排序方式: 共有29条查询结果,搜索用时 109 毫秒
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《Organic Electronics》2014,15(2):622-630
Four star-shaped like fused heterocyclic compounds multi-electrochromic materials 2,4,6-Tri(pyridine-4-yl)pyridilium derivatives (TPPDs) were successfully synthesized and characterized by NMR, Solid IR spectra, APCI-MS, and UV–vis spectroscopy. The electrochemical properties, electrochromic behavior, electro-optical properties, and electrochromic mechanism were investigated by thermogravimetric analysis, cyclic voltammetry and UV–vis absorption spectra. Electrochromic devices based on these compounds were fabricated with an active area of 3 cm × 4 cm and their electrochromic performances were further studied. It was found the ECDs presented a stable as well as multicolor electrochromic change from colorless to blue, then violet-blue and finally black-blue between 0 V and +4.0 V. In addition, the prepared electrochromic materials had high coloration efficiency, low switching time, and nice redox stability. This type of multi-electrochromic materials would thus be promising candidates for applications in electrochromic devices. 相似文献
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《Ceramics International》2022,48(24):36201-36209
The persistent luminescence (PersL) materials Ca2Sb2O7:Pr3+ were prepared by traditional high-temperature solid-state method. We systematically investigated the crystal structure, band structure, photoluminescence, PersL performance by X-ray diffraction diagrams, Materials Studio calculation, photoluminescence (PL) spectra, PersL spectra and CIE coordinate analysis. The PL and PersL are attributed to the Sb5+ → O2? transition of the matrix and the 4f-4f transition of Pr3+ ion. For the sake of explaining the impact of various traps on PersL performance, thermoluminescence (TL) tests were performed on the optimal sample after diverse charging and discharging times. It was concluded that shallow traps have priority over deep traps in capturing electrons, and the electrons in the shallow traps were preferentially released. The highlight of this work is that the PL and PersL color can be adjusted by regulating the Pr3+ doping concentration when these samples were excited by a single excitation wavelength, so as to achieve a double anti-counterfeiting effect. Furthermore, the color change of PersL is different from that of PL. The luminescent patterns can make a difference as the change of concentration and time, forming a dynamic anti-counterfeiting mark that distinguishes in color and time. Thus, Ca2Sb2O7:Pr3+ has a bright application prospect in dynamic anti-counterfeiting field. 相似文献
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研究了正则的素数阶循环图,提出了计算多色Ramsey数R(q1,q2,…,qn)的下界的一个算法,得到4个三色Ramesey数的新下界:R(3,3,10)≥104,R(3,3,15)≥212,R(3,3,16)≥258,R(3,3,17)≥282。 相似文献
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《Ceramics International》2017,43(5):4440-4449
A series of size controllable Tb3+ and/or Eu3+ activated nano-sized silica phosphors have been successfully synthesized through a facile sol-gel method. The structure, morphology, compositions, and luminescence properties of as-prepared samples were well investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and photoluminescence spectroscopy (PL). The results showed that all as-prepared samples were spherical nanoparticles but the sizes reduced gradually with the temperature increased from 25 °C to 65 °C, which was contrary to the BET surfaces as well as the luminescence intensity. Under ultraviolet excitation, the SiO2:Ln3+(Ln=Eu, Tb) spherical nanoparticles showed characteristic red and green emissions corresponding to f-f transition of Eu3+ and Tb3+, respectively. Moreover, the luminescence emissions of samples can be tuned from green to yellow, orange and red by co-doping the Tb3+ and Eu3+ ions in different concentration ratio into the SiO2 host due to the efficient dipole–dipole energy transfer mechanism from Tb3+ to Eu3+ under 377 nm excitation. These results show that as-prepared phosphors may find potential applications in color display fields. 相似文献
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Per Baunegaard With Jensen Jakob Kjelstrup-HansenHorst-Günter Rubahn 《Organic Electronics》2013,14(12):3324-3330
Self-assembled, molecular crystalline nanofibers form microscale light-emitters for future nanophotonic applications. Such organic nanofibers exhibit many interesting optoelectronic properties, including polarized photo- and electroluminescence, waveguiding, and emission color tunability. Surface-grown nanofibers from two different molecules are implemented in an organic field-effect transistor platform by a double roll-printing scheme. Roll-printing multiple types of nanofibers onto the same device provides a fast and simple alternative to multilayer devices. The combination of nanofibers made from para-hexaphenylene and 5,5′-di-4-biphenyl-2,2′-bithiophene results in a nanofiber based organic light-emitting transistor (OLET) which emits both blue and green light. A comparison of measured electrical transport and electroluminescence (EL) properties results in a correlation between the threshold voltage for transport and the onset voltage for EL emission. 相似文献
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Pedro Jose Rivero Javier Goicoechea Aitor Urrutia Francisco Javier Arregui 《Nanoscale research letters》2013,8(1):101
In this paper, the influence of variable molar ratios between reducing and loading agents (1:100, 1:50, 1:20, 1:10, 1:5, 1:2, 1:1, 2:1) and between protective and loading agents (0.3:1, 0.75:1, 1.5:1, 3:1, 7.5:1, 30:1, 75:1) in the synthesis of silver nanoparticles by chemical reduction has been evaluated to obtain multicolor nanoparticles with a high stability in time. The protective agent poly(acrylic acid, sodium salt) (PAA) and reducing agent dimethylaminoborane (DMAB) play a key role in the formation of the resultant color. Evolution of the optical absorption bands of the silver nanoparticles as a function of PAA and DMAB molar ratios made it possible to confirm the presence of silver nanoparticles or clusters with a specific shape. The results reveal that a wide range of colors (violet, blue, green, brown, yellow, red, orange), sizes (from nanometer to micrometer), and shapes (cubic, rod, triangle, hexagonal, spherical) can be perfectly tuned by means of a fine control of the PAA and DMAB molar concentrations. 相似文献
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The Yb3+/Tm3+/Ho3+: Gd3Ga5O12 nano-crystals have been successfully prepared via a citric acid complex procedure. The luminescence spectra were measured and the up-conversion processes were discussed. By means of adjusting the doping concentrations of Yb3+/Tm3+/Ho3+, the red-green-blue up-conversion luminescence changed obviously. Results indicated that the ratio of red-green-blue up-conversion emissions enhanced heavily with the increasing concentrations of Tm3+ doped in the Yb3+/Tm3+/Ho3+:Gd3Ga5O12 nano-crystals, which was rooted in the three-photon resonant cross relaxation processes(1G4 (Tm) + 5I7 (Ho) → 3H5 (Tm) + 5S2 (Ho)). The tunable red-green-blue luminescence could be used in the fields of display, illumination, and photonics such as the white light generation. 相似文献
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