Tuning of photo‐ and electroluminescence in alkylated polythiophenes with well‐defined regioregularity

Color tuning of luminescence via molecular engineering of the Active polymer is important for the commercial application of pi-conjugated polymers in photonic devices. The synthesis of a series of regiospecific alkylated polythiophenes is described. in which the effective conjugation length could be varied by altering the length of the coplanar blocks between head-to-head dyads. It is demonstrated that the color-tuned materials obtained by this novel approach are potentially suitable for application in displays and other devices

Photorefractivity in poly(N-vinylcarbazole)-based polymer composites

The mechanism of photorefractivity in a family of model composites based on PVK is discussed. Novel aspects of photorefractivity that are unique in polymers are described. The effect of plasticization on their photorefractive performance is investigated.

Correlation between growth parameters and thermoelectric efficiency of PEDOT-Tos thin films for energy harvesting applications

For years, materials are competing for the best thermoelectric properties through the enhancement of the figure of merit ZT. After metals and semiconductors, oxides and polymers are today in the front. In the same time, the way to evaluate the ZT property is often a problem because of the plural techniques and systems of measurement.The last development in the laboratory consists in a complete setup for the simultaneous evaluation of the Seebeck coefficient, electrical and thermal properties of the thermoelectric material, that we call ZT-meter. With this microscale device, we performed a deeply analysis of the thermoelectric behaviour of concerned materials.Evolving in a national project called Tours2015, we are actually studying different sputtered PEDOT-Tos polymer thin films deposited on silicon, in order to correlate the growth parameters with the thermoelectric properties. With ZT values expected above 0.2, these materials could be serious candidates to be used later on as a new micro-source of energy

Nanostructure of self-assembled rod-coil block copolymer films for photovoltaic applications

The nanostructures of a series of rod-coil block copolymers, designed for photovoltaic applications, are studied by atomic force microscopy and transmission electron microscopy. The copolymers are composed of a semiconducting poly-p-phenylenevinylene rod with (2'-ethyl)-hexyloxy side chains and a functionalized coil block of various length and flexibility. Both, as deposited and annealed block copolymer films were investigated. The results show that highly ordered structures are only obtained if the coil block is characterized by a glass transition temperature which is significantly lower than the melting temperature of the alkyl side chains. For this material a high molecular mobility and strong driving force for crystallization of the rigid block can be achieved simultaneously. For the smallest coil to rod length ratio, we found a lamellar morphology with perpendicularly oriented lamellae with respect to the substrate. Electron diffraction data show the presence of a periodical molecular arrangement with a characteristic distance of 0.94 nm that is attributed to the distance between conjugated chains separated by the layers of alkyl sidechains