. We also find that the choice of development solvent affects both the fidelity of the pattern and dopant distribution within the patterned polymer domains. Finally, we show that a dopant that diffuses more slowly than F4TCNQ in the P3HT film can be used to pattern the film with higher fidelity. These results together provide a road map for optimizing additive DISC patterning for any polymer/dopant pair.
关键词： crystallinity,semiconducting polymers,development solvent,pattern fidelity,P3HT,DISC patterning,F4TCNQ
更新于2025-11-21 11:08:12
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Role of chamber pressure on crystallinity and composition of silicon films using silane and methane as precursors in hot-wire chemical vapour deposition technique
摘要： Hot-wire chemical vapour deposition is a versatile technique to deposit a-Si:H and nc-Si films at higher deposition rate (~5-10 ?/sec) as compared to Plasma enhanced chemical vapour deposition (1-2 ?/sec). We report the deposition of highly crystalline Si films at very high deposition rate (≥ 40?/sec) by adding methane to silane during thermal/catalytic decomposition. A series of films were deposited by varying the chamber pressure between 10-100 Pa at a substrate temperature of 300 °C and filament temperature 2000 °C. The hydrogen diluted silane (10% silane in hydrogen) and pure methane were used as precursors and gas flow rate ratio was kept constant at 10. Films prepared at lower pressure (≤ 20 Pa) were more crystalline and do not contain any trace of carbon atoms. Bandgap was found to increase from 1.24-1.63 eV when pressure was increased. It was observed that chamber pressure plays a key role in determining the crystallinity, disorder and composition of these films. Addition of methane to hydrogen diluted silane increased deposition rate and crystallinity of Si films at low pressure (≤ 20 Pa). Above 20 Pa pressure, carbon atoms signature was obtained. SiC films were obtained when pressure was > 100 Pa.
关键词： Deposition rate,Si films,Crystallinity,Hot-wire chemical vapour deposition
更新于2025-11-21 11:01:37
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Improve the crystallinity and morphology of perovskite films by suppressing the formation of intermediate phase of CH3NH3PbCl3
摘要： Crystallinity and morphology of perovskite films can greatly influence the performance of perovskite solar cells (Pero-SCs) in terms of charge carrier generation and transportation. Incorporation of Cl (from either PbCl2 or CH3NH3Cl) in crystal growth of CH3NH3PbI3 is known as an effective method to acquire larger crystal grains and longer carrier diffusion length. It has been reported that an intermediate phase of CH3NH3PbCl3 was usually observed during crystallization, which should be critical to the quality of the resulting perovskite, however, how the intermediate phase influence the crystal growth was lack of comprehensive understanding. In this study, through varying the mixing ratio of the precursors PbI2:2CH3NH3I and PbCl2:3CH3NH3I, we were able to systematically tune the content and the converting time of CH3NH3PbCl3. We found that suppressing the formation of CH3NH3PbCl3 within the as-cast films can effectively improve the quality (crystallinity and morphology) of the resulting perovskite films. The improvement led to significant enhancement of the performance of the corresponding p-i-n planar Pero-SCs. Under optimized conditions, the best PCE was increased from 12.8% to 16.2%, which should be attributed to the alleviated charge recombination due to the improved quality of perovskite films by suppressing the formation of CH3NH3PbCl3.
关键词： morphology and crystallinity,perovskite solar cells,CH3NH3PbCl3,intermediate phase,charge recombination
更新于2025-11-14 15:13:28
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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Investigation of the Phase Composition and Morphology of Silicon Structures by Using the Raman Spectroscopy to Determine the Parameter of Crystallinity
摘要： This work aims to investigate the dependence of the phase composition of thin films of microcrystalline silicon deposition on process parameters. The films of microcrystalline silicon were obtained by plasma-chemical deposition method (PECVD). Phase composition and correlation between degree of crystallinity and structure of the obtained layers were analyzed by Raman Spectroscopy. The results show that the control of several technical parameters, e.g. pressure, discharge power and monosilane flow, allows to reach the crystallinity parameter in the range 50-70 %. Based on the conducted experiments, the recommendations for the control of the crystallinity parameter, which are planned to be implemented when working with silicon-based porous structures, were proposed.
关键词： Morphology,Semiconductors,Silicon,Por-silicon,Phase composition,Raman spectroscopy,Raman Crystallinity
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Features of Space Charge Relaxation in a Polyimide Printed Circuit Board
摘要： Polyimide films are widely used as substrates for printed circuit boards. The process of space charge accumulating in dielectric substrates is not highly desirable, since space charge distorted the parameters of the electrical circuits. This work is devoted to the study of the accumulation and relaxation of charge in films of thermoplastic polyimide R-BAPB with different degrees of crystallinity, in order to reduce the accumulated charge and the time of its relaxation. Relaxation mechanisms are analyzed and methods for reducing the relaxation time of the space charge are determined.
关键词： PCB,conductivity,electret,homocharge,relaxation,corona discharge,space charge,crystallinity,polyimide
更新于2025-09-23 15:22:29
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Tailor-made ultra-crystalline, high molecular weight poly(ε-caprolactone) films with improved oxygen gas barrier and optical properties: a facile and scalable approach
摘要： The work presents a facile and scalable approach for fabricating tailor-made ultra-crystalline, high molecular weight biodegradable polymer poly(ε-caprolactone) [PCL] through ring-opening polymerization. Linear homopolymer of PCL were fabricated by tuning the molar ratio of monomer: initiator: catalyst in associated with organometallic catalyst (tin octoate) and a non-toxic and structurally symmetric initiator ethylene glycol (EG). High molecular weight PCL homopolymer formation with molecular weight higher than 90000 Da was examined by FTIR, NMR and GPC. The ultra-crystalline characteristics (percent crystallinity, %Xc >70%) and unique crystal morphology of PCL were thoroughly scrutinized using DSC, XRD, HRTEM, SAED patterns and POM analysis. The developed protocol for the solvent-free technology allows high conversion ~99% at lowest possible reaction time of 1 h suggesting it a cost effective process, which is scalable to larger volume (5000 mL) without compromising the final product properties. The fabricated ultra-crystalline, high molecular weight PCL films showed good oxygen barrier property (~ 197 cm3 mm-1 day-1), surface free energy (133.7 mN/m) and optical transparency, recommending its niche in envisioned applications like low temperature flexible packaging and biomedical field.
关键词： Poly(ε-caprolactone) [PCL],Crystallinity,Oxygen barrier property
更新于2025-09-23 15:21:21
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Increasing Membrane Permeability by Increasing the Polymer Crystallinity: The Unique Case of Polythiophenes
摘要： It is generally accepted in membrane technology that crystalline zones in polymeric membranes do not contribute to transport of liquids or gases. In the current study, poly(3-alkylthiophene)s (P3ATs), i.e., homopolymers and random copolymers, were synthesized to study the influence of the supramolecular organization on membrane gas separations. The monomers were polymerized via KCTCP, and GPC analysis shows that the polymers have a narrow dispersity. DSC analysis of the polymers reveals that the homopolymers, in contrast to the copolymers, crystallized, confirming their higher degree of supramolecular organization. This was supported by UV?vis absorption spectra of the polymer films, where a red-shift and a characteristic shoulder absorption peak around 600 nm were observed for the homopolymers, while absent for the copolymers. More surprisingly, the homopolymers were found to be 2 orders of magnitude more permeable to CO2 than the copolymers and also more selective.
关键词： selectivity,gas separations,permeability,membrane technology,supramolecular organization,poly(3-alkylthiophene)s,crystallinity
更新于2025-09-23 15:21:21