Synthesis and Electrochemical Properties of Oligo- and Poly(thienylphenylamine)s

Self-assembly of pendant functional groups grafted PEDOT as paracetamol detection material

In this paper, pendant functional group grafted EDOTs, such as EDOTCH₂NH₂, EDOTCH₂OH and EDOTCH₂SH, were selected as monomers for the preparation of their respective polymers via a common chemical oxidative polymerization method in the absence of CTAB by varying the [monomer]/[oxidant] ratios. The self-assembly mechanism of the polymers was systematically studied by discussing the hydrogen bonding effect, acidity and electron-donating ability, as well as the chain initiation and chain growth of the chemically oxidated polymerized monomers. These functional group grafted PEDOTs were applied to the electrochemical determination of paracetamol (PAR) to further investigate the effect of the pendant functional groups (-SH, -OH, -NH₂) on the electrochemical sensing behaviour of the polymers. The results indicated that the hydrogen bonding effect of the pendant functional groups was vital to the self-assembly of the polymer chains, and the PEDOTs with -OH and -SH groups had a tendency to self-assemble into a spherical structure, while the PEDOT with an -NH₂ group exhibited a fibrous structure. The electrochemical response of PEDOTs with functional groups was better than that that of PEDOT alone, and the highest electrochemical response was observed in PEDOT with an -SH group ([monomer]/[oxidant] = 1 : 8).

Redox-State Dependent Spectroscopic Properties of Porous Organic Polymers Containing Furan, Thiophene, and Selenophene

A series of electroactive triarylamine porous organic polymers (POPs) with furan, thiophene, and selenophene (POP-O, POP-S, and POP-Se) linkers have been synthesised and their electronic and spectroscopic properties investigated as a function of redox state. Solid state NMR provided insight into the structural features of the POPs, while in situ solid state Vis-NIR and electron paramagnetic resonance spectroelectrochemistry showed that the distinct redox states in POP-S could be reversibly accessed. The development of redox-active porous organic polymers with heterocyclic linkers affords their potential application as stimuli responsive materials in gas storage, catalysis, and as electrochromic materials.

Characterization and polymerization of thienylphenyl and selenylphenyl amines and their interaction with CdSe quantum dots

Hybrid quantum-dot-sensitized solar cells show promising novel optoelectronic properties. An adequate design of such cells requires a deep understanding of the characteristics of each component, including their interactions. In this context, the electrochemical properties of two different hole-transporting materials (HTMs) and their chemical interactions with trioctylphosphine-capped CdSe quantum dots are investigated to evaluate their potential use in hybrid quantum-dot-sensitized solar cells. Tris[4-(thien-2-yl)phenyl]amine (TTPA) and tris[4-(selen-2-yl)phenyl]amine (TSePA) are studied in the solid state as thin films deposited on a conducting substrate. Spectroelectrochemical studies evidence both solid-state electropolymerization and doping. Upon addition of TSePA or partially polymerized TTPA to a colloidal solution of trioctylphosphine-capped CdSe quantum dots, the steady-state photoluminescence is quenched. This suggests that the quantum dots and the HTM strongly interact, probably through an excited-state charge-transfer mechanism. The combination of all these pieces of information indicates that polymerized TTPA and TSePA are potential candidates as HTMs for hybrid quantum-dot-sensitized solar cells.

Self-assembled monolayers of metal-assembling dendron thiolate formed from dendrimers with a disulfide core

Novel phenylazomethine dendrimers with a disulfide core (SS-DPA G1-4) were synthesized in nearly quantitative yields. Although the disulfide core is shielded by the rigid dendron shell, direct formation of the self-assembled monolayers of metal-assembling dendron thiolate was observed by XPS and electrochemical reduction of the self-assembled monolayer substrates. The dendrimers showed a similar metal-assembling manner with other derivatives. The metal assembly to the self-assembled monolayers of metal-assembling dendron thiolate was also confirmed.

Triphenylamine-thienylenevinylene hybrid systems with internal charge transfer as donor materials for heterojunction solar cells

Star-shaped molecules based on a triphenylamine core derivatized with various combinations of thienylenevinylene conjugated branches and electron-withdrawing indanedione or dicyanovinyl groups have been synthesized. UV-vis absorption and fluorescence emission data show that the introduction of the electron-acceptor groups induces an intramolecular charge transfer that results in a shift of the absorption onset toward longer wavelengths and a quenching of photoluminescence. Cyclic voltammetry shows that all compounds present a reversible first oxidation process whose potential increases with the number of electron-withdrawing groups in the structure. Prototype bulk and bilayer heterojunction solar cells have been realized using fullerene C60 derivatives as acceptor material. The results obtained with both kinds of devices show that the introduction of electron-acceptor groups in the donor structure induces an extension of the photoresponse in the visible spectral region, an increase of the maximum external quantum efficiency, and an increase of the open-circuit voltage under white light illumination. These synergistic effects allow reaching power conversion efficiencies of approximately 1.20% under simulated AM 1.5 solar irradiation at 100 mW cm(-2).

A star-shaped triphenylamine π-conjugated system with internal charge-transfer as donor material for hetero-junction solar cells

Introduction of dicyanovinyl groups on a triphenylamine-based conjugated system leads to an intramolecular charge transfer which extends the spectral response and raises the open-circuit voltage of the resulting hetero-junction solar cells.