苯并[1,2-b:4,5-b']二噻吩的共轭聚合物光伏材料的能隙的理论研究

共轭聚合物材料的吸收谱带和能隙是影响太阳能电池(PSCs)能景转换效率(PCE)的主要因素,为了预测吸收谱带和能隙提高新型共轭聚合物的光伏性能,用量子化学方法计算了具有不同共轭单体的苯并[1,2-b:4,5-b']二噻吩(BDT)的吸收光谱和能隙.基态分子结构优化用密度泛函理论(DFT)B3LYP方法及6-31G(d)基组,吸收光谱和最低激发能(Eg)用含时密度泛函理论(TD-DFT)计算.聚合物的△H-L和Eg值用外推法计算,而且提出了相关参数用以调控共轭聚合物能隙和吸收谱带.计算结果与实验结果相符.     

Organic‐inorganic heterojunction electroluminescent device fabricated by conjugated polymer and zinc oxide*

Abstract— In this study an organic‐inorganic heterostructure device was fabricated. This hybird device consisted of two layers, one of which was a conjugated polymer layer and the other an inorganic material layer. Compared with a single conjugated polymer layer device of the same thickness, the emission intensity increases about 5–8 times. The inorganic layer plays the role of the electron‐transport layer similar to its organic heterojunction counterpart.     

基于荧光共轭聚电解质的小檗碱检测

利用含磺酸基侧链的聚苯乙炔类共轭聚电解质PPESO3作为荧光探针检测小檗碱,由于磺酸基阴离子侧链与小檗碱的季铵阳离子之间的静电相互作用形成了复合物,导致了PPESO3荧光信号显著地猝灭。在优化条件下,采用该方法检测小檗碱的线性范围为7.5×10-8mol/L～4.0×10-6mol/L,检出限为8.7×10-9mol/L(S/N=3)。     

Nitroaromatic compounds sensing. Synthesis,photophysical characterization and fluorescence quenching of a new amorphous segmented conjugated polymer with diphenylfluorene chromophores

A new regularly segmented conjugated polymer bearing 2,7-diphenylfluorene chromophores tethered by isopropylidene connectors was synthesized by a relatively short synthetic route starting from easily available monomer synthons. Its photophysical properties were investigated using UV–vis absorption, steady state and time-resolved emission spectroscopies. The bent microstructure produces a highly soluble amorphous polymer and fluorescence depolarization showed that exciton mobility within the polymer film is not hindered. These properties are of practical significance in view of the high sensitivity and fast response of its fluorescence quenching by nitro aromatics. Half of the maximum quench (Q_50%) of a polymer film occurred with dinitrobenzene in methanol solution at the micromolar range in less than 1 min in a reversible manner. We demonstrate that amorphous segmented conjugated polymers bearing relatively short chromophores can be used as sensing materials with performances comparable to those presented by conjugated polymers with more elaborate structural design.     

共轭导电聚合物及其在传感器中的应用

分析了共轭导电聚合物的结构特征和导电机理，综述了共轭导电聚合物在离子传感器、气体传感器、湿度传感器和生物传感器中的应用和原理，并展望了共轭导电聚合物在传感器中的研究方向和应用前景。     

Small molecules with pyridine backbone modified with carbazole,fluorine and bromine for white light-emitting diode applications

Seven compounds with pyridine as the backbone modified by carbazole moiety, bromine atom and fluorine atom were synthesized. Compounds 1, 2, 3 with bromo substitution at the 2-position and carbazole modification at the 5-position of pyridine emit not only a sharp blue singlet fluorescence but also a wide banded excimer-based orange emission. The two colors coming from a single molecule can be used to fabricate a simplified white light emitting device. The electroluminescence based on 1 and 2 exhibits white-light emission with CIE coordinates of x = 0.25 and y = 0.30 for 1 and x = 0.33 and y = 0.37 for 2 at high current densities, very close to pure white emission. In addition, the role of bromo-substitution at pyridine is concluded to be essential to generate molecular interaction thus an excimer emission.     

Enhancement of photochromic hologram thermal stability

Significant enhancement of the thermal stability of the hologram recorded on photochromic materials had been achieved via covalent bonding of the photochromic dye to the polymer matrix as compared to the host-guest systems. One time partial reduction of the hologram’s initial diffraction efficiency due to thermal exposure was observed for both—polymers with attached dye as well as hostguest materials. Such one time reduction is interpreted to be due to the thermal relaxation of the polymer network induced with photochromic transition in the dye molecule. A gradual hologram erasure at elevated temperatures was observed for the host-guest system, which is assumed to be due to dye’s diffusion between highly lit and dark areas. For the photochromic materials with covalent boding of the dye to the polymer matrix the level of thermal stability is demonstrated such that at temperatures ca. 100C there was no detectable diffusion type degradation of the hologram after 6 hours of exposure to elevated temperature. Same heating of the hologram in photochromic host-guest polymer led to a full hologram erasure within 40 minutes. In both cases the one time initial DE reduction due to polymer matrix relaxation at elevated temperatures had comparable value of about 0.5 of hologram’s initial DE. The article is published in the original.     

Fibre-optic evanescent sensing of gaseous ammonia with two forms of a new near-infrared dye in comparison to phenol red

We report the evanescent detection of gaseous ammonia using the methylated and ethylated forms of a new dye and comparing their performance to that of the indicator dye phenol red. The two forms of the new dye were developed to produce spectral changes in the near-infrared region of the spectrum. Each of the dyes have been immobilised into the cladding material of commercial available plastic-clad silica (PCS) fibre. The response to gaseous ammonia was maximum at 565 nm for phenol red and 735 and 744 nm for the methylated and ethylated forms of the copper complex, respectively, and the calibration curves for the three dyes investigated exhibit a dynamic range of three orders of magnitude. Although all sensing fibres showed reversible responses to ammonia, the responses times were slow and need improving. The effect of atmospheric moisture on the copper complex methylated form was found to be negligible in the range of 0–50%RH.     

Uplink resource allocation in OFDMA system using distributed antennas

A plasmonic polymer composed of dumbbell resonator （DBR） molecules was synthesized. The DBRs were connected with each other through slits that act as chemical bonds, resulting in a strong exchange current interaction between these DBRs. The polymer structure has side atoms connected to the backbone. A TM wave can be coupled into these side atoms, and a coherent plasmon wave can be excited along the polymer chain. This introduces a resonance peak in the optical transmission spectrum. The dispersion property of such a coherent mode agrees well with the theoretical calculation results.     

Ionic liquid as electrolyte in a self-powered controlled release system

Initial studies into the development of a self-powered controlled release system using ionic liquid electrolyte were performed via galvanic coupling of a conducting polymer doped with dye and a zinc anode. The conducting polymer employed was polypyrrole (PPy) doped with phenol red (PR) dye. The electrochemical properties of the polymer as well as the dye release process initiated by a Zn electrode were investigated. A bilayer conducting polymer structure wherein polypyrrole–polystyrene sulfonate (PPy-PSS) coated on top of PPy-PR ensured no leakage of dye, yet allowed efficient release of PR on galvanic coupling in a temperature sensitive electrolyte.     

Selective heat-transfer dye diffusion technique using laser irradiation for polymer electroluminescent devices

The heat-transfer process described in this paper will be useful for controllably and selectively doping polymer films used to make hyperfine full-color polymer electroluminescent (EL) displays. A polymer receiver film is placed in direct contact with a dye-dispersed polymer film coated onto an efficient photo-absorbing substrate to permit heat-transfer dye diffusion. The widely used heat-mode magneto-optical storage material, TbFeCo was used as the photo-absorbing material. We irradiated it with a laser in order to generate heat. This method can be used to control the lateral and vertical dopant distributions in polymer films for EL devices. We demonstrated that coumarin 6 and Nile red can be doped into the rather thermally stable polymer poly(N-vinylcarbazole) containing the electron-transporting 2-(4-biphenylyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole from a viewpoint of luminescent properties. The diffusion power and time for about 1-mm² doping area were 1.2 W and about 10 s.     

利用掺杂制备高亮度的黄光器件

本文采用一种高荧光效率的黄光荧光染料rubrene作为掺杂剂掺杂在母体材料Alq3和NPB中,由于rubrene分子具有俘获空穴和传输电子的能力,Rubrene成了主发光体,Alq和NPB变成了客发光体,出现了发光体的互换现象,控制激子在某一层面上有效的复合。在相同掺杂浓度下,得到了高亮度的有机电致发光器件,器件的色坐标也是比较稳定的,均为稳定的黄光发射。该器件的最大亮度在13v时,为18250cd/m2,通过一系列的实验可以说明,在发光层中,掺杂客体荧光染料能极大地提高OLED的性能和特性。     

New conjugated polyenes with 1,3-dialkyl-2-thiobarbituric acid moiety as materials for nonlinear optics: theoretical calculations, synthesis and spectral properties

In this work we report the results of our study on electronic and spectral properties of conjugated polyenes with electron-accepting 1,3-dialkyl-2-thiobarbituric acid moiety. In model calculations, we examine the effect of the conjugated polyene length on infrared (IR) and Raman spectra of the polyenes by means of ab initio HF/3-21G*. Nonlinear properties were also studied by AM1 method in frames of the sum-over-states (SOS) and finite-field formalism. It was concluded that in well-resolved IR and Raman spectra the frequencies and band intensities can provide valuable information relating to C=C bond lengths in polyene chain and relative polarizabilities. Near-linear correlation between polarizability and integral IR band intensity, corresponding to all C=C stretching modes, and the rather nonlinear relationship of polarizability with integral Raman activity, was found. In our calculation we predict that polarizability and the first hyperpolarizability increases with elongation of polyene chain while the second hyperpolarizability increases smoothly in a quadratic way. In contrast to the linear relationship between polarizability and polyene chain length the dipole moment versus chain length is predicted to be nonlinear. A good agreement was found between experimental and calculated Raman spectra of one newly synthesized compound studied.     

Parallel algorithm for calculation of the exact partition function of a lattice polymer

We develop a parallel algorithm that calculates the exact partition function of a lattice polymer, by enumerating the number of conformations for each energy level. An efficient parallelization of the calculation is achieved by classifying the conformations according to the shape of the box spanned by a conformation, and enumerating only those in a given box at a time. The calculation time for each box is reduced by preventing the conformations related by symmetries from being generated more than once. The algorithm is applied to study the collapse transition of a lattice homopolymer on a square lattice, by calculating the specific heat for chain lengths up to 36.     

Aggregate‐induced emission in light‐emitting liquid crystal display technology

Nowadays, liquid crystal displays (LCDs) with light‐emission are considered as energy‐efficient devices and are promising alternatives to conventional LCDs. To realize such possibility, strong fluorescent materials with a dichroic properties are required. Aggregate‐induced emission (AIE) is an unusual photophysical phenomenon shown by some luminogenic materials that will be highly emissive in their aggregate state. In this work, we studied the AIE effect of a luminescent liquid crystalline molecule TPE‐PPE in our LC system as a luminophore dopant. The result showed the excellent AIE effect that higher concentration of luminogen in the nematic LC host induced stronger luminescent intensity. Through exposure of a photoisomeriable alignment material sulfonic‐dye‐1, the photopatterning of a light‐emitting LC device was achieved with the use of the TPE‐PPE/nematic LC mixture.     

Materials optimization for semiconducting polymer LEDs and FETs

Dye‐doped semiconducting polymers are used as active layers in polymer light‐emitting diodes (polyLEDs). The emission color can be tuned by doping the active polymer with certain dyes. This concept of energy transfer is demonstrated for a green matrix doped with a red‐emitting dye, suitable for use in LEDs. An absolute PL efficiency of 39% is observed for this system. Another very attractive development is taking place in the area of all‐polymer transistors. This may lead to a (partial) replacement of the driving electronics by all‐plastic circuits. A new precursor route toward poly(thienylenevinylene)s (PTVs), suitable as active material in all‐polymer integrated circuits, is presented. Synthesis of the precursors is reproducible and fast, and can readily be scaled for manufacture. Quantitative conversion of the precursor polymer can be accomplished by heating at 150°C for 20 min. The resulting mobility (6 × 10^?3 cm²/V‐sec) and ON‐OFF ratio (4 × 10⁴) makes this material a suitable candidate for the development and large‐scale manufacturing of all‐polymer integrated circuits.     

Patterned liquid‐crystal laser film for multi‐dimensional multi‐color emissive film technology

Abstract— A two‐dimensional array consisting of dye‐doped reflection‐mode holographic‐polymer‐dispersed liquid crystal (H‐PDLC) lasers with alternating pitch lengths is presented. These post structures each reflect at a narrow bandwidth of light. The addition of laser dye to the H‐PDLC system allows for the generation of laser emission at the edge of the reflection band, or photonic band gap. In patterning these H‐PDLC post structures, a narrow‐linewidth patterned emissive color film is realized. The potential of such films and their implication in the display industry is discussed. In creating a three‐color array, an active emissive color film could replace the backlight and color filter components within the display. Such a patterned system would possess a wide color gamut, through spatial color synthesis, formed by narrow‐linewidth lasing structures with well‐defined wavelengths of emission.     

A general purpose Fortran 90 electronic structure program for conjugated systems using Pariser-Parr-Pople model

Pariser-Parr-Pople (P-P-P) model Hamiltonian has been used extensively over the years to perform calculations of electronic structure and optical properties of π-conjugated systems successfully. In spite of tremendous successes of ab initio theory of electronic structure of large systems, the P-P-P model continues to be a popular one because of a recent resurgence in interest in the physics of π-conjugated polymers, fullerenes and other carbon-based materials. In this paper, we describe a Fortran 90 computer program developed by us, which uses P-P-P model Hamiltonian to not only solve Hartree-Fock (HF) equation for closed- and open-shell systems, but also for performing correlation calculations at the level of single configuration interactions (SCI) for molecular systems. Moreover, the code is capable of computing linear optical absorption spectrum at various levels, such as, tight-binding (TB) Hückel model, HF, SCI, and also of calculating the band structure using the Hückel model. The code also allows the user to solve the HF equation in the presence of finite external electric field, thus, permitting calculations of quantities such as static polarizabilities and electro-absorption spectra. Additionally, it can perform transformation of P-P-P model Hamiltonian from the atomic orbital (AO) representation (also called site representation) to the molecular orbital (MO) one, so that the transformed matrix elements can be used for high level post-HF calculations, such as, full CI (FCI), quadruple CI (QCI), and multi-reference singles-doubles CI (MRSDCI). We demonstrate the capabilities of our code by performing calculations of various properties on conjugated systems such as trans-polyacetylene (t-PA), poly-para-phenylene (PPP), poly-para-phenylene-vinylene (PPV), oligo-acenes, and graphene nanodisks.

Program summary

Program title: ppp.xCatalogue identifier: AEFW_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFW_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 79 900No. of bytes in distributed program, including test data, etc.: 508 285Distribution format: tar.gzProgramming language: Fortran 90. Compilers used: Program has been tested with Intel Fortran Compiler (noncommercial version 11.1) and gfortran compiler (gcc version 4.4.0) with optimization option -OComputer: PCs, workstationsOperating system: Linux. Code was developed and tested on various recent versions of Fedora including Fedora 11 (kernel version 2.6.29.4-167)Classification: 7.3, 16.1External routines: This program needs to link with LAPACK/BLAS libraries compiled with the same compiler as the program. For the Intel Fortran Compiler we used the ACML library version 4.3.0, while for gfortran compiler we used the libraries supplied with the Fedora distribution.Nature of problem: The problem of interest at hand is the electronic structure of π-conjugated systems. For such systems, the effective π-electron P-P-P semi-empirical model Hamiltonian proposed by Pariser, Parr, and Pople offers an attractive alternative as compared to the ab initio approaches. The present program can solve the HF equations for both open- and closed-shell systems within the P-P-P model. Moreover, it can also include electron correlation effects at the singles CI level. Along with the wave functions and energies, various properties such as linear absorption spectra can also be computed.Solution method: The single-particle HF orbitals of a π-conjugated system are expressed as linear combinations of the pz-orbitals of individual atoms (assuming that the system is in the xy-plane). Then using the hopping and Coulomb parameters prescribed for the P-P-P method, the HF integro-differential equations are transformed into a matrix eigenvalue problem. Thereby, its solutions are obtained in a self-consistent manner, using the iterative diagonalizing technique. The HF orbitals thus obtained can be used to perform a variety of calculations such as the SCI, linear optical absorption spectrum, polarizability, electro-absorption spectrum, etc.Running time: The examples provided each only take a few seconds to run. For a large molecule or a polymer, however, the run time may be a few minutes.     

Irreversible sensing of oxygen ingress

Absorption-based opto-chemical sensors for oxygen are presented that consist of leuco dyes (leuco indigo and leuco thioindigo) incorporated into two kinds of polymer matrices. An irreversible and visible color change (to red or blue) is caused by a chromogenic chemistry involving the oxidation of the (virtually colorless) leuco dyes by molecular oxygen. The moderately gas permeable copolymer poly(styrene-co-acrylonitrile) and a highly oxygen-permeable polyurethane hydrogel, respectively, are used in order to increase the effective dynamic range for visualizing and detecting oxygen. We describe the preparation and properties of four different types of such oxygen sensors that are obtained by dip-coating a gas impermeable foil made from poly(ethylene terephthalate) with a sensor layer composed of leuco dye and polymer.     

Color‐by‐Blue: A novel method to achieve full‐color inorganic EL displays

Abstract— A new method for achieving full‐color capability for inorganic EL displays was developed, which combines electroluminescence with photoluminescence phenomena in the same device structure. In this display panel, the blue emission was obtained from the EL device by using the Eu‐doped barium thioaluminate phosphor material system, which was then used to generate green and red emission by the use of down‐conversion materials. The major advantages of the Color‐by‐Blue method (CBB) are the elimination of color‐balance control issues associated with the use of different electroluminescent phosphor materials for red, green, and blue with potentially different threshold voltages for the onset of luminance and the achievement of a low‐cost high‐yield manufacturing process.