Synthesis and studies of blue light emitting polymers containing triphenylamine‐substituted fluorene and diphenylanthracene moiety

Photoluminescent (PL) polymers containing triphenylamine‐substituted fluorene and diphenylanthracene (DPA) units were synthesized by aromatic nucleophilic substitution reaction. The light emitting polymers (LEPs) contains hole‐transporting triphenylamine (TPA) groups at the C‐9 position of fluorene and DPA‐emitting segments in the main chain. The obtained polymers were soluble in various organic solvents and thermally stable. The synthesized polymers were successfully characterized by elemental analyses, FTIR and, ¹H NMR spectroscopy. The electrochemical measurements and optical properties of the polymers were also studied. The obtained polymers showed significant blue emission. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The interaction between conjugated polymer and fullerenes

The fluorescence of Poly(2-methoxy,5-(2′-ethylhexloxy)-p-phenylene-vinylene) (MEH–PPV) quenched by fullerenes was examined, and the results indicate that this quenching is not dynamic. Strong interaction in the excited state between them may be caused by the photoinduced charge transfer and π–π conjugated system interaction. More direct and convincing evidence of the charge transfer complex are presented. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 599–603, 1998     

Fast response single‐ion transport light‐emitting electrochemical cell based on PPV derivative

We present the electrical and optical characteristics of a single‐ion transport light‐emitting electrochemical cell (SLEC) based on poly(p‐phenylene vinylene) (PPV) derivative containing aryl‐substituted oxadiazole in the backbone (MEH‐OPPV). Ionized polyurethane–poly(ethylene glycol) (PUI) used as polymer electrolyte is introduced into the active layer of the SLEC. The turn‐on voltage of the SLEC is about 3 V according to its current density–voltage (J–V) characteristics. The response time of the SLEC is less than 10 ms, lower than that of normal LECs by two orders of magnitudes roughly. The reasons of the quick response for the SLEC are discussed in the article. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4253–4255, 2006     

发绿光醇酸树脂涂料的制备及其性质研究

合成了稀土铽配合物Tb(OPri)(acac)2,通过配合物中稀土铽离子与醇酸树脂涂料中的羰基发生配住作用后将铽离子引入到涂料中,制得了在紫外灯照射下可发绿光的醇酸树脂涂料.用紫外吸收光谱、红外吸收光谱、荧光光谱、原子力显微镜等分析手段研究了该发光涂料.研究表明,该稀土离子配合物能够与涂料发生配位,所得的涂料具有较好的光致发光性质.     

Synthesis and properties of novel deep red‐emitting copolymers based on a poly(p‐phenylenevinylene) derivative

A series of novel copolymers based on a poly(p‐phenylenevinylene) (PPV) derivative with different content of narrow band‐gap unit 2,1,3‐benzoselenadiazolevinylene (BSeV) was prepared via Stille coupling reaction. The copolymers emit light from deep red to near‐infrared (NIR) depending on BSeV content in the copolymers. The electroluminescence (EL) emission peaked at 752 nm for the copolymer with the content of 30 mol % BSeV is among the longest reported so far for the PPV polymers. The best device performance is observed for the copolymer with 1 mol % BSeV content with external quantum efficiency (QE_ext) of 0.26% and CIE coordinate 0.65, 0.34 (x,y). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4321–4327, 2006     

TPA‐PPEs – New alternating donor copolymers for potential application in photovoltaic devices

A series of phenyleneethynylene copolymers with triphenylamine units as hole‐transporting moieties (TPA‐PPEs) were synthesized by the palladium‐catalyzed cross‐coupling polycondensation of diethynyltriphenylamines and selected dihalogen comonomers, for instance substituted benzene, thiophene, benzothiadiazole, or anthracene. Incorporation of the electron‐rich amino group into the PPE backbone does not interrupt the main chain conjugation. Furthermore, it has a decreasing effect on the oxidation potential, thus makes these polymers interesting as hole‐injection/hole‐transporting materials. The chemical structure of the new alternating copolymers was confirmed by ¹H and ¹³C NMR spectroscopy and elemental analysis and gel‐permeation chromatography (GPC; THF, M_n ≈ 15,000–30,000 g/mol) was conducted. Furthermore, their optical properties were investigated by UV/vis spectroscopy. The TPA‐PPEs exhibit absorption maxima at around 400 nm (π‐π*), except anthracene containing copolymer 3f (λ_max = 514 nm in THF) and benzothiadiazole containing one 3g (λ_max = 503 nm in THF). The TPA copolymers have oxidation potentials about 1.1 V (Ag/AgCl). They are good photoconducting materials ( 3a : I_Photo = 4 × 10^?10 A at 425 nm (400 V), 3g : I_Photo = 1.3 × 10^?11 A at λ_max = 500 nm (20 V)) and show emission after excitation at around 450 nm (560 nm 3f ). Their application in nonoptimized polymer solar cells (bulk heterojunction) led to power conversion efficiencies of around 1–1.8% after illumination with 100 mW/cm² of AM1.5. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

New fluorene-based alternating copolymers with pendent N,N-diethylaniline group: Highly sensitive and selective detection for Hg with “Turn-on” fluorescence response

Two fluorene-based alternating copolymers P1 and P2 with the N,N-diethylaniline pendent group in different contents on the polymer backbone were synthesized through Suzuki Coupling Reaction, and were fully characterized by ¹H NMR, elemental analysis, and gel-permeation chromatography (GPC). Photophysical studies show that changes of the contents of the N,N-diethylaniline groups have little effect on the ground state electronic structure, but take a significant effect on the excited state. The intensities of green emission band in these polymers changes with the different content of diethylaniline groups, and are supposed to be originated from an intramolecular charge transfer process. Both of the P1 and P2 show remarkable fluorescence emission “turn-on” responses exclusively to Hg²⁺. Moreover, fluorescent titration experiments indicate that the two copolymers have high sensitivity for Hg²⁺. The coordination between metal ions and N atoms could greatly weaken the electron-donating ability of N atoms, consequently inhibit the intramolecular charge transfer process, leading to fluorescence emission enhancement. As far as we know, this is the first report for detection of Hg²⁺ with “turn-on” output signals based on polyfluorenes.     

Polymer electronic materials: a review of charge transport

This article presents an overview of the charge transport phenomenon in semiconducting polymer materials. In these disordered systems both intrinsic and extrinsic parameters play significant roles. In general, π‐electron delocalization, interchain interaction, band gap, carrier density, extent of disorder, morphology and processing of materials determine the electrical and optical properties. The chemical structure, especially the role of side groups, is quite important in both physical and processing properties. The nature of charge carriers and their role in charge transport depend on the structure and morphology of the system. Hence in several semiconducting polymer devices, the correlations among structure, morphology and transport are rather strong. The dependence of carrier mobility on temperature and electric field needs to be understood in the framework of competing models based on carrier hopping, trapping/detrapping and tunneling. Exactly what determines the dispersive/nondispersive, polaronic and correlative transport regimes is yet to be quantified. An understanding of the carrier mobility in semiconducting polymers is necessary to optimize the performance of polymeric electronic devices. Copyright © 2006 Society of Chemical Industry     

Synthesis of Two New Polyferrocenylsilanes and Magnetic Properties of Their Charge Transfer Complexes

Two polyferrocenylsilanes (PFSs) 1 and 2 with aniline and carbazolyl as side chains have been prepared by treating silyl-chloride functionalized PFS (PFS-Cl) with hydroxyl-ended aniline and carbazole compounds, respectively, and characterized by NMR, FT-IR, elemental analysis (EA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and cyclic voltammetry (CV). Both of them could be oxidized by iodine and 2,3-dichloro-5,6-dicyanoquinone (DDQ) to form complexes. PFS 1 could be oxidized by tetracyanoethylene (TCNE) too. The complexes are characterized by FT-IR, EA, Iron-57 Mössbauer spectroscopy. All of them are partially oxidized by the oxidants and both Fe^II and Fe^III coexist in the complexes. Magnetic property measurement by superconducting quantum interference device (SQUID) shows their paramagnetic properties with somewhat antiferromagnetic interaction. Results show that the joint type between PFS backbone and the electron-rich side groups has less direct effect on the exhibition of ferromagnetic interaction in their complexes.     

对苯醌与异烟肼的荷移反应及其应用研究

通过研究对苯醌与异烟肼之间的荷移反应建立了测定异烟肼的新方法。实验发现:以乙醇为溶剂,保持60℃温度,对苯醌与异烟肼混合30min能产生较为稳定的荷移络合物,络合物在最大吸收波长440nm处的吸光度值与异烟肼浓度在4.115~109.72mg·L-1浓度范围内呈良好的线性关系,线性方程为A=13.829C(mg·L-1)+0.3992(r=0.9962),方法应用于异烟肼片中异烟肼含量测定,回收率为97.6%~105.7%,测定值的相对标准偏差小于4.52%。     

Alternating phenylenevinylene copolymers with dithienbenzothiadiazole moieties: Synthesis,photophysical, and photovoltaic properties

Two new soluble alternating phenylenevinylene copolymers S and L which contained dithienbenzothiadiazole moieties were synthesized by Heck coupling. The repeating unit of L was longer than that of S and contained two additional phenylene rings and two cyano‐vinylene bonds. Both copolymers were stable up to about 350°C and afforded char yield of 52–66% at 800°C in N₂. Their absorption spectra were broad and extended up to about 600 nm with a longer wavelength maximum at 447–502 nm and optical band gap of ～ 2.0 eV. These copolymers emitted yellow light in solution with PL maximum at 551–580 nm and orange‐red light in thin film with PL maximum at 588–661 nm. The emission maximum of L was considerably red‐shifted relative to S . Photovoltaic cells based on S (or L ) as donor and [6,6]‐phenyl C61‐butyric acid methyl ester as acceptor were investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and photoconductive characteristics of biphenylporphyrin‐containing poly(amic acid)s and polyimides

Three series of biphenylporphyrin (BPP)‐containing poly(amic acid)s (PAAs) were synthesized and converted into heat‐treated polyimides (HPIs) and chemically treated polyimides (CPIs). Viscosity measurements, UV–vis and IR spectroscopies, as well as thermogravimetric analysis (TGA), were used to characterize the structures of the polymers. UV–vis spectra revealed that the BPP units formed aggregates in PAA and CPI films, rather than in HPI films. Photoinduced discharge was used to characterize the photoconductive properties of these polymer films. It was found that the photosensitivity was greatly enhanced by introducing BPP units into the polymer chains. For these three series of polymers, the photosensitivity increased in the order PAA < HPI < CPI according to the content of BPP in the polymers. The photoconductive characteristics were interpreted by the intrinsic π—π* process of BPP aggregation and the extrinsic process of charge‐transfer complex formation. The best photoconductive performances of the CPIs were attributed to the existence of two charge‐carrier‐generation processes. Copyright © 2004 Society of Chemical Industry     

A polythiophene derivative with dioctyloxyltriphenylamine‐vinylene conjugated side chain: Synthesis,hole mobility,and photovoltaic property

A new polythiophene derivative with dioctyloxyl triphenylamine‐vinylene ( DOTPAV ) conjugated side‐chain, DOTPAV‐PT , was synthesized by the Stille coupling method and characterized by ¹H‐NMR, ¹³C‐NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, UV–vis absorption spectroscopy, photoluminescence spectroscopy, and cyclic voltammetry. The polymer DOTPAV‐PT is soluble in common organic solvents and possesses good thermal stability with 5% weight loss temperature of 310°C. The weight‐average molecular weight of DOTPAV‐PT is 8.0 K with a polydispersity index of 1.24. The hole mobility of the polymer determined from space‐charge‐limited current model was 1.25 × 10^?4 cm² V^?1 s^?1. The bulk heterojunction polymer solar cell with the configuration of ITO/PEDOT : PSS/polymer : PCBM (1 : 1)/Ca/Al was fabricated, and the power conversion efficiency of the device was 0.16% under the illumination of AM1.5, 100 mW cm^?2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Amphiphilic block copolymers bearing strong push-pull azo chromophores: Synthesis, micelle formation and photoinduced shape deformation

In this work, a series of amphiphilic diblock copolymers bearing strong push-pull type azo chromophores was synthesized through post-polymerization azo-coupling reaction scheme. The copolymers (P(CNAZO_m-b-MAA_n)), composed of 2-(N-ethyl-N-(4-(4′-cyanophenylazo)-phenyl)amino)ethyl methacrylate (CNAZO) and methacrylic acid (MAA) blocks, were obtained through four-step reactions. Firstly, precursor diblock copolymers (P(EMA_m-b-tBMA_n)) were obtained through sequential two-stage ATRP reactions of 2-(N-ethyl-N-phenylamino)ethyl methacrylate (EMA) and tert-butyl methacrylate (tBMA). Then, 4-amino-4′-cyanoazobenzene chromophores were introduced by azo-coupling reaction of P(EMA_m-b-tBMA_n) with diazonium salt of 4-aminobenzonitrile. Finally, P(CNAZO_m-b-MAA_n) was obtained through selective hydrolysis of the tert-butyl ester linkages in the tBMA blocks. Three block copolymers with the same CNAZO block length (m = 100) and different MAA block lengths (n = 5, 13, 23) were prepared by this method. The polymer and copolymers prepared in the process were characterized by GPC, ¹H NMR, UV-vis, DSC and TGA measurements. Results show that P(CNAZO_m-b-MAA_n) forms spherical micellar aggregates by gradually increasing the water content in THF/H₂O mixtures. The diameters of the spherical aggregates are related to the composition of the block copolymers and the water-adding rate. The block copolymer with larger molecular weight of the hydrophilic MAA block forms the aggregates with the smaller average size. The increase of the water-adding rate also shows an effect to reduce the diameters. Upon irradiation with a linearly polarized Ar⁺ laser beam, the spherical aggregates can be elongated in the light polarization direction. The deformation degree shows an almost linear dependence on the light irradiation time in the testing period. The deformed aggregates can recover the original spherical shape after thermal annealing at a temperature above T_g of the block copolymer.     

Organic light emitting bistable memory device with Cs doped electron transport layer

Dual functional organic light emitting bistable memory devices (OLEBDs) were developed by using a Cs doped electron transport layer. Bistability was exhibited by Cs doping in 4,7-diphenyl-1,10-phenanthroline (Bphen) and the driving voltage was lowered by alkali metal doping. n-type doping effect of Cs with Bphen induced the electrical switching behavior in OLEBDs and a low driving voltage. A high on/off ratio over 1000 could be obtained in Cs doped OLEBDs and it was kept stable during multicycle measurements. OLEBDs showed superior performances both as a memory and a light emitting device.     

Dielectric constant and loss investigations of pristine,iodine‐doped and annealed polyetherimide film

Temperature‐ and frequency‐dependent dielectric behaviour has been investigated for pristine, iodine‐doped and annealed polyetherimide (PEI) in the temperature range 303–523 K at various frequencies (120 Hz, 1 kHz, 10 kHz and 100 kHz). In pristine PEI, the rapid decrease in the dielectric constant (ε′) in the temperature range 303–373 K is governed by the Kirkwood model whereas the gradual decrease in ε′ in the temperature range 373–473 K is governed by β‐relaxation (dipolar) and αβ‐relaxation (hybrid) processes. The occurrence of these relaxations is confirmed by the appearance of tan δ loss peaks at ca 403 and 443 K, respectively, in ε″–T curves. The temperature‐independence of ε′ in the temperature range 473–523 K is mainly governed by the α‐relaxation process associated with large segmental groups. The tan δ loss peak appearing at 503 K confirms this relaxation process. In iodine‐doped samples, an overall increase in ε′ is attributed to the formation of charge‐transfer complexes in the polymer structure. The dominance of a new relaxation process due to interaction of iodine with ether linkages neutralizes the 1/T rule in the low‐temperature region. A significant decrease in ε′ in annealed samples below 393 K is due to the suppression of the dipolar relaxation process. The enhancement in ε′ above 393 K is due to the dominance of the α‐relaxation process. The shift in the high‐temperature tan δ loss peak towards higher temperature with increasing frequency shows the distributive nature of relaxation time for this relaxation process. Copyright © 2011 Society of Chemical Industry     

Photoinitiated alternating copolymerization of vinyl ethers with chlorotrifluoroethylene

The photoinitiated copolymerization of chlorotrifluoroethylene (CTFE) with several vinyl ethers [ethyl vinyl ether (EVE), 2‐chloroethyl vinyl ether (CEVE), cyclohexyl vinyl ether (CHVE), 4‐hydroxybutyl vinyl ether (HBVE)] was studied. CTFE is an acceptor monomer (e ～ 1.5) whereas vinyl ethers are donor monomers (e ～ ?1.5), and therefore their copolymerization led to alternating copolymers, as indicated by elementary analysis. The equilibrium constant (K_F) of the charge‐transfer complex formation (CTC) was determined by ¹⁹F NMR spectroscopy. Under our experimental conditions, K_F was low for CHVE/CTFE and HBVE/CTFE systems, 0.058 and 0.013 l mol^?1 respectively. It can be assumed that the copolymerization involves the free monomers rather than propagation via the donor–acceptor complex. The alternating structure arises from the great difference in polarity between the two types of monomers. Several functional copolymers were prepared in good yield and with molecular weight close to 15 000 g mol^?1. © 2002 Society of Chemical Industry     

Synthesis and characterization of fluorene-carbazole and fluorene-phenothiazine copolymers with carbazole and oxadiazole pendants for organic light emitting diodes

We report the synthesis and characterization of new series of the fluorene based polymers with carbazole and oxadiazole pendants for the generation of the white emission out of the EL device. In the fluorene backbone, hole transporting units such as carbazole or phenothiazine were incorporated to improve the EL brightness and efficiency. The PFCzOxd-co-PCzs and PFCzOxd-co-PPTZs in EL spectra showed maximum peaks at around 430 nm and additional large peaks at around 530 and 500 nm, respectively. In case of PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz, the EL spectra of the polymers showed two distinct peaks comprising the maximum at 427 nm, which corresponds to the EL spectra of the conjugated backbone, and additional broad peaks at around 540 and 530 nm, respectively. The CIE coordinates of the devices from PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz were (0.28, 0.33) and (0.25, 0.32), respectively, approaching the value of the standard white of National Television System Committee (NTSC) (0.33, 0.33).     

Synthesis and electroluminescent properties of copolymers based on PPV with fluoro groups in vinylene units

New electroluminescent copolymers with fluoro groups in vinylene unit, poly(2-ethylhexyloxy-5-methoxy-p-phenylenevinylene-co-2-dimethyloctylsilyl-p-phenylenedifluorovinylene) (MEH-PPV-co-DMOS-PPDFV) and poly(2-dimethyloctylsilyl-p-phenylenevinylene-co-2-dimethyloctylsilyl-p-phenylenedifluorovinylene) (DMOS-PPV-co-DMOS-PPDFV), have been synthesized by the Gilch polymerization. The fluoro groups were introduced on vinylene units to increase the electron affinity of the copolymers. In both types of the copolymers, the band gaps were increasing with higher ratio of DMOS-PPDFV. As compared to the PL spectra in solution state, PL spectra in solid state and EL spectra of both types of copolymers showed red shifted and broad peaks caused by the aggregation. The polymer LEDs of MEH-PPV-co-DMOS-PPDFVs emit light with maximum peaks at around 538-577 nm. By adjusting the feed ratios of DMOS-PPDFV in the copolymers, we could tune the emission colors from orange yellow to green. DMOS-PPV-co-DMOS-PPDFVs showed the maximum EL peaks at about 514-543 nm. DMOS-PPV-co-DMOS-PPDFV with 1:9 feed ratio showed the highest luminescence efficiency of 1.31 lm/W.     

Alternating block copolymers based on polyamide‐12 and polycaprolactone

A series of alternating polyester/polyamide block copolymers were prepared by sequential conversion of hydroxy‐terminated polycaprolactone and amino‐terminated polyamide‐12 with a selectively reacting coupling agent. The thermal properties of the block copolymers were investigated using differential scanning calorimetry and dynamic mechanical analysis. Mechanical properties were determined using tensile and impact tests. All polymers were phase‐separated, where the polyamide phase was semicrystalline in all compositions. Distinct crystallization of the polycaprolactone phase was observed only when the block length was greater than 2000 g mol^?1. Mechanical testing showed that the polymers behave in a manner similar to that of thermoplastic elastomers. In particular, samples with a high content of polycaprolactone showed high strain and good impact behaviour. Copyright © 2011 Society of Chemical Industry