Thieno[3,2-b]thiophene as π-bridge at different acceptor systems for electrochromic applications

Preparation and electrochemical properties of thieno-[3,4-b] pyrazine conjugated polymer composite supercapacitor carbon powder electrode materials for Li-organic battery

In this work, two D-A monomers 2,3-di(5-methylfuran-2-yl)-5,7-di(thiophene-2-yl) thiopheno[3,4-b] pyrazine (MFTTP) and 2,3-di(5-methylfuran-2-yl)-5,7-di(4-methoxythiophen-2-yl) thiopheno [3,4-b] pyrazine (MFMOTTP) were first obtained by Stille Coupling reaction, and then the corresponding composites were obtained by in-situ oxidative polymerization method with supercapacitor carbon. The surface morphology, chemical structure, and the element valence states of two materials were characterized by scanning electron microscopy, infrared and XPS, respectively. The specific surface areas of PMFTTP@SC and PMFMOTTP@SC are measured as 756.5 and 954.9 m2/g, respectively. The CV curves were used to determine the initial oxidative and initial reduction potentials, both polymers have a narrow band gap with Eg values below 1.5 eV, electron clouds in the HOMO and LUMO orbits of the polymer are mainly distributed on the aromatic rings of the polymer backbone. Polymer composite materials were used as the anode materials and the lithium sheets were used as counter electrode, and then lithium ion batteries are assembled. The first discharge specific capacities of PMFTTP@SC and PMFMOTTP@SC are 741.9 and 951.3 mAh/g at a current density of 100 mA/g, and as the electrodes are activated in the subsequent cycles, their coulomb efficiencies can reach more than 92% from the third cycle. In contrast, PMFMOTTP with methoxy-thiophene as the donor unit has higher conductivity and lower corresponding impedance due to its stronger electron donating ability and abundant pore structure, which is also more conducive to the lithiation/delithiation redox process.

Electrochemical and Solvent-Mediated Visible-to-Near-Infrared Spectroscopic Switching of Benzoselenadiazole Fluorophores

A series of electronic push-pull, pull-pull, and push fluorophores has been prepared from a benzoselenadiazole core so that their spectroscopic, electrochemical, spectro-electrochemical, and spectro-electrofluorescence properties could be examined. The emission wavelengths and fluorescence quantum yields (Φ_fl ) of the N,N-dimethyl fluorophores were contingent on the solvent polarity and they ranged from 615 to 850 nm in aprotic solvents. The positive solvatochromism and the quenched Φ_fl in polar solvents were consistent with an intramolecular charge-transfer state (ICT). Meanwhile, a locally excited state (LE) was assigned in nonpolar solvents from the blue-shifted emission and high Φ_fl . The N,N-dimethylamine fluorophores examined could be both electrochemically oxidized and reduced, whereas the symmetric dinitro pull-pull derivative could be only reversibly reduced. Courtesy of their electrochemical reversibility, the fluorophores could reversibly change color from yellow to blue with an applied potential in addition to switching off their emission. The absorption of the electrochemically generated intermediates of the N,N-dimethyl derivatives spanned 500 nm over the visible and the NIR regions. The colors could be switched for upwards of two hours with applied potential, illustrating their potential use as electroactive materials in electrochromic devices.

Effects of the acceptor pattern and substitution position on the properties of N-phenyl-carbazolyl based donor–acceptor–donor molecules

Four D–A–D type molecules were designed and synthesized, and their specific properties including optical, redox and thermal stabilities were studied in detail. The influence of substitution and the heteroatom effects were also studied.

Effects of different functional groups on the optical and charge transport properties of copolymers for polymer solar cells

Three novel copolymers were designed based on BSeTT, QTT, BDT-DTBTBPz and BDT-DTBTBQx. Their properties of ground state and excited state were calculated via DFT/TDDFT methods. The charge moves from polymers to PC₆₀BM.

Synthesis of donor–acceptor copolymer using benzoselenadiazole as acceptor for OTFT

The synthesized copolymer has a low band gap and exhibits a hole mobility of around 0.1 cm² V⁻¹ s⁻¹.

Synthesis and electrochromic, acidochromic properties of Schiff bases containing triphenylamine and thiophene units

A series of Schiff bases (SBs) were designed and prepared from 2-thiophenecarboxaldehyde and different triphenylamine (TPA) derivatives. The structures of the compounds were characterized by Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance (1H NMR). The optical and electrochemical properties were tested by ultraviolet-visible (UV-vis) spectroscopy and cyclic voltammetry (CV) techniques. The SBs exhibited stable and reversible electrochromic properties. Furthermore, multiple reversible colors states were also observed with the change of pH. Consequently, the SBs can be used as electrochromic and acidochromic materials.