Solution-processed metal oxide thin-film transistors (TFTs) operating in enhancement mode are promising for the next-generation flat panel displays. In this work, we report high-mobility TFTs based on SnO2 active layer derived from a soluble tin(II) 2-ethylhexanoate precursor. Densely packed polycrystalline SnO2 thin films with moderate oxygen vacancies and only a few hydroxides are obtained via systemically optimizing precursor concentrations and processing conditions. The utilization of a solution-processed high-? Al2O3 insulating layer could generate a coherent dielectric/semiconductor interface, hence further improving the device performance. TFT devices with an average field-effect mobility of 96.4 cm¬¬2 V-1 s-1, a current on/off ratio of 2.2 × 106, a threshold voltage of 1.72 V and a subthreshold swing of 0.26 V dec-1 have been achieved, and the driving capability is demonstrated by implementing a single SnO2 TFT device to tune the brightness of an organic light-emitting diode. It is worth noting that these TFTs work in enhancement mode at low voltages less than 4 V, which sheds light on their potential application to the next-generation low-cost active matrix flat panel displays.
Abstract Objective: To explore the antitumor effects of low-intensity focused ultrasound (LIFU) mediated localized drug delivery of adriamycin-microbubble-PLGA nanoparticle complexes on rabbits VX2 liver tumor. Methods: ADM-NMCs were prepared by covalent linking of ADM-PLGA nanoparticles (ADM-NPs) to the shell of the microbubbles. A fixed water bag filled with microbubbles was subjected to LIFU and non-focused ultrasound respectively, and the ultrasound images of which were recorded before and after ultrasonication. A total of 54 VX2 liver tumor-burdened rabbits were divided into six groups randomly, including control, ADM-NPs combined with LIFU, microbubbles combined with LIFU, ADM-NPs and microbubbles combined with LIFU, ADM-NMCs combined with LIFU and ADM-NMCs combined with Non-FUS. The tumor volume and volume inhibition rate (VIR) of tumor progression were calculated and compared. Apoptotic cells were labeled by terminal deoxyuridine nick end. Proliferating cell nuclear antigen was detected by immunohistochemistry. The median survival time of the animals were recorded and compared. Results: ADM-NMCs were successfully prepared with an average diameter of 1721?nm. The highest VIR and apoptotic index (AI) were found in the group of ADM-NMCs combined with LIFU while the lowest proliferating index (PI) was simultaneously observed in this group. The median survival time of the rabbits in the ADM-NMCs combined with LIFU group was the longest (71days) among all groups. Conclusions: ADM-NMCs combined with LIFU could inhibit the rabbits VX2 liver tumor progress by delaying the tumor proliferation and accelerating apoptosis, which presents a novel process for liver tumor targeting chemotherapy.
We demonstrate a solution method of volatilize-controlled oriented growth (VOG) to fabricate aligned single crystals of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) on a Si/SiO2 substrate. Through controlling the evaporation rate of the solvent, large-area-aligned single-crystal layers can be achieved on several substrates at the same time, covering over 90% on 2 × 1 cm substrates. The method provides a low-cost, maneuverable technology, which has potential to be used in batch production. We find that the atmosphere of the solvent with high dissolving capacity is in favor of aligned single-crystal growth. Besides, the growth mechanism of the VOG method is investigated in this paper. Top-contact organic field-effect transistors based on the single crystals of TIPS pentacene are achieved on a Si/SiO2 substrate. The optimal device exhibits a field-effect mobility of 0.42 cm(2) V(-1) s(-1) and an on/off current ratio of 10(5). Our research indicates that the VOG method is promising in single-crystal growth on a Si/SiO2 substrate for commercial production.
The development of pure-blue-to-deep-blue-emitting ionic phosphors is an ultimate challenge for full-color displays and white-light sources. Herein we report two series of short-wavelength light-emitting cationic iridium(III) complexes with nonconjugated ancillary and cyclometalating ligands, respectively. In the first series, nonconjugated 1-[(diphenylphosphino)methyl]-3-methylimidazolin-2-ylidene-C,C2' (dppmmi) is used as the ancillary ligand and 2-phenylpyridine (ppy), 2-(2,4-difluorophenyl)pyridine (dfppy), and 1-(2,4-difluorophenyl)-1H-pyrazole (dfppz) are used as cyclometalating ligands. In the second one, nonconjugated 2,4-difluorobenzyl-N-pyrazole (dfbpz) is used as the cyclometalating ligand and 3-methyl-1-(2-pyridyl)benzimidazolin-2-ylidene-C,C(2)' (pymbi) as the ancillary ligand. The synthesis and photophysical and electrochemical properties, together with the X-ray crystal structures of these complexes, have been investigated. At room temperature, blue-emitting complexes [Ir(ppy)2(dppmmi)]PF6 (1) and [Ir(dfppy)2(dppmmi)]PF6 (2; PF6(-) is hexafluorophosphate) show much larger photoluminescence quantum yields of 24% and 46%, respectively. On the contrary, for complexes [Ir(dfppz)2(dppmmi)]PF6 (3) and [Ir(dfbpz)2(pymbi)]PF6 (4), deep-blue luminescence is only observed at low temperature (77 K). Density functional theory calculations are used to rationalize the differences in the photophysical behavior observed upon changes of the ligands. It is shown that the electronic transition dipoles of cationic iridium complexes 1 and 2 are mainly confined to cyclometalated ligands ((3)MLCT and LC (3)?-?*) and those of complex 3 are confined to all of the ligands ((3)MLCT, LC (3)?-?*, and (3)LLCT) because of the high LUMO energy level of dfppz. The emission of 4 mainly originates from the central iridium(III) ion and cyclometalated ligand to ancillary ligand charge transfer ((3)MLCT and (3)LLCT), in contrast to commonly designed cationic complexes using carbene-type ancillary ligands, where emission originates from the cyclometalated main ligands. Solution-processed organic light-emitting diodes based on complexes 1 and 2 gave blue-green (498 nm) and blue (478 nm) electroluminescence with maximum current efficiencies of 3.8 and 3.4 cd A(-1), respectively. The results indicate that introducing nonconjugated ligands into cationic iridium complexes is an effective means of achieving short-wavelength light-emitting phosphors.
An organic phototransistor (OPT) shows nonvolatile memory effect due to its novel optical writing and electrical erasing processes. In this work, we utilize an organic light-emitting diode (OLED) as the light source to investigate OPT-based memory (OPTM) performance. It is found that the OPTM can be used as either flash memory or write-once read-many-times memory by adjusting the properties of the Ta2O5 gate dielectric layer. UV/ozone treatment is applied to effectively change dielectric properties of the Ta2O5 film. The mechanisms for this are examined by X-ray photoelectron spectroscopy and capacitance-voltage measurement. It turns out that the densities of oxygen vacancies and defects in the first 1.8 nm Ta2O5 films near the Ta2O5/semiconductor interface are reduced. Furthermore, for the first time, we use this multifunctional OPTM, which unites the photosensitive and memory properties in one single device, as an optical feedback system to tune the brightness of the OLED. Our study suggests that these OPTMs have potential applications in tuning the brightness uniformity, improving the display quality and prolonging the lifetime of flat panel displays.
Various works on modification of the indium-tin oxide (ITO) substrate have been carried out so as to enhance hole injection in organic light-emitting devices. Herein, a simple and efficient approach to tuning the work function of the ITO substrate is described by surface modification of ITO with an organosiloxane self-assembled monolayer. The influences of the electronegativity on modification of the ITO substrate are systematically investigated by attaching electron-withdrawing groups (Cl, Br, and I) and an electron-donating group (NH2) to the organosiloxane materials. The preparation and modification of the ITO substrate has been studied using primarily atomic force microscopy and X-ray photoelectron spectroscopy and vacuum-ultraviolet spectroscopy, and remarkable changes have been observed after modification. The device based on a 3Cl-Si-ITO-modified anode exhibits the best efficiency among the devices, better than the control devices based on bare ITO, UV-treated ITO, and even Cl-ITO.
A novel bipolar host material, which meets the requirements of high triplet energy, good charge carrier transport properties, high solubility, and film-forming ability at the same time, has been designed and synthesized. Utilizing a new compound as host material, high-efficiency solution-processed blue and white phosphorescent organic light-emitting diodes (PHOLEDs) have been achieved.
We present here the development of a new solution-processable n-type dopant, N-DMBI. Our experimental results demonstrated that a well-known n-channel semiconductor, [6,6]-phenyl C(61) butyric acid methyl ester (PCBM), can be effectively doped with N-DMBI by solution processing; the film conductivity is significantly increased by n-type doping. We utilized this n-type doping for the first time to improve the air-stability of n-channel organic thin-film transistors, in which the doping can compensate for the electron traps. Our successful demonstration of n-type doping using N-DMBI opens up new opportunities for the development of air-stable n-channel semiconductors. It is also potentially useful for application on solution-processed organic light-emitting diodes and organic photovoltaics.
An ambipolar transporting naphtho[2,3-c][1,2,5]thiadiazole derivative with both high electron and hole mobilities has been synthesized via Suzuki cross-coupling. The electron and hole mobilities are 1.7 x 10(-3) cm(2)/ (V.s) and 1.9 x 10(-3) cm(2)/ (V.s) at an electric field of 4.5 x 10(5) V/cm, respectively, as measured by using time-of-flight technique.
A 115 days feeding trial was conducted to evaluate the effect of dietary cyanobacteria on growth, microcystins (MCs) accumulation in hybrid tilapia (Oreochromis niloticusxO. aureus) and the recovery when the fish were free of cyanobacteria. Three experimental diets were formulated: the control (cyanobacteria free diet); one test diet with cyanobacteria from Lake Taihu (AMt, 80.0 microg MCs g(-1) diet) and one with cyanobacteria from Lake Dianchi (AMd, 410.0 microg MCs g(-1) diet). Each diet was fed to fish for 60 days and then all fish were free of cyanobacteria for another 55 days. A significant increase in feeding rate (FR) was observed in fish fed AMd diet after a first 30-day exposure (1(st) EP), and in fish fed both AMt diet and AMd diet after a second 30-day exposure (2(nd) EP). Specific growth rates (SGR) of fish fed AMt diet and AMd diet were both obviously affected after the first 30-day exposure, but SGR was only significantly affected in fish fed AMt diet after the second 30-day exposure. After a 55-day recovery, there were no significant differences among diets in the indices mentioned above. Much higher concentrations of MCs were accumulated in tissues of all fish exposed to cyanobacteria. After the 55-day recovery, MC concentrations in fish tissues were significantly lower than those on day 60.
Films of zinc tin oxide (ZTO), grown from solutions with zinc acetate dehydrate and tin(II) 2-ethylhexanoate dissolved in 2-methoxyethanol, have been used to fabricate thin-film transistors in combination with solution-processed aluminum oxide as the gate insulator. And the nonhomogeneity of the single-layer ZTO films, caused by both ZTO film-substrate interaction and surface crystallization, has been studied, which is essential to achieve high performance transistors. In the bottom-contact thin-film transistor based on a Sn-rich layer of ZTO, a high mobility of 78.9 cm(2) V(-1) s(-1) in the saturation region has been obtained, with an on-to-off current ratio of 10(5) and a threshold gate voltage of 1.6 V.
A 120-day toxicity experiment was conducted to investigate the effect of dietary cyanobacteria on the growth and liver histopathology of yellow catfish, and subsequent recovery when the fish were free of cyanobacteria. Three experimental diets were formulated: the control (cyanobacteria-free diet), low-cyanobacteria diet (LCD, 32.3 ?g microsystins/g) and high-cyanobacteria diet (HCD, 71.96 ?g microsystins/g). Each diet was fed to fish for 60 days and then all fish were free of cyanobacteria for a further 60 days. The results showed that a significant decrease in the specific growth rate (SGR) was observed in both fish fed with the LCD and HCD after a 1st 30-day exposure period, however, no significant difference in the SGR between the LCD and control groups was observed after a 2nd 30-day exposure period. At the end of the 60 days exposure, all examined liver tissues in both doses exhibited what appeared as dose-dependent histopathological modifications. After a 60-day recovery, there were no significant differences in the SGR among groups, while no obvious histopathological alteration was observed in livers of fish previously fed with the LCD. The results indicate that the LCD-treated fish have a full recovery after a 60-day recovery, but the HCD-treated fish did not.
A carbazole-based diazahelicene, 2,12-dihexyl-2,12-diazahelicene (1), was synthesized by a photochemical synthesis and its use as a deep-blue dopant emitter in an organic light-emitting diode (OLED) was examined. Compound 1 exhibited good solubility and excellent thermal stability with a high decomposition temperature (T(d)=372.1?°C) and a high glass-transition temperature (T(g), up to 203.0?°C). Single-crystal structural analysis of the crystalline clathrate (1)(2)?cyclohexane along with a theoretical investigation revealed a non-planar-fused structure of compound 1, which prevented the close-packing of molecules in the solid state and kept the molecule in a good amorphous state, which allowed the optimization of the properties of the OLED. A device with a structure of ITO/NPB (50?nm)/CBP:5?% 1 (30?nm)/BCP (20?nm)/Mg:Ag (100?nm)/Ag (50?nm) showed saturated blue light with Commission Internationale de LEclairage (CIE) coordinates of (0.15, 0.10); the maximum luminance efficiency and brightness were 0.22?cd?A(-1) (0.09?Lm?W(-1)) and 2365?cd?m(-2), respectively. This new class of helicenes, based on carbazole frameworks, not only opens new possibilities for utilizing helicene derivatives in deep-blue-emitting OLEDs but may also have potential applications in many other fields, such as molecular recognition and organic nonlinear optical materials.
Intramolecular ?-? stacking interaction in one kind of phosphorescent cationic iridium complexes has been controlled through fluorination of the pendant phenyl rings on the ancillary ligands. Two blue-green-emitting cationic iridium complexes, [Ir(ppy)(2)(F2phpzpy)]PF(6) (2) and [Ir(ppy)(2)(F5phpzpy)]PF(6) (3), with the pendant phenyl rings on the ancillary ligands substituted with two and five fluorine atoms, respectively, have been synthesized and compared to the parent complex, [Ir(ppy)(2)(phpzpy)]PF(6) (1). Here Hppy is 2-phenylpyridine, F2phpzpy is 2-(1-(3,5-difluorophenyl)-1H-pyrazol-3-yl)pyridine, F5phpzpy is 2-(1-pentafluorophenyl-1H-pyrazol-3-yl)-pyridine, and phpzpy is 2-(1-phenyl-1H-pyrazol-3-yl)pyridine. Single crystal structures reveal that the pendant phenyl rings on the ancillary ligands stack to the phenyl rings of the ppy ligands, with dihedral angles of 21°, 18°, and 5.0° between least-squares planes for complexes 1, 2, and 3, respectively, and centroid-centroid distances of 3.75, 3.65, and 3.52 Å for complexes 1, 2, and 3, respectively, indicating progressively reinforced intramolecular ?-? stacking interactions from complexes 1 to 2 and 3. Compared to complex 1, complex 3 with a significantly reinforced intramolecular face-to-face ?-? stacking interaction exhibits a significantly enhanced (by 1 order of magnitude) photoluminescent efficiency in solution. Theoretical calculations reveal that in complex 3 it is unfavorable in energy for the pentafluorophenyl ring to swing by a large degree and the intramolecular ?-? stacking interaction remains on the lowest triplet state.
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