π-conjugated (macro-) molecules or electronic conductive polymers

We use π-conjugated (macro-) molecules mainly for their electron conduction or hole properties in applications often related to energy storage and conversion.

Thus, the LPPI synthesizes new molecular glasses (MG), which are type p semi-conductors and amorphous at room temperature.

In addition, photoactive π-conjugated molecules associated with a porous TiO₂ substrate allow a variation in the contact angle of the water on this hybrid material, that is both large (greater than 100°) and fast (~1 minute) during UV/visible illumination cycles illustrating a modulatable surface wetting.

π -conjugated macromolecules investigated in the laboratory are mainly polythiophene derivatives used either alone or in combination with organic or inorganic materials. Due to their unusual electronic structure, these polymers are semi-conductive in the neutral state and conductive in oxidized state while their optical properties are also modified during the oxidation reaction. This relation was exploited to develop electrochromic polymers. When these π-conjugated polymers are developed as thick films, they also have interesting optical properties in the infrared field. Totally opaque in this spectral domain in the neutral state, they become reflectors once oxidized. This property is used to develop variable and reversible IR reflectivity devices.

Finally, the redox process in pi-conjugated polymers involves an electronic transfer that induces movement of ion species that can conserve local electroneutrality. Ion exchange between macromolecules and the electrolyte induces a volume variation of the pi-conjugated polymer. By intensifying this process, it is possible to transform electrical energy into mechanical work through the oxydo-reduction reaction: this is the domain of actuators.