Top-down Approach for the Direct Synthesis, Patterning, and Operation of Artificial Micromuscles on Flexible Substrates

Recent progress in the field of microsystems on flexible substrates raises the need for alternatives to the stiffness of classical actuation technologies. This paper reports a top-down process to microfabricate soft conducting polymer actuators on substrates on which they ultimately operate. The bending microactuators were fabricated by sequentially stacking layers using a layer polymerization by layer polymerization of conducting polymer electrodes and a solid polymer electrolyte. Standalone microbeams thinner than 10 μm were fabricated on SU-8 substrates associated with a bottom gold electrical contact. The operation of microactuators was demonstrated in air and at low voltage (±4 V)

Processable Star-Shaped Molecules with Triphenylamine Core as Hole-Transporting Materials: Experimental and Theoretical Approach

In this study we report on the characterization of five star-shaped π-conjugated molecules by means of UV–vis absorption spectroscopy and electrochemical cyclic voltammetry. These molecules, with triphenylamine (TPA) core bearing one thienothiophene moiety and a different number of thiophene ones, are designed as hole-transporting materials for dye-sensitized solar cell (DSSC) applications. Theoretical calculations employing the B3LYP functional are also carried out in order to understand the structure–property relationships. UV–vis absorption measurements and time-dependent density functional theory (TDDFT) calculations show the presence of intense UV–vis bands for all compounds. These bands are dominated by two degenerate π–π* excitations mostly involving the HOMO → LUMO and HOMO → LUMO+1 transitions. Electrochemical cyclic voltammetry and DFT calculations show the HOMO (LUMO) energy levels increasing (decreasing) with the number of conjugated heterocyclic rings in these molecules. The HOMO energies have been found to vary between −5.38 and −5.13 eV thus showing good positioning with respect to the Fermi level of gold electrode (DSSC applications). The calculated internal reorganization energies (λ_i) suggest for these materials promising hole-transport properties. The analysis of the space extension of the HOMO orbitals as a function of the number of conjugated rings in these molecules gives useful information on their design