Thien-Phap NGUYEN

Organic light emitting diodes (LEDs) now appear as a promising application of conjugated polymers. Indeed, the use of polymers or organic materials as active layer in the LEDs makes it possible to obtain specific properties inaccessible to inorganic LEDs: low mass, flexibility, large active area, high luminosity.

We realize the light-emitting diodes based on polymer and organic material and study the different physico-chemical phenomena involved in the operation of LEDs: characterization of active materials, conduction mechanisms in devices, role of interfaces in charge injections , Structure of these interfaces, and degradation phenomena. Based on the knowledge gained from these studies, we design strategies for improving the performance of diodes and apply them to the study of devices using new materials and new structures. On the one hand, a better understanding of the functioning of the diodes has been gained by the appropriate characterization methods (trapping, conduction, degradation.) On the other hand, improvements in the performance of the devices have been achieved. Characterization and electrical analysis of organic semiconductors to model the conduction and transport processes in the studied electronic devices.

Patricia Bertoncini, Olivier Chauvet

We are interested in the coupling between Single-walled Carbon nanotubes (SWNT) and photosensitive biological systems. So, we synthesized SWNT / light-harvesting proteins (such as bacteriorhodopsin or C-Phycocyanin) hybrids by immobilizing the proteins on the sidewall of the nanotubes, characterized their morphology, explored their optical and fluorescence properties. We show that radiative and non-radiative energy transfers from proteins to SWNTs can occur in these hybrids. We attribute importance to the understanding of the interactions between the CNTs and the biological systems involved and to the study of the conformational changes of the biomolecules that can occur.