Conjugated oligomers with thiophene and indole moieties: Synthesis,photoluminescence and electrochromic performances

Two series of thiophene oligomers and terthiophene oligomers consisting of both thiophene and indole moieties have been synthesized. They have same excitation-dependent photoluminescence characteristics, but different bandgaps and absorption behaviors, which relates to the number and denseness of indoles in the conjugated oligomers and the length of alkyl chains on indole moiety due to varied the π-π stacking interaction of conjugated structures in the as-prepared oligomers. A simple electrochromic device based on such a conjugated oligomer displays a novel four-color electrochromism from red to yellow, green and puce with the increased potential and possesses good environmental and redox stability. Such conjugated oligomer also exhibits high sensitivity and selectivity for Zn²⁺ detection.     

低分子量聚噻吩结晶结构研究

用Ruland方法计算了氯仿可溶级分低分子量聚噻吩(PT_1)热处理前后的结晶度。热处理后结晶度及微晶尺寸均有明显提高。测量及计算晶胞参数证明,PT_1在晶态下具有近似平面伸展构象,提出了初步的结构模型。热处理前后的PT_1给出了明确可归属的红外吸收谱带。     

导电聚合物单体的光电聚合

苯胺、吡咯和噻吩等是重要的导电聚合物单体.光照可促进低聚物的形成,电化学技术可方便地实现单体的电聚合.目前,有关导电聚合物单体的光电聚合的报导还很少.本文研究征水溶液中、铂金属基底上,苯胺、吡咯和噻吩等单体的光电聚合过程.     

New photosetting NLO-active polythiophenes with enhanced optical stability

A new molecular design strategy devoted to the obtainment of polythiophenes showing a second-order NLO response that is stable in time is reported and commented on. The adopted synthetic procedure, based on the functionalization of soluble and stable polymeric precursors, leads to a photocrosslinkable polymer which, after curing, shows a decay of the order parameter ? notably slower than in previously synthesized NLO-active polymers containing the same kind of chromophore. The curing conditions have been carefully monitored and optimized, since they not only influence the chain mobility, but also strongly affect the electronic delocalization of the polyconjugated backbone. Detrimental effects can, however, be avoided by using suitable functional groups in the side chains, acting as internal plasticizers without being sensitizers for the photobleaching process.     

Effect of a buffer layer, composition and annealing on the performance of a bulk heterojunction polythiophene/fullerene composite photovoltaic device

Post-annealing of P3HT/C₆₀-based plastic solar cells, composite ratio and, incorporation of a buffer layers at the ITO–polymer/fullerene composite interface and the polymer/fullerene composite–Al interface have shown significant improvement in the performance of the photovoltaic device, both in terms of open-circuit voltage and short-circuit current. The annealing temperature, time duration and P3HT/C₆₀ composite ratios have been optimized for the best performance of typical ITO/PEDOT:PSS/P3HT:C₆₀/LiF/Al solar cell. The C₆₀ content is very crucial because it improves the photocurrent in the beginning but after a certain value it leads to decrease in absorption, thereby decreasing the photocurrent.     

Fluorination strategy enables greatly improved performance for organic solar cells based on polythiophene derivatives

The power conversion efficiencies(PCEs) of organic solar cells(OSCs) have reached 18% recently,which have already met the demand of practical application.However,these outstanding results were generally achieved with donor-acceptor(D-A) type copolymer donors,which can hardly fulfill the low-cost largescale production due to their complicated synthesis processes.Therefore,developing polymer donors with simple chemical structures is urgent for realizing low-cost OSCs.Polythiophene(PT) derivatives are currently regarded as promising candidates for such kind of donor materials,which has been illustrated in many works.In this work,two new alkylthio substituted PT derivatives,P301 and P302,were synthesized and tested as donors in the OSCs using Y5 as the accepto r.In comparison,the introduction of fluorine atoms on the backbone of P302 can not only downshift the energy levels,but also greatly improve the phase separation morphologies of the active layers,which is ascribed to the enhanced aggregation effect and the reduced miscibility with the non-fullerene acceptor.As a result,the P302:Y5-based OSC exhibits a significantly improved PCE of 9.65% than that of P301:Y5-based one,indicating the important role of fluorination in the construction of efficient PT derivative donors.     

Pyrolysis Mass Spectrometry Analysis of BF4 − Doped Polythiophene

Abstract

Pyrolysis of electrochemically prepared BF₄ ^? doped polythiophene (PTh) by direct insertion probe and Currie point pyrolysis gas chromatography mass spectrometry techniques indicated that thermal decomposition of PTh occurs in two steps. In accordance with literature results, the first step is assigned to the loss of the dopant, and the second step to the degradation of the polymer backbone producing segments of various conjugation lengths. At elevated temperatures, detection of products such as H₂S and C₂H₂ indicating cleavage of the thiophene (Th) ring was associated with a network structure. For the dedoped samples, a significant increase in the relative intensities of the peaks characteristic to the counter ion of the dopant, N(C₄H₉)₄ ⁺ pointed out the inward diffusion of (C₄H₉)₄N⁺ during the dedoping process.     

Pine Needle-like Nanocomposite： Supercritical CO2 Assisted Polythiophene Synthesis on Carbon Nanotubes

A facile method was succcssfidly developed to prepare a ＂pine needle-like＂ nanocompositc of carbon nanotubcs/polylhiophenc（CNTs/PTh） in ethanol with the assistance of supercritical CO2（SC CO2）. The experiment conditions such as mass ratio of thiophene monomer to carbon nanotubes, reaction temperature, and reaction time wcrc optimized, and the morphology and thickness of PTh layers on CNTs were hence effectively controlled. The results of Fourier translbrm infrared（FTIR） spectra, X-ray photoelectron spectra（XPS） and Raman spectra indicate the π-π interactions between PTh and CNT. A possible formation mechanism about the unique microstructure was suggested by virtue of the morphological evolution of the nanocomposite. As a facile, environment benign, and adjustable method, the proposed method holds great potential in the preparation of functional hybrid nanocomposites with the help of SC CO2, which will be promising in the tields of nanofabrication and electrochemical device preparation.     

An electroactive polymeric material and its voltammetric response towards alkali metal cations in neat water

The syntheses and characterization of a unique system based on thiophene, pyrrole and benzo-15-crown-5 (SNS-Crown) and its corresponding polymer (PSNS-Crown) are reported. Furthermore, selective, clear and reversible voltammetric responses of the conjugated polymer (PSNS-Crown) film towards the alkali series Li⁺, Na⁺ and K⁺ in both neat water and organic media (ethanol) are described.     

An n-Type Polythiophene Derivative with Excellent Thermoelectric Performance

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.