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1.
Herein, the photophysical, morphological, optical gain characteristics of a set of trigonal monodisperse starburst conjugated macromolecules ( Tr1‐Tr4 ) have been systematically investigated in order to elucidate the influence of the molecular structures on their optoelectronic performance. With increasing the oligofluorene arm length, absorption spectra were red‐shifted progressively, whereas an increase in photoluminescence quantum yields (PLQYs) and optical gain coefficients, and a corresponding reduction in amplified spontaneous emission (ASE) thresholds and loss coefficients were observed for Tr1‐Tr3 except for Tr4 . The results indicate that the effective conjugation length become saturated for Tr3 in this system. Impressively, the resulting molecules manifested very low ASE thresholds (4.4–11.6 μJ cm?2) with high photostability, as well as high thermal stability. One dimensional distributed feedback (DFB) lasers exhibited a minimum lasing threshold of 10.38 nJ pulse?1 (0.86 kW cm?2, 4.325 μJ cm?2) for Tr3 . It should be emphasized that the ASE threshold of Tr1‐Tr4 was nearly unchanged from room temperature to 200 °C. The results suggest that this kind of truxene‐cored conjugated starbursts with high photostability and low lasing thresholds are rather promising gain media for organic semiconductor lasers.  相似文献   

2.
A set of fluorene-capped pendant conjugated molecules ( T-m and T-p ), which consist of a triazine center with three carbazole substituents as the donor–acceptor (D-A) type pendant structure, were designed, synthesized, and investigated as gain media for organic semiconductor lasers (OSLs). In particular, varying the capping positions of the fluorene units on the pendant core structures results in significantly different intramolecular charge transfer (ICT) properties, where T-m manifested depressed ICT characteristic and high fluorescence quantum yield. The lowest amplified spontaneous emission (ASE) threshold in neat films was recorded as 1.9 μJ cm−2 for T-m and 83.8 μJ cm−2 for T-p , which indicated that the depressed ICT characteristics in the case of T-m help to enhance the ASE properties. Remarkably, the ASE threshold remained almost unchanged and the ASE spectra showed very small shifts (within 1 nm) for T-m with film samples annealed up to 180 °C in open air. In contrast, its linear counterpart 2FEtCz-m showed a clearly increased ASE threshold upon annealing above 100 °C. The results suggest that the selective construction of conjugated pendant molecules with depressed ICT characteristics is beneficial for finely modulating the optical and electrical properties as well as improving the thermostability and photostability, which manifests the great potential as a robust gain media for OSLs.  相似文献   

3.
A reliable synthetic protocol toward a series of fused chalcogenopheno[1]benzochalcogenophene (CBC) building blocks was developed based on a Fiesselmann reaction. The obtained CBC units were applied in McMurry and Stille coupling reactions toward symmetric regioisomeric ene-linked dimers. These π-conjugated compounds were characterized regarding their photophysical and electrochemical properties and proved to be materials with reduced HOMO–LUMO gaps compared to their sulfur-based analogues. Single-crystal X-ray diffraction experiments revealed strong intermolecular selenium–selenium and selenium–carbon interactions depending on the position and number of incorporated selenium atoms. Good field-effect transistor performance with charge carrier mobilities up to 4×10−3 cm2 V−1 s−1 and high on/off ratios could be observed.  相似文献   

4.
In this paper, we described the design, synthesis, and characterization of two novel naphthalene diimide (NDI) core-based targets modified with terminal fullerene (C60) yield – so called S4 and S5 , in which NDI bearing 1 and 2 molecules of C60, respectively. The absorption, electrochemical and thin-film transistor characteristics of the newly developed targets were investigated in detail. Both S4 and S5 displayed broad absorption in the 450–500 nm region, owing to the effect of conjugation due to fullerene functionalities. The electrochemical measurement suggested that the HOMO and the LUMO energy levels can be altered with the number of C60 units. Both S4 and S5 were employed as organic semiconductor materials in n-channel transistors. The thin film transistor based on S4 exhibited superior electron mobility (μe) values ranging from 1.20×10−4 to 3.58×10−4 cm2 V−1 s−1 with a current on-off ratio varying from 102 to 103 in comparison with the performance of S5 based transistor, which exhibited μe ranging from 8.33×10−5 to 2.03×10−4 cm2 V−1 s−1 depending on channel lengths.  相似文献   

5.
Herein, we report the synthesis, characterization, and field‐effect properties of two cross‐conjugated dithienylmethanone (DMO)‐based alternating polymers, namely, PDMO‐S and PDMO‐Se . Both polymers possess high thermal stability, good solubility, and broad absorption spectra. Their electrochemical properties were investigated using cyclic voltammetry, indicating that PDMO‐Se has higher HOMO/LUMO energy levels of −5.49/−3.49 eV than −5.57/−3.58 eV of PDMO‐S . The two polymers exhibited promising charge transport properties with the highest hole mobility of 0.12 cm2 V−1 s−1 for PDMO‐S and 0.025 cm2 V−1 s−1 for PDMO‐Se . AFM and 2D‐GIXRD analyses demonstrated that the PDMO‐S formed lamellar, edge‐on packing thin film with close ππ stacking. These findings suggest that cross‐conjugated polymers might be potential semiconducting materials for low‐cost and flexible organic electronics. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1012–1019  相似文献   

6.
A conjugated copper(II) catecholate based metal–organic framework (namely Cu-DBC) was prepared using a D2-symmetric redox-active ligand in a copper bis(dihydroxy) coordination geometry. The π-d conjugated framework exhibits typical semiconducting behavior with a high electrical conductivity of ca. 1.0 S m−1 at room temperature. Benefiting from the good electrical conductivity and the excellent redox reversibility of both ligand and copper centers, Cu-DBC electrode features superior capacitor performances with gravimetric capacitance up to 479 F g−1 at a discharge rate of 0.2 A g−1. Moreover, the symmetric solid-state supercapacitor of Cu-DBC exhibits high areal (879 mF cm−2) and volumetric (22 F cm−3) capacitances, as well as good rate capability. These metrics are superior to most reported MOF-based supercapacitors, demonstrating promising applications in energy-storage devices.  相似文献   

7.
Typical n-type conjugated polymers are based on fused-ring electron-accepting building blocks. Herein, we report a non-fused-ring strategy to design n-type conjugated polymers, i.e. introducing electron-withdrawing imide or cyano groups to each thiophene unit of a non-fused-ring polythiophene backbone. The resulting polymer, n-PT1 , shows low LUMO/HOMO energy levels of −3.91 eV/−6.22 eV, high electron mobility of 0.39 cm2 V−1 s−1 and high crystallinity in thin film. After n-doping, n-PT1 exhibits excellent thermoelectric performance with an electrical conductivity of 61.2 S cm−1 and a power factor (PF) of 141.7 μW m−1 K−2. This PF is the highest value reported so far for n-type conjugated polymers and this is the first time for polythiophene derivatives to be used in n-type organic thermoelectrics. The excellent thermoelectric performance of n-PT1 is due to its superior tolerance to doping. This work indicates that polythiophene derivatives without fused rings are low-cost and high-performance n-type conjugated polymers.  相似文献   

8.
A soluble, green-blue fluorescent, π-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material. The presence of sliding π-stacked columns in the single crystal of dianthracenylazatrioxa[8]circulene is found to cause a very high electron-hopping rate, thus making this material a promising n-type organic semiconductor with an electron mobility predicted to be around 2.26 cm2 V−1 s−1. The best organic light-emitting diode (OLED) device based on the dianthracenylazatrioxa[8]circulene fluorescent emitter has a brightness of around 16 000 Cd m−2 and an external quantum efficiency of 3.3 %. Quantum dot-based OLEDs were fabricated by using dianthracenylazatrioxa[8]circulene as a host matrix material.  相似文献   

9.
A new bisphenol monomer containing a pair of electron‐rich tetra‐arylmethane units was designed and synthesized. Based on this monomer, along with commercial 4,4′‐(hexafluoroisopropylidene)diphenol A and 4,4′‐difluorobenzophenone, a series of novel poly(arylene ether ketone)s containing octasulfonated segments of varying molar percentage (x) (6F‐SPAEK‐x) were successfully synthesized by polycondensation reactions, followed by sulfonation. Tough, flexible, and transparent membranes, exhibiting excellent thermal stabilities and mechanical properties were obtained by casting. 6F‐SPAEK‐x samples exhibited appropriate water uptake and swelling ratios at moderate ion exchange capacities (IECs) and excellent proton conductivities. The highest proton conductivity (215 mS cm−1) is observed for hydrated 6F‐SPAEK‐15 (IEC = 1.68 meq g−1) at 100 °C, which is more than 1.5 times that of Nafion 117. Furthermore, the 6F‐SPAEK‐10 membrane exhibited comparable proton conductivity (102 mS cm−1) to that of Nafion 117 at 80 °C, with a relatively low IEC value (1.26 meq g−1). Even under 30% relative humidity, the 6F‐SPAEK‐20 membrane (2.06 meq g−1) showed adequate conductivity (2.1 mS cm−1) compared with Nafion 117 (3.4 mS cm−1). The excellent comprehensive properties of these membranes are attributed to well‐defined nanophase‐separated structures promoted by strong polarity differences between highly ionized and fluorinated hydrophobic segments. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 25–37  相似文献   

10.
A bright near-infrared (NIR) fluorescent molecule was developed based on the donor–acceptor–donor (D–A–D) approach using an aza-BODIPY analog called pyrrolopyrrole aza-BODIPY (PPAB) as an electron-accepting chromophore. Directly introducing electron-donating triphenylamine (TPA) to develop a D–A–D structure caused redshifts of absorption and emission of PPAB into the NIR region with an enhanced fluorescence brightness of up to 5.2×104 m −1 cm−1, whereas inserting a phenylene linker between the TPA donor and the PPAB acceptor induced solvatochromic behavior in emission. Transient absorption spectra and theoretical calculations revealed the presence of a highly emissive hybridized locally excited and charge-transfer state in the former case and the contribution of the dark charge-separated state to the excited state in the latter case. The bright D–A–D PPAB as a novel emitter resulted in a NIR electroluminescence with a high external quantum efficiency of 3.7 % and a low amplified spontaneous emission threshold of ca. 80 μJ cm−2, indicating the high potential for NIR optoelectronic applications.  相似文献   

11.
A new conjugated polymer (PBAIIDTT) based on bay‐annulated indigo and indacenodithieno[3,2‐b]thiophene was designed, synthesized, and characterized. PBAIIDTT shows strong absorption in 400–500 and 600–800 nm, and its HOMO and LUMO energy levels are −5.45 eV and −3.65 eV, respectively. In organic field‐effect transistors, the polymer exhibits a relatively high hole mobility of 0.39 cm2 V−1 s−1. PBAIIDTT was added to poly(3‐hexylthiophene) (P3HT) and phenyl‐C61‐butyric acid methyl ester (PC61BM) based organic solar cells. Ternary blend solar cells with 10% PBAIIDTT show an increased short circuit current density due to the broadened photocurrent generated in the near‐infrared region, and a power conversion efficiency of 3.78%, which is higher than that of the P3HT:PC61BM binary control devices (3.33%). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 213–220  相似文献   

12.
Two well‐defined alternating π‐conjugated polymers containing a soluble electroactive benzo[1,2‐b:4,5‐b′]difuran (BDF) chromophore, poly(BDF‐(9‐phenylcarbazole)) (PBDFC), and poly(BDF‐benzothiadiazole) (PBDFBTD) were synthesized via Sonogashira copolymerizations. Their optical, electrochemical, and field‐effect charge transport properties were characterized and compared with those of the corresponding homopolymer PBDF and random copolymers of the same overall composition. All these polymers cover broad optical absorption ranges from 250 to 750 nm with narrow optical band gaps of 1.78–2.35 eV. Both PBDF and PBDFBTD show ambipolar redox properties with HOMO levels of ?5.38 and ?5.09 eV, respectively. The field‐effect mobility of holes varies from 2.9 × 10?8 cm2 V?1 s?1 in PBDF to 1.0 × 10?5 cm2 V?1 s?1 in PBDFBTD. Bulk heterojunction solar cell devices were fabricated using the polymers as the electron donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester as the electron acceptor, leading to power conversion efficiencies of 0.24–0.57% under air mass 1.5 illumination (100 mW cm?2). These results indicate that their band gaps, molecular electronic energy levels, charge mobilities, and molecular weights are readily tuned by copolymerizing the BDF core with different π‐conjugated units. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

13.
A perfluorinated and alkylthiolated benzodithiophene (BDT)-ttTPD-based donor polymer (P2FS-ttTPD) was synthesized via a Stille polymerization, and found to have a number average molecular weight (Mn) of 13,000 g/mol (Đ = 2.3). P2FS-ttTPD has a wide bandgap (1.96 eV) and a deep highest occupied molecular orbital (HOMO) level (−5.70 eV). The perfluorination and alkylthiolation of the polymer backbone lower the polymer's HOMO level significantly. The hole and electron mobilities of P2FS-ttTPD were determined to be 1.12 × 10−4 and 9.38 × 10−7 cm2/V s, respectively. Polymer solar cell devices prepared with a P2FS-ttTPD:IT-4F (1:1) blend as the active layer were found to exhibit power conversion efficiencies of 4.15%, a short-circuit current density (JSC) of 10.29 mA/cm2, an open-circuit voltage (VOC) of 0.97 V, and a fill factor of 41.6%. The (1:1) blend devices were found to exhibit high VOC and low Eloss values.  相似文献   

14.
Nitrogen-linked hexaazatrinaphthylene polymer ( N2-HATN ) as organic cathode material with low HOMO–LOMO gap was synthesized and was observed to possess reversible high capacity and unexpected long-term cycling stability. The pre-treated N2-HATN and pRGO combination demonstrated good structure compatibility and the resultant cathode exhibited a constant increment of capacity during the redox cycles. The initial capacity at 0.05 A g−1 was 406 mA h−1 g−1, and increased to 630 mA h−1 g−1 after 70 cycles. At 0.5 A g−1 discharging rate, the capacity increased from an initial value of 186 mA h−1 g−1 to 588 mA h−1 g−1 after 1600 cycles. The pseudocapacitance-type behavior is postulated to be attributed to the structure compatibility between the active material and pRGO.  相似文献   

15.
Developing new D-A conjugated polymer system for thermoelectric (TE) application is highly desirable. Herein, a series of random copolymers by incorporating 3,4-ethylenedioxythiophene (EDOT) electron rich units into a diketopyrrolopyrrole (DPP) D-A conjugated polymer were designed and synthesized. Compared to the alternating conjugated copolymer PDPP-3T, the HOMO level of the random copolymers are increased as part of the electron deficiency acceptor DPP units in the polymer chain were superseded by electron rich EDOT, which could contribute to effective p-doping. Moreover, through incorporating EDOT to construct random copolymers, it can also induce an orientation change from face-on dominated to edge-on dominated orientation as well as enhance the packing of copolymer chains, which is beneficial to the charge transport. Under same doping condition, the electrical conductivities of the doped polymers increase and the Seebeck coefficient decrease as the increasing of EDOT content, resulting in an optimized power factor of 6.4 μW m−1 K−2 for the random polymer with EDOT content of 40% which is four times higher than that of alternating conjugated copolymer PDPP-3T. These results demonstrated that constructing random copolymers by incorporating more electronic donors into D-A conjugated polymers may be a promising strategy for developing TE conjugated polymers.  相似文献   

16.
A set of three donor‐acceptor conjugated (D‐A) copolymers were designed and synthesized via Stille cross‐coupling reactions with the aim of modulating the optical and electronic properties of a newly emerged naphtho[1,2‐b:5,6‐b′]dithiophene donor unit for polymer solar cell (PSCs) applications. The PTNDTT‐BT , PTNDTT‐BTz , and PTNDTT‐DPP polymers incorporated naphtho[1,2‐b:5,6‐b′]dithiophene ( NDT ) as the donor and 2,2′‐bithiazole ( BTz ), benzo[1,2,5]thiadiazole ( BT ), and pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione ( DPP ), as the acceptor units. A number of experimental techniques such as differential scanning calorimetry, thermogravimetry, UV–vis absorption spectroscopy, cyclic voltammetry, X‐ray diffraction, and atomic force microscopy were used to determine the thermal, optical, electrochemical, and morphological properties of the copolymers. By introducing acceptors of varying electron withdrawing strengths, the optical band gaps of these copolymers were effectively tuned between 1.58 and 1.9 eV and their HOMO and LUMO energy levels were varied between ?5.14 to ?5.26 eV and ?3.13 to ?3.5 eV, respectively. The spin‐coated polymer thin film exhibited p‐channel field‐effect transistor properties with hole mobilities of 2.73 × 10?3 to 7.9 × 10?5 cm2 V?1 s?1. Initial bulk‐heterojunction PSCs fabricated using the copolymers as electron donor materials and [6,6]‐phenyl C71 butyric acid methyl ester (PC71BM) as the acceptor resulted in power conversion efficiencies in the range of 0.67–1.67%. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2948–2958  相似文献   

17.
Eastern Brazilian Pegmatite Province includes many topaz-bearing pegmatitic bodies. Residual melts from the Fe–K-rich alkaline Medina granite (ca. 500 Ma) formed the Serrinha pegmatite—a system of branched thin pegmatite veins hosted by pink facies of the parent granite. The colourless topaz from Serrinha pegmatite contains both mineral and fluid inclusions. Microcline (513, 476, 456 cm−1), albite (507, 479, 457 cm−1), topaz (926, 858, 267, 239 cm−1), quartz (463 cm−1), rutile (610, 444 cm−1), wolframite (884 cm−1) and uranophane (968, 788 cm−1) represent solid inclusions formed by fluid-induced processes from the pneumatolytic (∼600–400 °C) to hydrothermal (<400 °C) stages of pegmatite crystallization. Fluid inclusions are mainly liquid or liquid-gas, which contain CO2 (marker bands ∼1388 cm−1 and ∼1285 cm−1) and traces of methane (2917 cm−1). They are mainly of primary and pseudo-secondary origin, indicating tectonic quiescence during and after topaz crystallization (in agreement with the post-collisional nature of the parent granite). Topaz crystallized in high temperature conditions of the pneumatolytic stage at a depth around 8.5–10.0 km.  相似文献   

18.
Two donor–acceptor conjugated polymers, PTSSO‐TT and PTSSO‐BDT, composed of acenaphtho[1,2‐c]thiophene ‐ S,S‐dioxide (TSSO) as a new electron acceptor and thienothiophene (TT) or benzo[1,2‐b:4,5‐b']dithiophene (BDT) as electron donors, were synthesized with Stille cross‐coupling reactions. The number‐averaged molecular weights (Mn) of PTSSO‐TT and PTSSO‐BDT were found to be 15100 and 26000 Da, with dispersity of 1.8 and 2.4, respectively. The band‐gap energies of PTSSO‐TT and PTSSO‐BDT are 1.56 and 1.59 eV, respectively. The HOMO levels of PTSSO‐TT and PTSSO‐BDT are ?5.4 and ?5.5 eV, respectively. These results indicate that the inclusion of TSSO accepting units into polymers is a very effective method for lowering their HOMO energy levels. The field‐effect mobilities of PTSSO‐TT and PTSSO‐BDT were determined to be 1.5 × 10?3 and 4.5 × 10?4 cm2 V?1 s?1, respectively. A polymer solar cell device prepared with PTSSO‐TT as the active layer was found to exhibit a power conversion efficiency (PCE) of 3.79% with an open circuit voltage of 0.71 V under AM 1.5 G (100 mW cm?2) conditions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 498–506  相似文献   

19.
Self-assembly of organic small molecules into an ordered thin film has been the key strategy towards efficient charge transport for organic field-effect transistors (OFETs). Solution processing is a feasible and economic way to enhance pi–pi interaction. Herein, nitrile-substituted unsymmetrical triarylamines for OFET applications with high mobility are reported. The compounds were constructed by Suzuki cross-coupling reactions under inert conditions. The HOMO level of about 5.3 eV indicates good hole-transporting ability. OFETs were assembled in bottom-gate, top-contact architecture. Devices fabricated from a binary solvent system exhibited excellent p-channel characteristics, with impressively high charge-carrier mobility of up to 2.58 cm2 V−1 s−1 and ION/OFF current ratios of 106–107. SEM and AFM analysis showed the efficient molecular self-assembly attained by the simple and effective solvent-engineering method. Theoretical insights obtained by DFT calculations supported by single-crystal structures showed that the crystalline nature and packing modes of these compounds ensure high mobility. The results prove that these compounds have great potential for use in numerous electronic applications, such as sensors and logic switches.  相似文献   

20.
We theoretically design four diaza‐benzo[k]tetraphene‐based diradical isomers ( 1, 2, 3 , and 4 ) with two nitroxide (NO) radical groups as spin sources. The calculations at the B3LYP/6‐311++G(d,p) level suggest that the diaza doping can induce the aromaticity changes and the C C bond rearrangements and, thus, remarkably affect their magnetic coupling magnitudes and even characteristics (ferromagnetic vs. antiferromagnetic). More interestingly, different diaza‐doping positions can lead to distinctly different effects, and further dielectron‐oxidation can also noticeably change the magnetic coupling magnitudes from −919.9 cm−1 ( 1 ) to −158.3 cm−1 ( 1 2+ ) or from −105.1 cm−1 ( 3 ) to −918.9 cm−1 ( 3 2+ ) or induce the magnetic conversions from nonmagnetism ( 2 ) to antiferromagnetism ( 2 2+ , −140.1 cm−1) or from ferromagnetism ( 4 , 108.9 cm−1) to antiferromagnetism ( 4 2+ , −462.5 cm−1). Good matching of two singly occupied molecular orbitals (SOMOs) of the NO groups with the highest occupied molecular orbital (HOMO) of the coupler (for 1 ), or with the lowest unoccupied molecular orbital (LUMO) of the coupler (for 3 2+ and 4 2+ ), available Kekulé structure (for 2 ), aromaticity variations are responsible to strong magnetic couplings. Besides, the HOMO‐LUMO energy gaps of the couplers also considerably affect the magnetic couplings. This work may open a new route for the rational design of the diaza‐benzo[k]tetraphene‐based magnetic molecular modulators or switches.  相似文献   

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