Semiconducting polymers based on charge-transfer complexes. IV. Electrical properties and structure of polymeric charge-transfer complexes

Model electron donor molecules, 10-methylphenothiazine and 4-(methylthio)anisole, and polymeric electron donors which contained these molecules on the side chains of N-acyl-substituted polyethylenimines, were complexed with the electron acceptors, dichlorodicyanoquinone (DDQ), tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), and tetranitrofluorenone (TNF). The model donors formed 1:1 complexes with all the acceptors except TCNE. The polymeric donors formed amorphous complexes with DDQ, TCNQ, and TCNE. Crystalline complexes were formed with TNF which had low melting points (lower than the model complexes and the pure polymer). This is apparently due to poor lateral packing of the polymer chains. Electrical resistivities were lower for all the polymer complexes than for the corresponding model complexes. Electrical resistivity also decreased with increase in complex crystallinity. In the best case the polymer complex was two hundred times as conducting as the model. The concentration of unpaired electrons measured by EPR was nearly independent of temperature. Most of the electrons seen are trapped and do not participate in conduction. Thermal activation energies for conduction were in the range of 0.5–1.8 eV and were nearly equal for the model and corresponding polymeric complexes. Elongation of polymer complex with TCNQ by rolling produces a decrease in resistivity in the roll direction, although the complex is amorphous. This reinforces the hypothesis that conduction is parallel to the polymer backbone. A polymer–tetranitrofluorenone complex was photoconducting, though the photoconductivity was smaller than the dark conductivity at the level of illumination used. Dember and Seebeck effects indicated that the major carrier in the complex was holes.     

过渡金属吡啶配离子的TCNQ电荷转移盐的合成和物理性质

合成了通式为[M(Py)_m][TCNQ]_n(M=Mn,m＝4;M＝Co,Ni,Cu,m＝2;TCNQ＝7,7,8,8-四氰基对苯醌二甲烷,n＝2,3)的8个过渡金属吡啶配离子的TCNQ电荷转移盐,通过元素分析、红外光谱、顺磁共振谱、光电子能谱、磁化率和电导率对这些电荷转移盐进行了表征,结果表明,在这些电荷转移盐分子中存在TCNQ^-和TCNQ⁰,且TCNQ^-与TCNQ⁰相互作用形成结构单元[TCNQ]_n^2-(n＝2,3),各个结构单元沿一维方向堆积形成分子柱,部分电荷从[TCNQ]_n^2-向[M(Py)_m]²⁺转移,导致化合物中的金属表现为混合价态.其中3个电荷转移盐具有良好的导电性.     

Direct current conduction in ammonium perchlorate single crystals

The dc electrical conductivity of pure and doped ammonium perchlorate (AP) has been studied in two different crystal orientations, with the electric field applied perpendicularly to either (001) or (210) planes. The conductivity along the direction of the c axis was found to be lower than that normal to (210) by a factor of 5 to 10. The dc electrical conductivity of AP is decreased by Pb²⁺ ions but increased by SO^2?₄ and CrO^2?₄ ions. The conductivity of pure AP and of Pb²⁺-doped AP displays two regions with activation energies for conduction of 0.56 and 0.87 eV, respectively. The conductivity of the anion-doped crystals has a single activation energy, 0.66 eV for SO^2?₄ and 0.72 eV for CrO^2?₄. Exposure to ammonia enhances the conductivity of pure AP. A proton conduction mechanism is proposed that takes due regard of the structure of AP. The effect of the various additives on the conductivity are attributed to their influences on the formation of charge-carrying protons.     

Synthesis and structural characterization of a TCNQ based organic semi-conducting material with a 2:5 stoichiometry

The tetrabutylammonium complex with a 2:5 stoichiometry, (n-Bu(4)N)(2)(TCNQ)(5), has been prepared and structurally characterized by X-ray crystallography. Diagnostic bands in the Raman spectrum and signature features in the electrochemistry confirm that the TCNQ moieties are partially charged in the solid state. EPR, magnetic susceptibility, and electrical conductivity measurements are all consistent with (n-Bu(4)N)(2)(TCNQ)(5) behaving as a quasi-one-dimensional organic semiconductor.     

MTDTPY.TCNQ及MTDTPY.CHL电荷转移复合物晶体的电子能带结构 及其与导电性能 关系的研究

用紧束缚近似的EHMO方法对αMTDTPY.TCNQ(1)、β-MTDTPY.TCNQ(2)及MTDTPY.CHL(3)三种电荷转移复合物晶体的电子能带进行了计算。在1中,电子施体(D)分子MTDTPY及受体(A)分子TCNQ形成交替重叠的一维分子柱(M),柱间无净电荷转移。能隙E~G=0.15eV,载流子的产生主要来自热激发。在2及3中,电子施体(D)MTDTPY及受体(A)TCNQ及CHL分子分别相对独立的D及A一维分子柱,载流子的产生主要来自柱间的电荷转移。由电子能带结构及关于载流子迁移的Frohlich-Sewell公式,得出上述三种晶体的室温电导率之比为σ1:σ2:σ3=3.75×10^-^1^0:1:1.15,与实验事实基本一致。关于各分子柱对σ的贡献,2中D柱:A柱～10^3:1;3中D柱:A柱～2:1。根据计算结果,本文还对载流子的迁移机理进行了讨论。     

DC Electrical Conductivity of Polymercaptobenzothiazole Disulfide Copper Complex

Polymercaptobenzothiazole disulfide-copper complex PMBTS-Cu has been synthesized by reacting 2-mercaptobenzothiazole disulfide with CuCl₂ in absolute ethanol and dimethyl sulfoxide (DMSO) under reflux for 24 h. PMBTS-Cu has been characterized by several techniques using electronic spectra, elemental analyses, FTIR spectroscopy, and its solubility has been investigated. DC electrical conductivity variation with temperature, in the range 300–500 K, after annealing for 24 h at 100°C, and doping with different ratios of I₂, is determined for comparison. Doping was done in two ways: by mixing and chemically. Activation energies were calculated and the results were interpreted using the band energy model. DC electrical conductivity of I₂doped PMBTS-Cu complex increased with increasing temperature due to the variation of the carrier concentration with temperature as in the case of semiconductors. PMBTS-Cu complex has a copper ion in its backbone and copper salt is known to be a good dopant. Thus, these materials are doped internally, so the doped polymer-Cu complex are only one or two orders of magnitude higher in DC electrical conductivity than the annealed state. However, the energy gap is very small, which suggests suitability in applications like photovoltaic cells.     

(Aza)dithiafulvalenes as π-electron donors

(Aza)1,2- and 1,4-dithiafulvalenes are more difficult to oxidize than tetrathiafulvalenes. Depending on substituents, (aza)dithiafulvalenes react with tetracyano-p-quinodimethane (TCNQ) either in a 1:1 or 2:3 ratio to form heterofulvalenium 7,7,8,8-tetracyano-p-quinodimethanides. The electrical conductivity of these salts strongly depends on substituents. The conductivities of alkylthiofulvalene-TCNQ salts are much higher than those of phenyl-substituted derivatives.     

聚乙烯基咔唑／聚硝基苯掺杂体系的性能研究

研究了ＰＶＫ／ＰＮＢ掺杂中两种聚合物的相互作用，发现ＰＮＢ比ＴＮＦ能更有效地与ＰＶＫ形成电荷转移复合物，从而在很大程度上改变了ＰＶＫ原来的电学性质。随着掺杂浓度的增大，该体系逐渐从半导体特性向导体方向转变。     

Energy level tuning of polythiophene derivative by click chemistry‐type postfunctionalization of side‐chain alkynes

A polythiophene derivative substituted with electron‐rich alkynes as a side chain was synthesized using the Suzuki polycondensation reaction. The electron‐rich alkynes underwent the “click chemistry”‐type quantitative addition reaction with strong acceptor molecules, such as tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ), resulting in the formation of donor–acceptor chromophores. All polymers showed excellent solubilities in the common organic solvents as well as good thermal stabilities with their 5% decomposition temperatures exceeding 230 °C. The TCNE‐/TCNQ‐adducted polymers displayed well‐defined charge‐transfer (CT) bands in the low energy region. The CT energy of the TCNE‐adducted polymer was 2.56 eV (484 nm), which was much greater than that of the TCNQ‐adducted polymer [1.65 eV (750 nm)]. This result was supported by the electrochemical measurements. The electrochemical band gaps of the TCNE‐adducted polymers were much greater than those of the corresponding TCNQ‐adducted polymers. Furthermore, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, determined from the first oxidation and first reduction peak potentials, respectively, decreased with the increasing acceptor addition amount. All these results suggested that the energy levels of the polythiophene derivative can be tuned by varying the species and amount of the acceptor molecules using this postfunctionalization method. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Electric conductivity of TCNQ salts of ionene polymers containing triethylenediammonium or 4,4′-bipyridilium ring

The ionene polymers were prepared by the Menshutkin reaction of α,ω-dibromoalkane (n) with triethylenediamine (TDA) or 4,4′-bipyridil (BP). Resistivities (p) and activation energies of conduction (E_a) were measured for the polymeric 7,7,8,8-tetracyanoquinodimethan (TCNQ) salts with these ionenes. The correlation between the chemical structure of the ionenes and the conductivity was discussed. In the TDA,n-TCNQ complex salts and the BP,n-TCNQ simple salts the salts of the ionenes containing even numbers of CH₂ groups showed higher conductivities than those of the ionenes containing odd numbers of CH₂ groups. The conductivities determined by the narrower interval between the N⁺ cations of the main chains were measured in the simple salts. In the complex salts the conductivities determined by the larger interval were measured. The conformational change of the matrix ionenes affected the arrangement of the TCNQ molecules. The values of p were 79.7 and 12.5 Ω cm, and the values of E_a were 0.122 and 0.063 eV for TDA,4-TCNQ complex salt and BP,5-TCNQ complex salt, respectively.     

Simultaneous Spin-Crossover Transition and Conductivity Switching in a Dinuclear Iron(II) Coordination Compound Based on 7,7′,8,8′-Tetracyano-p-quinodimethane

The reaction of Fe(OAc)₂ and Hbpypz with neutral TCNQ results in the formation of [Fe₂(bpypz)₂(TCNQ)₂](TCNQ)₂ ( 1 ), in which Hbpypz=3,5-bis(2-pyridyl)pyrazole and TCNQ=7,7′,8,8′-tetracyano-p-quinodimethane. Crystal packing of 1 with uncoordinated TCNQ and π–π stacking of bpypz⁻ ligands produces an extended two-dimensional supramolecular coordination assembly. Temperature dependence of the dc magnetic susceptibility and heat capacity measurements indicate that 1 undergoes an abrupt spin crossover (SCO) with thermal spin transition temperatures of 339 and 337 K for the heating and cooling modes, respectively, resulting in a thermal hysteresis of 2 K. Remarkably, the temperature dependence of dc electrical transport exhibits a transition that coincides with thermal SCO, demonstrating the thermally induced magnetic and electrical bistability of 1 , strongly correlating magnetism with electrical conductivity. This outstanding feature leads to thermally induced simultaneous switching of magnetism and electrical conductivity and a magnetoresistance effect.     

Preparation, photo- and electro-luminescent properties of a novel complex of Tb (III) with a tripod ligand

A novel Tb(III) complex TbL (L=tris[2-(2-carboxyphenoxy)ethyl]amine, H3L) was synthesized and characterized by means of elemental analyses, IR spectra, thermal analyses, and molar conductivity measurement. The photoluminescent properties of the complex were investigated. In addition, PVK doping Tb(III) complex was fabricated as the emissive layer by spin-coating and its electroluminescent properties were studied, in which the structure of the device was ITO (indium tin oxide)/PVK (polyvinylcarbazole)/PVK: TbL/PBD (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole)/LiF/Al. It was indicated that pure green and narrow bandwidth emission at 545nm from photoluminescence of TbL complex film and the organic electroluminescent device is the characteristic emission of Tb(III) ion, and the electroluminescence spectrum of the device was very similar to that of the photoluminescence of TbL complex film. The lowest triplet level of the ligand was calculated from the phosphorescence spectrum of GdL in N,N-dimethyl formamide (DMF) dilute solution determined at 77K, and the energy transfer mechanisms in TbL complex were discussed.     

Alternating π‐conjugated copolymer of dithiafulvene with 2,2′‐bipyridyl units

A π‐conjugated polymer containing a dithiafulvene unit and a bipyridyl unit was prepared by cycloaddition polymerization of aldothioketene derived from 5,5′‐diethynyl‐2,2′‐bipyridine. Ultraviolet–visible (UV–vis) absorption spectra showed that the π‐conjugation system of the polymer expanded more effectively than that of a benzene analogue of poly(dithiafulvene) obtained from 1,4‐diethynylbenzene. Cyclic voltammetry measurements indicated that the dithiafulvene–bipyridyl polymer was a weaker electron‐donor polymer than the benzene analogue. These results supported the idea that the incorporation of the electron‐accepting bipyridyl moiety into conjugated poly(dithiafulvene) induced an intramolecular charge‐transfer (CT) effect between the units. Treatment of the dithiafulvene–bipyridyl polymer with bis(2,2′‐bipyridyl)dichlororuthenium (II) [Ru(bpy)₂Cl₂] afforded a ruthenium–polymer complex. A cyclic voltammogram of the complex showed broad redox peaks, which indicated electronic interaction between the dithiafulvene and tris(bipyridyl) ruthenium complex. The dithiafulvene–bipyridyl polymer formed CT complexes with 7,7,8,8‐tetracycanoquinodimethane (TCNQ) in dimethyl sulfoxide. The UV–vis absorption indicated that the resulting CT complex contained anion radical of TCNQ and partially charge‐transferred TCNQ. The polymer showed an unusually high electrical conductivity of 3.1 × 10^?4 S/cm in its nondoped state due to the effective donor–acceptor interaction between the bipyridine unit and the dithiafulvene unit. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4083–4090, 2001     

Anisotropic electrical conductivity of drawn elastomeric ionene–TCNQ salts

Elastomeric ionene–TCNQ salts with favorable electrical, mechanical, and processing characteristics were drawn mechanically. The electrical conductivity parallel and perpendicular to the drawing axis was investigated. Correlation between anisotropic conductivity and the change in microstructure was discussed. The resistivity ρ at 25°C of the simple salt (EI-TCNQ₀) and the complex salt (EI-TCNQ_0.5) were on the order of 10⁵ and 10² Ω cm, respectively. In the drawn TCNQ salts, the ρ parallel to the drawing axis increased greatly; on the other hand, the ρ perpendicular to this axis increased slightly or was similar to the ρ of the undrawn TCNQ salts. The anisotropy in the ρ of EI-TCNQ_0.5 between the two directions reached 40 times. The activation energy also increased in the direction parallel to the drawing axis. In the undrawn TCNQ salts, the continuous conduction paths exist isotropically. With drawing, the continuous conduction paths, particularly in the direction parallel to the drawing axis, break or make a structural change. The anisotropic conductivity disappeared with time in EI-TCNQ₀; however, it was present in EI-TCNQ_0.5 even after 200 days under ambient conditions.     

Tetracyanoquinodimethane Reduction by Complexed Guanidinyl‐Functionalized Aromatic Compounds

In this work, we report on the reduction of tetracyanoquinodimethane (TCNQ) with dicationic complexes of guanidinyl‐functionalized aromatic (GFA) electron donors. In contrast to reduction with free GFAs, milder reduction conditions were achieved, and this led to semiconducting materials with extended TCNQ π stacking. The charge on the TCNQ units was estimated from the structural data obtained by single‐crystal X‐ray diffraction analysis and from IR spectroscopic data. The electrical conductivity was studied and the activation energy of the semiconducting materials was estimated from the temperature dependence of the conductivity.     

CONDUCTING BLENDS OF POLY (2-VINYL PYRIDINE) AND POLYETHYLENE OXIDE WITH HIGH MOLECULAR WEIGHT

Ionic, electronic and mixed (ionic-electronic) conductivities of blends of poly(2-vinylpyridine) (P2VP) and poly(ethylene oxide) (PEO) with high molecular weight after dopedwith LiClO_4, TCNQ or LiClO_4 and TCNQ were investigated. Effects of LiClO_4 and TCNQconcentrations on the conductivity of PEO/P2VP/LiClO_4 or TCNQ blend were studied.The ionic conductivity of PEO/P2VP/LiClO_4 blend increases with increasing PEO content.At a Li/ethylene oxide molar ratio of 0.10 and a TCNQ/2-vinyl pyridine molar ratio of 0.5,the mixed conductivity of PEO / P2VP / LiClO_4 / TCNQ is higher than the total of ionicconductivity of PEO/P2VP/LiClO_4 and electronic conductivity of PEO/P2VP/TCNQwhen the weight ratio of PEO and P2VP is 6/4 or 5/5. Scanning electron microscopy(SEM) on the broken cross-section of the PEO/P2VP/LiClO_4 blend and differential scan-ning calorimetry (DSC) results show that LiClO_4 could act as a compatibilizer in the blend.     

一种军械油料快速检测方法研究

采用YX1154油料电导率测定仪研究了组分变化对45号变压器油和通用装备液压油两种油料电导率的影响,探索了电导率与传统测试指标的相关性.结果表明:油品电导率随防锈剂含量变化呈线性增加,并且与油料防锈性能测定结果一致.因此,该方法不仅可用于军用油料的生产质量检测和库存质量监控,而且可作为野战条件下评价油料性能的快速检测方法.     

LIGHT-INDUCED ELECTRICAL EFFECTS IN A LIQUID CRYSTAL BLM CONTAINING TCNQ

Abstract— The light-induced capacitance changes and also both photovoltage and photocurrent under continuous illumination have been investigated in pigmented liquid crystal bilayer membranes (PBLM)‡ containing TCNQ as photosensitizer with Na₂SO₃ electron donor on one side and methylene blue electron acceptor on the other side. The results have shown that TCNQ in cyanobiphenyl membrane produces a unique photoactive BLM system in which all three main parameters (conductivity, capacity and voltage across the membrane) are in a wide range altered by the light. It is shown that a TCNQ-cyanobiphenyl charge transfer complex is responsible for the observed photochanges. The possible mechanism of photoinduced electrical effects in this type of PBLM is discussed.     

Electroactivity, electrochemical stability and electrical conductivity of multilayered films containing poly(3,4-ethylendioxythiophene) and poly(N-methylpyrrole)

Multilayered systems of poly(3,4-ethylendioxythiophene) and poly(N-methylpyrrole) have been prepared using a layer-by-layer electrodeposition technique. The electrochemical and electrical properties of films formed by 3, 5, 7 and 9 layers have been characterized and compared with those of pure polymers and copolymers prepared from mixtures of 3,4-ethylendioxythiophene and N-methylpyrrole with various concentration ratios. Results indicate that the electroactivity and electrical stability of the multilayered systems are higher than those of both poly(3,4-ethylendioxythiophene) and copolymers. Furthermore, these electrochemical properties improve when the number of layers increases. On the other hand, the electrical conductivity of the multilayered systems is slightly lower than that of pure poly(3,4-ethylendioxythiophene), and significantly higher than those of poly(N-methylpyrrole) and copolymers.     

四硫代富瓦烯及其CT复合物导电LB膜

通过Langmuir-Blodgett（LB）技术制备导电性有机超薄膜近年来受到了广泛的关注，导电LB膜的膜材料主要是含有电子受体77’，8，8’一四氨基二亚甲基本自（TCN则的电行转移（CT）复合物间以及给体分子特别是四流代宫瓦烯衍生物［‘刮.在以前的工作中，我们曾报导了四等基硫四硫