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1.
A strategy of the fine‐tuning of the degree of intrachain charge transfer and aromaticity of polymer backbone was adopted to design and synthesize new polymers applicable in photovoltaics. Three conjugated polymers P1 , P2 , and P3 were synthesized by alternating the electron‐donating dithieno[3,2‐b:2′3′‐d]pyrrole (D) and three different electron‐accepting (A) segments ( P1 : N‐(2‐ethylhexyl)phthalimide; P2 : 1,4‐diketo‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole; and P3 : thiophene‐3‐hexyl formate) in the polymer main chain. Among the three polymers, P2 possessed the broadest absorption band ranging from 300 to 760 nm, the lowest bandgap (1.63 eV), and enough low HOMO energy level (?5.27 eV) because of the strong intrachain charge transfer from D to A units and the appropriate extent of quinoid state in the main chain of P2 , which was convinced by the theoretical simulation of molecular geometry and front orbits. Photovoltaic study of solar cells based on the blends of P1 – P3 and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) demonstrated that P2 :PCBM exhibited the best performance: a power conversion efficiency of 1.22% with a high open‐circuit voltage (VOC) of 0.70 V and a large short‐circuit current (ISC) of 5.02 mA/cm2 were achieved. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

2.
A new series of stable, processable, and chain end functionalizable sulfone‐derivatized phenylenevinylene‐based conjugated polymers (SFPVs) containing different donor type comonomers have been synthesized and characterized. The polymer main chains are consisted of a sulfone‐phenylene electron accepting unit coupled with an electron donating unit which is derived from one of the dialdehyde comonomers based on benzene, thiophene, and pyrrole (with or without alkoxy side chains). The optical energy gaps (Eg) of the new polymers (in solvent) are in a range of 1.9–2.3 eV, with the lowest energy gap obtained from the polymer containing pyrrole as the donor unit. By using a combination of strong donor unit (such as pyrrole) and a relatively weak but stable acceptor unit (sulfone‐substituted benzene), Eg of the conjugated polymers can be tailored to below 2 eV, while the vinylene bonds on the polymer main chain are still chemically stable to survive strong basic conditions as compared with the S,S‐dioxo‐thiophene‐based PTV polymers developed earlier for potential supra‐molecular block copolymer systems. The lowest energy gap P(Pyrrole‐SFPV) exhibited 10 times better photoelectric power conversion efficiency than P(TV‐SFPV). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

3.
Six alternating conjugated copolymers ( PL1 – PL6 ) of benzo[1,2‐b:4,5‐b′]dithiophene (BDT) and thiophene, containing electron‐withdrawing oxadiazole (OXD), ester, or alkyl as side chains, were synthesized by Stille coupling reaction. The structures of the polymers were confirmed, and their thermal, optical, electrochemical, and photovoltaic properties were investigated. The introduction of conjugated electron‐withdrawing OXD or formate ester side chain benefits to decrease the bandgaps of the polymers and improve the photovoltaic performance due to the low steric hindrance of BDT. Bulk heterojunction polymer solar cells (PSCs) were fabricated based on the blend of the as‐synthesized polymers and the fullerene derivative [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) in a 1:2 weight ratio. The maximum power conversion efficiency of 2.06% was obtained for PL5 ‐based PSC under the illumination of AM 1.5, 100 mW/cm2. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

4.
In an effort to design efficient low‐cost polymers for use in organic photovoltaic cells the easily prepared donor–acceptor–donor triad of a either cis‐benzobisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole flanked by two thiophene rings was combined with the electron‐rich 4,8‐bis(5‐(2‐ethylhexyl)‐thien‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene. The electrochemical, optical, morphological, charge transport, and photovoltaic properties of the resulting terpolymers were investigated. Although the polymers differed in the arrangement and/or nature of the chalcogens, they all had similar highest occupied molecular orbital energy levels (?5.2 to ?5.3 eV) and optical band gaps (2.1–2.2 eV). However, the lowest unoccupied molecular orbital energy levels ranged from ?3.1 to ?3.5 eV. When the polymers were used as electron donors in bulk heterojunction photovoltaic devices with PC71BM ([6,6]‐phenyl C71‐butyric acid methyl ester) as the acceptor, the trans‐benzobisoxazole polymer had the best performance with a power conversion efficiency of 2.8%. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 316–324  相似文献   

5.
Here, a family of donor/acceptor (D/A) alternating copolymers and random two‐acceptor and three‐acceptor copolymers were synthesized via Suzuki polymerization based on heptadecan‐9‐yl substituted carbazole as a donor and 4,7‐Bis(5‐bromothiophene‐2‐yl)benzo[c][1,2,5]thiadiazole (DTBT), 2,5‐diethylhexyl‐3,6‐bis(5‐bromothiophene‐2‐yl)pyrrolo[3,4‐c]‐pyrrole‐1,4‐dione (DPP) and 2,8‐dibromo‐4,10‐bis(2‐ethylhexyl)thieno[2′,3′:5,6] pyrido[3,4‐g]thieno[3,2‐c]isoquinoline‐5,11(4H,10H)‐dione (TPTI) as acceptors. For the first time, a relatively new electron‐deficient TPTI unit was used as an acceptor in carbazole‐based conjugated polymers. Introduction of the electron‐deficient TPTI unit into the polymer backbone increased the open‐circuit voltage (Voc) of the resulting polymer solar cells up to 0.96 V. PCTPTI and PCDTBT‐TPTI exhibited external quantum efficiencies (EQE) up to 75%. All random two‐acceptor copolymers showed broadened absorption profiles compared to the D/A alternating analogues. In order to further improve the light absorption, a random three‐acceptor copolymer was synthesized for the first time, resulting in the broadest absorption in the range of 350–750 nm. Highest occupied molecular orbital (HOMO) energies and Voc values of the resulting polymers could be successfully tuned by introducing different monomer units into the polymer backbone in different ratios. These results indicate that TPTI is a promising acceptor unit for conjugated polymers and that the random copolymer approach is a successful tool for fine tuning of polymer properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2781–2786  相似文献   

6.
Novel polyfluorene copolymers alternately having an 1,3,4‐oxadiazole unit in the main chain were prepared by both one‐step and two‐step methods for polyoxadiazole synthesis. They displayed highly efficient blue photoluminescence, the properties of which were affected by the extent of conjugation and the changes in the electron density by a side chain. An electrochemical analysis of the polymers using cyclic voltammetry suggested that they could be used as electron‐transport/hole‐blocking materials as well as blue emission materials for polymer light‐emitting diodes. A simple double‐layer device consisting of poly(N‐vinylcarbazole) as a hole‐transport layer and poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐((1,4‐bis(1,3,4‐oxadiazole)‐2,5‐di(2‐ethylhexyloxy)phenylene)‐5,5′‐diyl)] as an emission layer exhibited narrow blue electroluminescence with a maximum at 430 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1058–1068, 2004  相似文献   

7.
Starting from the pyrylium salt and following a facile synthetic route, we synthesized and polymerized 4,4″‐diiodo‐2′,6′‐di[4‐(2′‐ethylhexyl)oxy]phenyl‐p‐terphenyl with p‐divinylbenzene or p‐diethynylbenzene. The resulting polymers had moderate molecular weights, were amorphous, and dissolved in tetrahydrofuran and chloroform, with glass‐transition temperatures of 120–131 °C. The polymers behaved as violet‐blue‐emitting materials with photoluminescence maxima around 420 and 450 nm in solution and in thin films, respectively. They possessed well‐defined chromophores resulting from steric interactions in the polymer chain. The photoluminescence quantum yields were up to 0.29. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2591–2600, 2002  相似文献   

8.
Mesogen‐jacketed liquid crystalline polymers (MJLCPs) with both electron‐transport oxadiazole and hole‐transport thiophene in the side chain were reported for their promising electroluminescent property. Monomers of 2,5‐bis{5‐[(4‐alkoxyphenyl)‐1,3,4‐oxadiazole]thiophen‐2‐yl}styrene (M‐Cm, m is the number of the carbons in the alkoxy groups, m = 8,10) were synthesized and confirmed by 1H‐NMR, mass spectrometry, and elemental analysis. The corresponding polymers were successfully obtained and characterized by thermal analysis, optical spectroscopy, cyclic voltammetry, electroluminescent analysis, polarized light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD). The polymers exhibited high decomposition temperatures reaching 382 °C and high Tg's reaching 184 °C. The absorption spectra indicated that both the monomers and polymers had little aggregation in film than that in solution, and the absorption spectra of the polymers showed an obvious blue‐shift compared with those of the monomers. Both the monomers and the polymers had blue‐green emission, and the photoluminescence spectra of the polymers in film suggested the formation of excimer or exciplex. The polymers showed lower HOMO energy levels and LUMO energy levels than those of the MJLCPs containing oxadiazole unit reported before. Electroluminescence study with the device configuration of ITO/PEDOT/PVK/polymer/TPBI/Ca/Ag showed maximum brightness and current efficiency of 541 cd/m2 and 0.10 cd/A, which proved that the introduction of directly connected electron‐ and hole‐transport units could greatly improve the EL property of side‐chain conjugated polymers. The phase structures of the polymers were confirmed to be smectic A phase through the results of PLM and WAXD. The annealed samples emitted polarized photoluminescence at room temperature, which indicated potential utility for practical applications in display. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1502–1515, 2010  相似文献   

9.
To explore the aptitude of 1,2,4‐oxadiazole‐based electron‐acceptor unit in polymer solar cell applications, we prepared four new polymers (P1–P4) containing 1,2,4‐oxadiazole moiety in their main chain and applied them to solar cell applications. Thermal, optical, and electrochemical properties of the polymers were studied using thermogravimetric, absorption, and cyclic voltammetry analysis, respectively. All four polymers showed high thermal stability (5% degradation temperature over 335 °C), and the optical band gaps were calculated to be 2.20, 1.72, 1.37, and 1.74 eV, respectively, from the onset wavelength of the film‐state absorption band. The energy levels of the polymers were found to be suitable for bulk heterojunction (BHJ) solar cell applications. The BHJ solar cells were prepared by using the synthesized polymers as a donor and PC71BM as an electron acceptor with the configuration of ITO/PEDOT:PSS/polymer:PC71BM (1:3 wt %)/LiF/Al. One of the polymers was found to show the maximum power conversion efficiency of 1.33% with a Jsc of 4.95 mA/cm2, a Voc of 0.68 V, and a FF of 40%, measured using AM 1.5 G solar simulator at 100 mW/cm2 light illumination. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013  相似文献   

10.
Sodium salts of water‐soluble polymers poly{[2,5‐bis(3‐sulfonatopropoxy)‐1,4‐phenylene]‐alt‐[2,5‐bis(hexyloxy)‐1,4‐phenylene]} ( P1 ), poly{[2,5‐bis(3‐sulfonatopropoxy)‐1,4‐phenylene]‐alt‐[2,5‐bis(dodecyloxy)‐1,4‐phenylene]} ( P2 ), poly{[2,5‐bis(3‐sulfonatopropoxy)‐1,4‐phenylene]‐alt‐[2,5‐bis(dibenzyloxy)‐1,4‐phenylene]} ( P3 ), poly[2‐hexyloxy‐5‐(3‐sulfonatopropoxy)‐1,4‐phenylene] ( P4 ), and poly[2‐dodecyloxy‐5‐(3‐sulfonatopropoxy)‐1,4‐phenylene] ( P5 )] were synthesized with Suzuki coupling reactions and fully characterized. The first group of polymers ( P1 – P3 ) with symmetric structures gave lower absorption maxima [maximum absorption wavelength (λmax) = 296–305 nm] and emission maxima [maximum emission wavelength (λem) = 361–398 nm] than asymmetric polymers P4 (λmax = 329 nm, λem = 399 nm) and P5 (λmax = 335 nm, λem = 401 nm). The aggregation properties of polymers P1 – P5 in different solvent mixtures were investigated, and their influence on the optical properties was examined in detail. Dynamic light scattering studies of the aggregation behavior of polymer P1 in solvents indicated the presence of aggregated species of various sizes ranging from 80 to 800 nm. The presence of alkoxy groups and 3‐sulfonatopropoxy groups on adjacent phenylene rings along the polymer backbone of the first set hindered the optimization of nonpolar interactions. The alkyl chain crystallization on one side of the polymer chain and the polar interactions on the other side allowed the polymers ( P4 and P5 ) to form a lamellar structure in the polymer lattice. Significant quenching of the polymer fluorescence upon the addition of positively charged viologen derivatives or cytochrome‐C was also observed. The quenching effect on the polymer fluorescence confirmed that the newly synthesized polymers could be used in the fabrication of biological and chemical sensors. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3763–3777, 2006  相似文献   

11.
We demonstrated, for the first time, that 3,6‐bis(3‐hexylthien‐2‐yl)‐s‐tetrazine (TTz) with hexyl group at the 3‐position of thiophene rings can be prepared using a modified sulfur‐assisted Pinner synthesis. Although the hexyl group creates large steric hindrance to the tetrazine ring formation reaction, and the reaction under a traditional condition only produces trace amount of the target product, the yield of this reaction under a modified reaction condition using anhydrous hydrazine at 68 °C can reach 65%. Two new copolymers of the resulting TTz and hexyl‐ or 2‐ethylhexyl‐substituted cyclepentadithiophene have been prepared. The polymers show a broader light absorption in film than in solution attributing to the large distribution of effective conjugation length of polymer chain due to the existence of both cis‐ and trans‐orientations of the 3‐hexylthiophene units in the planar polymer chain in solid state. Although the polymers show a narrow band gap and a deep HOMO level, which are desirable for generating an efficient light absorption and a larger open circuit voltage (Voc) of the resulting solar cell devices, the device performance is not as good as expected. It is attributed to the random distribution of the cis‐ and trans‐conformations along the polymer chain. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.  相似文献   

12.
A novel series of well‐defined alternating poly[2,7‐(9,9‐dihexylfluorenyl)‐alt‐pyridinyl] (PDHFP) with donor‐acceptor repeat units were synthesized using palladium (0)‐catalyzed Suzuki cross‐coupling reactions in good to high yields. In this series of alternating polymers, 2, 7‐(9,9‐dihexylfluorenyl) was used as the light emitting unit, and the electron deficient pyridinyl unit was employed to provide improved electron transportation. These polymers were characterized by 1H‐NMR and 13C‐NMR, gel permeation chromatography (GPC), thermal analyses, and UV‐vis and fluorescence spectroscopy. The glass transition temperature of copolymers in nitrogen ranged from 110 to 148 °C, and the copolymers showed high thermal stabilities with high decomposition temperatures in the range of 350 to 390 °C in air. The difference in linkage position of pyridinyl unit in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film phases. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable to polymer for pure blue emission and prevention of aggregation of polymer chain than para‐linkage (2,5‐linkage) of the pyridinyl units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4792–4801, 2004  相似文献   

13.
Reversible addition‐fragmentation chain transfer (RAFT) polymerization is a more robust and versatile approach than other living free radical polymerization methods, providing a reactive thiocarbonylthio end group. A series of well‐defined star diblock [poly(ε‐caprolactone)‐b‐poly(N‐isopropylacrylamide)]4 (SPCLNIP) copolymers were synthesized by R‐RAFT polymerization of N‐isopropylacrylamide (NIPAAm) using [PCL‐DDAT]4 (SPCL‐DDAT) as a star macro‐RAFT agent (DDAT: S‐1‐dodecyl‐S′‐(α, α′‐dimethyl‐α″‐acetic acid) trithiocarbonate). The R‐RAFT polymerization showed a controlled/“living” character, proceeding with pseudo‐first‐order kinetics. All these star polymers with different molecular weights exhibited narrow molecular weight distributions of less than 1.2. The effect of polymerization temperature and molecular weight of the star macro‐RAFT agent on the polymerization kinetics of NIPAAm monomers was also addressed. Hardly any radical–radical coupling by‐products were detected, while linear side products were kept to a minimum by careful control over polymerization conditions. The trithiocarbonate groups were transferred to polymer chain ends by R‐RAFT polymerization, providing potential possibility of further modification by thiocarbonylthio chemistry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

14.
We have synthesized six p‐type copolymers, CPDT ‐ co ‐ TPADCN , CPDT ‐ co ‐ TPADTA , CPDT ‐ co ‐ TPATCN , CPDT ‐ co ‐ DFADCN , CPDT ‐ co ‐ DFADTA , and CPDT ‐ co ‐ DFATCN , consisting of a cyclopenta[2,1‐b:3,4‐b′]dithiophene (CPDT) unit and an organic dye in an alternating arrangement. Triphenylamine (TPA) or difluorenylphenyl amine (DFA) units serve as the electron donors, whereas dicyanovinyl (DCN), 1,3‐diethyl‐2‐thiobarbituric acid, or tricyanovinyl (TCN) units act as the electron acceptors in the dyes. The target polymers were prepared via Stille coupling, followed by postfunctionalization to introduce the electron acceptors to the side chains. Because of the strongest withdrawing ability of TCN acceptor to induce efficient intramolecular charge transfer, CPDT ‐ co ‐ TPATCN and CPDT ‐ co ‐ DFATCN exhibit the broader absorption spectra covering from 400 to 900 nm and the narrower optical band gaps of 1.34 eV. However, the CPDT ‐ co ‐ TPATCN :PC71BM and CPDT ‐ co ‐ DFATCN :PC71BM based solar cells showed the power conversion efficiencies (PCEs) of 0.22 and 0.31%, respectively, due to the inefficient exciton dissociation. The DFA‐based polymers possess deeper‐lying HOMO energy levels than the TPA‐based polymer analogues, leading to the higher Voc values and better efficiencies. The device based on CPDT ‐ co ‐ DFADTA :PC71BM blend achieved the best PCE of 1.38% with a Voc of 0.7 V, a Jsc of 4.57 mA/cm2, and a fill factor of 0.43. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

15.
Four polythiophene derivatives including regiorandom polymers P1 , P2 , and P3 and a regioregular polymer P4 , containing a phenyl side chain with electron‐withdrawing carbonyl groups such as an ester and a ketone at the 3‐position of the thiophene ring, were synthesized by Stille coupling reaction. Bulk‐heterojunction polymer solar cells (PSCs) based on these polymers as p‐type semiconductors and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) were fabricated, and their photovoltaic performances were evaluated for the first time. The PSC devices based on the regioregular polymer P4 :PCBM = 1:2 (w/w) exhibited a high‐open‐circuit voltage (Voc) of 0.943 V because of the low‐lying highest occupied molecular orbit energy level of P4 . The short π–π stacking distance (0.355 nm) in the parallel direction to the substrate and “face‐on” rich orientation were observed by the grazing incidence wide‐angle X‐ray scattering experiment, which might reflect higher Jsc and FF values of the P4 :[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) PSC device than others. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 875–887  相似文献   

16.
A series of novel low band gap polymers containing conjugated side chains with 4,7‐dithien‐5‐yl‐2,1,3‐benzodiathiazole and different electron‐withdrawing end groups of aldehyde ( PT‐DTBTCHO ), 2‐ethylhexyl cyanoacetate ( PT‐DTBTCN ), 1,3‐diethyl‐2‐thiobarbituric acid ( PT‐DTBTDT ), and electron‐donating end group of 2‐methylthiophene ( PT‐DTBTMT ) have been designed and synthesized. All polymers exhibit good solubility in common organic solvents, film‐forming ability, and thermal stability. These conjugated polymers show the broad ultraviolet‐visible absorption and the narrow optical band gaps in the range of 1.65–1.90 eV. Through changing the end group of conjugated side chains, the photophysical properties and energy levels of the polymers were tuned effectively. Bulk heterojunction solar cells based on the blend of these polymers and (6,6)‐phenyl‐C61‐butyric acid methyl ester (PC61BM) reached the best power conversion efficiency (PCE) of 2.72%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

17.
A soluble charge‐transfer type poly(aryleneethynylene), PAE‐AzaBzTdz , consisting of a highly electron‐accepting azabenzothiadiazole unit was prepared in 99% yield by palladium‐catalyzed polycondensation between 4,7‐dibromo‐2,1,3‐azabenzothiadiazole ( Br2‐AzaBzTdz ) and 1,4‐diethynyl‐2,5‐didodecyloxybenzene. PAE‐AzaBzTdz showed a number‐average molecular weight, Mn, of 6000 in gel‐permeation chromatography analysis and had good thermal stability as measured by TGA. UV–vis spectrum of PAE‐AzaBzTdz exhibited an absorption peak at 529 nm in chloroform, and the absorption peak shifted to a longer wavelength (601 nm) in film. Addition of MeOH to a CHCl3 solution of PAE‐AzaBzTdz led to aggregation of the polymer to form stable colloidal particles. Results of filtration experiments using 0.2 and 0.02 μm membranes supported aggregation of the polymer. Addition of trifluoroacetic acid (TFA) to a chloroform solution of PAE‐AzaBzTdz led to a red‐shift of the UV–vis peak from 529 to 640 nm. An X‐ray diffraction pattern of powdery PAE‐AzaBzTdz indicated that the polymer assumed a layer‐to‐layer stacked structure with an interlayer distance of 3.4 Å in the solid state. An X‐ray diffraction pattern of cast film of PAE‐AzaBzTdz revealed that the polymer molecules in the cast film were ordered on the surface of Pt plate with the dodecyl side chain oriented toward the surface of the Pt plate. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2975–2982, 2008  相似文献   

18.
Hyperbranched organic–inorganic hybrid conjugated polymers P1 and P2 were prepared via FeCl3‐oxiditive polymerization of 4,7‐bis(3‐ethylhexyl‐2‐thienyl)‐2,1,3‐benzothiadiazole ( A ) and octa(3‐ethylhexyl‐2‐thienyl‐phenyl)polyhedral oligomeric silsesquioxane (POSS) ( B ) at different POSS concentrations. Compared to linear polymer PM derived from A , P1 , and P2 exhibit much higher PL quantum efficiency (?PL‐f) in condensed state with improved thermal stability. ?PL‐f of P1 and P2 increased by 80% and 400%, and the thermal degradation temperatures of P1 and P2 are increased by 35 °C and 46 °C, respectively. Light‐emitting diodes were fabricated using P1 , P2 , and PM . While the electroluminescent spectra of both P1 and PM show λmax at 660 nm, P1 exhibits a much narrower EL spectrum and higher electroluminescence (~500%) compared with PM at a same voltage and film thickness. The maximum current efficiency of P1 is more than seven times of that of PM . The turn‐on voltages of the LEDs are in the order of P2 > PM > P1 . LED prepared by blending P1 with MEH‐PPV shows a maximum luminescence of 2.6 × 103 cd/m2 and a current efficiency of 1.40 cd/A, which are more than twice (1.1 × 103 cd/m2) and five times (0.27 cd/A) of LED of PM /MEH‐PPV blend, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5661–5670, 2009  相似文献   

19.
Conducting polymers demonstrate low solubility in organic solvents. Introducing aliphatic substituents into polymer chains improves their solubility, but may also lead to changes in conformational characteristics of macromolecules. In the present work, the studies of hydrodynamic properties and conformational characteristics of comb‐shaped poly(3‐hexylthiophene) with aliphatic side substituents were carried out in chloroform solutions. Conformational analysis of the studied macromolecules was performed for the first time using homologous series with a wide range of molecular weights of the polymers in dilute solutions. The hydrodynamic properties of these macromolecules were interpreted using the worm‐like spherocylinder model and the straight spherocylinder model. The projection of the monomer unit in the direction of the main polymer chain λ = 0.37 nm was determined experimentally. The following parameters of poly(3‐hexylthiophene) were characterized and quantified: equilibrium rigidity (Kuhn segment length) А = 6.7 nm and hydrodynamic diameter of a polymer chain d = 0.6 nm. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 875–883  相似文献   

20.
Azobenzene monomeric precursors bearing piperazine as donor moiety with different withdrawing groups and derived side chain polymethacrylates have been prepared and characterized. Monomers having terminal cyano or nitro groups, and the corresponding polymers, exhibited smectic A phases. Linear and nonlinear optical properties of every monomer and thin films of the cyano polymer ( pol‐PZ‐CN ) have been also studied. UV‐vis spectroscopy revealed out‐of‐plane orientation in the as prepared films, as confirmed by waveguide refractive index measurements. Moreover, absorption spectra indicated the presence of azo aggregates in these films. The initial molecular arrangement has been modified by applying thermal annealing within the mesophase range and UV‐blue irradiation. Although thermal annealing resulted in a significant amplification of the out‐of‐plane optical anisotropy due to thermotropic self‐organization of side chain azo moieties, irradiation with 440 nm light induced some disruption of aggregates. The nonlinear optical response of Corona poled films has been studied by second harmonic generation measurements, and the influence of the molecular arrangement on the nonlinear dij coefficients has been analyzed. The more efficient poling corresponded to preirradiated films. In any case, a noticeable degree of polar order (70% of the initial d33 value) remained for several months after the poling in films kept at RT. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 232–242, 2010  相似文献   

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