PbS/PbSe Hollow Spheres: Solvothermal Synthesis, Growth Mechanism, and Thermoelectric Transport Property

Uniform PbS/PbSe hollow spheres consisting of PbS and PbSe nanoparticles were synthesized by a facile solvothermal method in mixtures of ethylene glycol and tetrahydrofuran at 120 °C with the assistance of thioglycollic acid. Experimental parameters, such as reaction time, volume of thioglycollic acid, and volume ratio of ethylene glycol to tetrahydrofuran, played crucial roles in determining the morphologies and composites of the final products. Based on the electron microscope observations and X-ray diffraction (XRD) patterns, the reaction process and growth mechanism of such hierarchitectures were proposed. Nitrogen adsorption–desorption measurements and pore size distribution analysis revealed that the mesoporous existed in the product. Moreover, thermoelectric transport measurements demonstrated that the synergistic effects of PbS and PbSe would lead to enhancement of the electrical conductivity; the obtained binary phased PbS/PbSe hollow spheres had the maximum electrical conductivity and Seebeck coefficient of 22.1 S cm^–1 and 323.3 μV/K, respectively, which were higher than those of pure PbSe nanoparticles

Fusion at the Non-K-Region of Pyrene: An Alternative Strategy To Extend the π‑Conjugated Plane of Pyrene

A large fused pyrene derivative <b>TTTP</b> was facilely developed through fusion at the non-K-region of pyrene, which represents the first example of extending such a π-conjugated plane at its non-K-region. The investigation of its photophysical properties and other characterizations indicated that <b>TTTP</b> exhibited strong aggregation behaviors and self-assembled into highly ordered one-dimensional nanowires due to its large π-conjugated plane

Systematic Investigation of Isoindigo-Based Polymeric Field-Effect Transistors: Design Strategy and Impact of Polymer Symmetry and Backbone Curvature

Ten isoindigo-based polymers were synthesized, and their photophysical and electrochemical properties and device performances were systematically investigated. The HOMO levels of the polymers were tuned by introducing different donor units, yet all polymers exhibited <i>p</i>-type semiconducting properties. The hole mobilities of these polymers with centrosymmetric donor units exceeded 0.3 cm² V^–1 s^–1, and the maximum reached 1.06 cm² V^–1 s^–1. Because of their low-lying HOMO levels, these copolymers also showed good stability upon moisture. AFM and GIXD analyses revealed that polymers with different symmetry and backbone curvature were distinct in lamellar packing and crystallinity. DFT calculations were employed to help us propose the possible packing model. Based on these results, we propose a design strategy, called “molecular docking”, to understand the interpolymer π–π stacking. We also found that polymer symmetry and backbone curvature affect interchain “molecular docking” of isoindigo-based polymers in film, ultimately leading to different device performance. Finally, our design strategy maybe applicable to other reported systems, thus representing a new concept to design conjugated polymers for field-effect transistors

Electron-Deficient Poly(<i>p</i>‑phenylene vinylene) Provides Electron Mobility over 1 cm² V^–1 s^–1 under Ambient Conditions

Poly­(<i>p</i>-phenylene vinylene) derivatives (PPVs) are one of the most widely investigated <i>p</i>-type polymers in organic electronics. PPVs generally exhibit electron mobilities lower than 10^–4 cm² V^–1 s^–1, thus hindering their applications in high-performance polymer field-effect transistors and organic photovoltaics. Herein, we design and synthesize a novel electron-deficient PPV derivative, benzodifurandione-based PPV (<b>BDPPV</b>). This new PPV derivative displays high electron mobilities up to 1.1 cm² V^–1 s^–1 under ambient conditions (4 orders of magnitude higher than those of other PPVs), because it overcomes common defects in PPVs, such as conformational disorder, weak interchain interaction, and a high LUMO level. <b>BDPPV</b> represents the first polymer that can transport electrons over 1 cm² V^–1 s^–1 under ambient conditions

T‑Shaped Donor–Acceptor Molecules for Low-Loss Red-Emission Optical Waveguide

A series of T-shaped polycyclic molecules with high fluorescence were developed as optical waveguide materials. Their emissions covered almost the whole visible range from 450 to 800 nm. Compound 3-1 showed an optical loss coefficient about 0.29 dB/μm in red-emission waveguide. Our investigations demonstrated that these molecules held great potential for organic optical waveguide due to the high fluorescence quantum efficiency and large Stokes’ shift

Fluorescence Ratiometric Sensor for Trace Vapor Detection of Hydrogen Peroxide

Trace vapor detection of hydrogen peroxide (H₂O₂) represents a practical approach to nondestructive detection of peroxide-based explosives, including liquid mixtures of H₂O₂ and fuels and energetic peroxide derivatives, such as triacetone triperoxide (TATP), diacetone diperoxide (DADP), and hexamethylene triperoxide diamine (HMTD). Development of a simple chemical sensor system that responds to H₂O₂ vapor with high reliability and sufficient sensitivity (reactivity) remains a challenge. We report a fluorescence ratiometric sensor molecule, diethyl 2,5-bis­((((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)­benzyl)­oxy)­carbonyl)­amino)­terephthalate (DAT-B), for H₂O₂ that can be fabricated into an expedient, reliable, and sensitive sensor system suitable for trace vapor detection of H₂O₂. DAT-B is fluorescent in the blue region, with an emission maximum at 500 nm in the solid state. Upon reaction with H₂O₂, DAT-B is converted to an electronic “push–pull” structure, diethyl 2,5-diaminoterephthalate (DAT-N), which has an emission peak at a longer wavelength centered at 574 nm. Such H₂O₂-mediated oxidation of aryl boronates can be accelerated through the addition of an organic base such as tetrabutylammonium hydroxide (TBAH), resulting in a response time of less than 0.5 s under 1 ppm of H₂O₂ vapor. The strong overlap between the absorption band of DAT-N and the emission band of DAT-B enables efficient Förster resonance energy transfer (FRET), thus allowing further enhancement of the sensing efficiency of H₂O₂ vapor. The detection limit of a drop-cast DAT-B/TBAH film was projected to be 7.7 ppb. By combining high sensitivity and selectivity, the reported sensor system may find broad application in vapor detection of peroxide-based explosives and relevant chemical reagents through its fabrication into easy-to-use, cost-effective kits

Image_1_Involvement of 5-HT1A receptors of the thalamic descending pathway in the analgesic effect of intramuscular heating-needle stimulation in a rat model of lumbar disc herniation.JPEG

BackgroundIntramuscular (IM) heating-needle therapy, a non-painful thermal therapy, has been found to exert an analgesic effect via the thalamic ventromedial (VM) nucleus, solely by reducing the triggering threshold for descending inhibition; this could be modulated by intracephalic 5-hydroxytryptamine-1A (5-HT1A) receptors, rather than via the regular analgesia pathway. In this study, the effect and the potential serotonergic mechanism of IM heating-needle stimulation at 43°C were explored in the case of the pathological state of lumbar disc herniation (LDH).MethodsA modified classic rat model of LDH, induced via autologous nucleus pulposus implantation, was utilized. IM inner heating-needles were applied at the attachment point of skeletal muscle on both sides of the L4 and L5 spinous processes. WAY-100635 and 8-OH-DAPT, 5-HT1A receptor antagonist and agonist, were separately injected into the bilateral thalamic mediodorsal (MD) and VM nucleus via an intrathalamic catheter. Nociception was assessed by bilateral paw withdrawal reflexes elicited by noxious mechanical and heat stimulation.ResultsIM heating-needle stimulation at a temperature of 43°C for 30 or 45 min significantly relieved both mechanical and heat hyperalgesia in the rat model of LDH (P 0.05). Injection of 8-OH-DAPT into the thalamic MD nucleus exerted no modulating effects on either mechanical or heat hyperalgesia (P > 0.05).ConclusionIM heating-needle stimulation at 43°C for 30 min may activate 5-HT1A mechanisms, via the thalamic VM nucleus, to attenuate hyperalgesia in a rat model of LDH. This innocuous form of thermal stimulation is speculated to selectively activate the descending inhibition mediated by the thalamic VM nucleus, exerting an analgesic effect, without the involvement of descending facilitation of the thalamic MD nucleus.</p

Enhanced Molecular Packing of a Conjugated Polymer with High Organic Thermoelectric Power Factor

The detailed relationship between film morphology and the performance of solution processed n-type organic thermoelectric (TE) devices is investigated. It is interesting to find that the better ordered molecular packing of n-type polymer can be achieved by adding a small fraction of dopant molecules, which is not observed before. The better ordered structure will be favorable for the charge carrier mobility. Meanwhile, dopant molecules improve free carrier concentration via doping reaction. As a result, a significantly enhanced electrical conductivity (12 S cm^–1) and power factor (25.5 μW m^–1 K^–2) of TE devices are obtained. Furthermore, the phase separation of conjugated polymer/dopants is observed for the first time with resonant soft X-ray scattering. Our results indicate that the miscibility of conjugated polymers and dopants plays an important role on controlling the morphology and doping efficiency of TE devices

Balanced Ambipolar Organic Thin-Film Transistors Operated under Ambient Conditions: Role of the Donor Moiety in BDOPV-Based Conjugated Copolymers

Organic field-effect transistors (OFETs) are receiving an increased amount of attention because of their intriguing advantages such as flexibility, low cost, and solution processability. Development of organic conjugated polymers with balanced ambipolar carrier transportation operated under ambient conditions, in particular, is considered to be one of the central issues in OFETs. In this work, the 3,7-bis­[(<i>E</i>)-2-oxoindolin-3-ylidene]-3,7-dihydrobenzo­[1,2-<i>b</i>:4,5-<i>b</i>′]­difuran-2,6-dione (BDOPV) unit as a good acceptor unit was copolymerized with three donor moieties, thieno­[3,2-<i>b</i>]­thiophene (TT), benzo­[1,2-<i>b</i>:4,5-<i>b</i>′]­dithiophene (BDT), and benzo­[1,2-<i>b</i>:4,5-<i>b</i>′]­diselenophene (BDSe), to construct three donor–acceptor (D–A) conjugated polymers, <b>BDOPV–TT</b>, <b>BDOPV–BDT</b>, and <b>BDOPV–BDSe</b>. Photophysical and electrochemical properties of all the polymers were characterized. The fabrication of OFETs using three polymers as the active layers demonstrated that all the three polymers showed balanced ambipolar transport properties tested under ambient conditions, which is of great importance in complementary circuits. In particular, both electron and hole mobilities of <b>BDOPV–TT</b> were achieved above 1 cm² V^–1 s^–1 under ambient conditions (1.37 and 1.70 cm² V^–1 s^–1, respectively), showing great potential in balanced ambipolar OFETs

Odd–Even Effect of Thiophene Chain Lengths on Excited State Properties in Oligo(thienyl ethynylene)-Cored Chromophores

In a self-assembly material system, odd–even effects are manifested from long-range periodic packing motifs. However, in an amorphous material system, due to long-range disorder, such phenomena are less prone to appear. Here, we report the discovery of a remarkable odd–even effect on the excited state properties of a series of conjugated thienyl ethynylene (TE) oligomers with truxene as end-capping units, Tr­(TE)_<i>n</i>Tr (<i>n</i> = 2–6), in solution. Using steady-state and time-resolved spectral measurements, we found the fluorescence quantum yield and excited state dynamics, both showing odd–even alternation with increasing thiophene–ethynylene chain lengths in apolar cyclohexane (CHX). It is found that the symmetry properties with different torsional modes dominate the excited state processes. In polar tetrahydrofuran (THF), solvation lowers the twisting barriers, leading to symmetry breaking without special odd–even alternation over structures. The results presented here will be helpful for understanding odd–even effects of conjugated polymers and designing novel photoelectric materials