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A Radio-Fluorogenic Polymer-Gel Makes Fixed Fluorescent Images of Complex Radiation Fields
摘要： We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g., maleimido-pyrene (MPy). The radio-fluorogenic effect depends on copolymerization of the MPy into growing chains of TBA on radiation-induced polymerization. This converts the maleimido residue, which quenches the pyrene fluorescence, into a succinimido moiety (SPy), which does not. The intensity of the fluorescence is proportional to the yield of free-radicals formed and hence to the local dose deposited. Because the SPy moieties are built into the polymer network, the image is fixed. The method of preparing the gel and imaging the radiation-induced fluorescence are presented and discussed. The effect is illustrated with fluorescent images of the energy deposited in the gel by beams of X-rays, electrons, and protons as well as a radioactive isotope.
关键词： polymer gel dosimetry,radio-fluorogenic co-polymerization,radio-fluorogenic gel,3D dose imaging,proton beam imaging,tertiary-butyl acrylate gel
更新于2025-09-23 15:23:52
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Concentration quenching resistant donor-acceptor molecular structure for high efficiency and long lifetime thermally activated delayed fluorescent organic light-emitting diodes via suppressed non-radiative channel
摘要： A molecular design having t-butyl groups surrounding a donor-acceptor type core structure was developed as an approach to obtain high external quantum efficiency by suppressing concentration quenching effect caused by strong intermolecular interaction. The donor-acceptor type core structure was surrounded by six t-butyl groups to separate the donor-acceptor core structure between molecules. A heptazine acceptor and a diphenylamine donor based thermally activated delayed fluorescent emitter protected by the multiple t-butyl units achieved maximum external quantum efficiency of 32.6% at 1% doping concentration and 23.0% even at a high doping concentration of 20% by reducing concentration quenching effect. Furthermore, the lifetime of the thermally activated delayed fluorescent devices was also improved relative to that of the previous emitter with the same acceptor. The external quantum efficiency and device lifetime are better than any other results reported in the orange TADF OLEDs.
关键词： Thermally activated delayed fluorescence,Lifetime,T-butyl,Organic light-emitting diodes,High efficiency
更新于2025-09-23 15:21:01
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Theoretical and experimental studies on DC conductivity and temperature-dependent AC conductivity of poly(butyl methacrylate)/Nd-TiO <sub/>2</sub> nanocomposites
摘要： Electrically conductive nanocomposite system based on poly(butyl methacrylate) (PBMA) with different contents of neodymium-doped titanium dioxide (Nd-TiO2) was prepared by in situ free radical polymerization method. The effect of Nd-TiO2 on the morphology and structural properties of the composites was carried out by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD). The temperature-dependent AC conductivity and DC electrical conductivity of PBMA/Nd-TiO2 nanocomposites were studied with respect to the different volume fraction of Nd-TiO2 nanoparticles. SEM and XRD patterns revealed the uniform dispersion and structural regularity of nanoparticles in the polymer matrix. The AC conductivity of PBMA and its composites were found to be increased with an increase in temperatures and frequencies. The activation energy and exponential factor were analyzed from AC conductivity and both results indicate the hopping conduction mechanism present in PBMA/Nd-TiO2 nanocomposite, which is responsible for the variation of conductivity with temperature also. The DC conductivity of nanocomposites was higher than pure PBMA and the conductivity increases with increase in the concentration of Nd-TiO2 nanoparticles. Experimental and theoretical investigations based on McCullough, Bueche, Scarisbrick, and Mamunya modeling were carried out to observe the DC conductivity differences induced by the addition of Nd-TiO2 nanoparticles in PBMA matrix. Among the various modeling studied here, Mamunya model shows better agreement with the experimental conductivity.
关键词： Poly(n-butyl methacrylate),DC conductivity,conductivity modeling,temperature-dependent AC conductivity
更新于2025-09-19 17:15:36
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Low-temperature Interfacial Engineering for Flexible CsPbI2Br Perovskite Solar Cells with High Performance Beyond 15%
摘要： All-inorganic cesium lead halide (CsPbX3) perovskites exhibit superior thermal stability compared to the organic-inorganic hybrid counterparts. The power conversion efficiency (PCE) of CsPbI2Br perovskite solar cells (PSCs) has been over 16%. However, the high-temperature annealing limits its feasibility on flexible devices. Here, low-temperature processed flexible CsPbI2Br PSCs are designed by introducing Al-doped ZnO (AZO) as an electron-transport layer and tert-butyl cyanoacetate (t-BCA) as a passivation layer. The thickness-insensitive AZO significantly enhances the quality of perovskite films and the reproducibility of the PSCs. As well the t-BCA can effectively passivate the trap states and suppress charge recombination of CsPbI2Br films. The as-optimized flexible CsPbI2Br PSCs exhibits a high PCE of 15.08% (with the active area of 0.1 cm2), which is one of the highest efficiency for flexible all-inorganic PSCs. The devices show outstanding stability, retaining 93% of the original PCE after being stored 60 days, 91% and 86% of the initial efficiency after continuously heating 360 hours at 85 oC and stored under 65% RH for 30 hours, respectively. In addition, the PSCs exhibits excellent mechanical stability, remains 85% of original value after 1000 bending cycles at a curvature radius of 3 mm.
关键词： perovskite solar cells,tert-butyl cyanoacetate,passivation layer,All-inorganic cesium lead halide,flexible devices,low-temperature processed,Al-doped ZnO
更新于2025-09-19 17:13:59
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Quantitative remote and on-site Hg2+ detection using the handheld smartphone based optical fiber fluorescence sensor (SOFFS)
摘要： Di-n-butyl ether (DBE) is one of the most promising alternative biofuels for vehicles due to its superior physicochemical properties and because it is a renewable resource. This study investigated the effects of DBE addition on the spray macroscopic characteristics of diesel-biodiesel blends under various injection and ambient conditions. Three kinds of ternary blended fuels were prepared—(1) 72% diesel, 18% biodiesel, 10% DBE by volume (D72B18DBE10); (2) 64% diesel, 16% biodiesel, 20% DBE by volume (D64B16DBE20); and (3) 56% diesel, 14% biodiesel, and 30% DBE by volume (D56B14DBE30)—in order to compare their spray characteristics with those of an 80% diesel–20% biodiesel mix (D80B20) and conventional diesel (D100). The experiments were conducted in a constant volume chamber with a high-pressure common rail injection system using a high-speed photography method. The results show that D80B20 gives the longest spray tip penetration and the smallest cone angle and projected area among the five test fuels. With increased DBE blending ratio, the spray penetration length decreases slightly, and spray cone angle and projected area increase. When the DBE volume fraction in the ternary blend is 20%, the spray tip penetration, cone angle, and projected area are comparable to those of diesel. In addition, air entrainment characteristics were analyzed with the quasi-steady jet theory. It was found that the addition of DBE can improve the air entrainment characteristics of diesel-biodiesel blends, and D64B16DBE20 results in fuel-air mixing similar to that of D100.
关键词： Biodiesel,Diesel,Di-n-butyl ether,Spray characteristics
更新于2025-09-19 17:13:59
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Removal of Methyl Tertiary-Butyl Ether via ZnO-AgCl Nanocomposite Photocatalyst
摘要： ZnO-AgCl nanocomposites with different mass ratios were synthesized via a one-pot wet chemical method. The synthesized nanocomposites were characterized by SEM, XRD and photoluminescence spectroscopy. The ZnO-AgCl nanocomposites exhibited a significant enhancement of photocatalytic activity towards degradation of methyl tertiary butyl ether in aqueous solution due to the effective carrier separation performance. In addition, the proposed ZnO-AgCl also exhibited an excellent photostability.
关键词： ZnO,Methyl tertiary butyl ether,Photostability,AgCl,Photocatalysis
更新于2025-09-11 14:15:04
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Analyzing the Influence of Substituents on Proton Tautomerization - a Comparison of tetra- <i>tert</i> -Butyl Phthalocyanine Isomers
摘要： We present a comparative study of tetra-tert-butyl phthalocyanine (ttbPc) isomers on a Ag(111) surface by means of low temperature scanning tunneling microscopy to analyze the influence of substituents on the tautomerization, a proton transfer reaction, in single molecules. By comparing ttbPc with the well studied phthalocyanine (H2Pc) molecule, we demonstrate a decoupling from the surface by the tert-butyl substituents. A comparison between the four ttbPc isomers, which naturally exist due to different bonding positions of the tert-butyl groups on the macrocycle, reveals a significant influence of the structural differences on their tautomerization behavior, as evidenced by a switching rate which varies by up to a factor of four between ttbPc isomers. These findings can be understood by an energetic landscape of the proton switch which links the binding distance of tert-butyl groups with the height of potential barriers. This model is supported by the analysis of two types of deprotonated ttbPc molecules with the molecular nanoprobe (MONA) technique.
关键词： tetra-tert-butyl phthalocyanine,proton transfer,scanning tunneling microscopy,tautomerization,isomers
更新于2025-09-09 09:28:46
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Effects of n-butyl amine incorporation on the performance of perovskite light emitting diodes
摘要： The efficiency of perovskite light emitting diodes (PeLEDs) is crucially limited by leakage current and nonradiative recombination. Here we introduce n-butyl amine (BA) to modulate the growth of perovskite films as well as improve the performance of PeLEDs, and investigate in details the effects of BA incorporation on the structural, optical, and electrical characteristics of perovskite films. The results indicate that BA would terminate the grain surface and inhibit crystal growth, leading to increased radiative recombination. However, BA overload would make the films loose and recreate shunt paths. The electrical detriment of BA overload outweighs its optical benefit. As a result, optimal PeLEDs can be obtained only with moderate BA incorporation.
关键词： optical and electrical characteristics,butyl amine,crystal growth,bulky organic cations,perovskite light emitting diodes
更新于2025-09-04 15:30:14