En poursuivant votre navigation, vous acceptez l'utilisation de cookies destinés à améliorer la performance de ce site et à vous proposer des services et contenus personnalisés.

X

Orgatech - Organic Materials

Overview
The synthesis of multi-functional emissive, organic materials was initiated in the framework of the Orgatech platform as a new activity in 2011.

The activity was initiated thanks to the motivation of  two CNRS researchers who chose to join our team.
Three kinds of specific innovative materials were investigated:
 
Luminiscent and Magnetic Materials
Recently, a highly luminescent europium complex was isolated.

When implemented as dopant in a PMMA thin film, it emits a strong red light with a quantum yield of 80%. This is one of the highest values reported so far.
 

Schematic representation showing the charge transfert mechanism in Lanthanide-containing metallopolymers specifically designed for OLED applications (top pannel). The pictures show a blue-emitting polymer prepared in solution (left) and thin film deposited on a transparent glass (right). Pictures are taken under UV light illumination.
 
We also studied molecular complexes of the lanthanide ions in the field of molecular magnetism

These magnetic compounds are of interest as active materials for information storage devices.

Conjugated Polymers
- We work on the synthesis of blue-emitting electroluminiscent materials. We have obtined Polymers with a quantum yield of 50%.
- We have synthesized various families of functionalized polymers  functionalized with charge-transporting groups. They are expected to improve charge carrier transport and lead to a good balance between positive and negative charge carriers within the device, which is crucial for high electroluminescence efficiency.

- We started to develop a new family of materials, namely conjugated metallopolymers.
- Through chemical engineering, they were anticipated to present interesting properties for designing electroluminescent devices with simplified structures and tunable colors.

- We also use conjugated polymers to promote the formation of thermodynamic stable microdomain morfologies. This approach has gained interest to solve problems related to phase separation in solar cells based on bulk heterojunction (BHJ).
- Random and diblock copolymer Poly(3-hexylthiophene) block poly[3-(3-(6-ethyl-ethoxy-pentanoate) thiophene], P3HTco- P3AcidHT and P3HT-b-P3AcidHT were designed with molecular weights of each of the two blocks that encourage well-defined nanostructures and enhance morphological stability.
- Cooperative self-assembly and favorable hydrogen bonding interactions between the COOH-functionalized block copolymers and the ester side chain of PCBM allow to form finer nano-phase separation and self-assembly into an interpenetrating network with 10–20 nm crystalline copolymer domains.
- BHJ solar cells prepared using P3HT-b P3AcidHT/PCBM exhibit a photoconversion efficiency of 4.2%, which is higher than that of reference systems: P3HT/PCBM and P3HT-co-P3AcidHT /PCBM.

Chemical Structures of P3HT-b-P3AcidHT/PCBM and schematic of the ordered, self-assembled blend that serves as the active layer in the OPV Devices.
 
- Efforts have been directed at extending the absorption of polymer to longer wavelengths with novel functional copolymers.
- A series of evolving frontier energy levels and gaps, 4-difluoro-cyclopenta[2,1-b:3,4-b′] dithiophene and isoDPP accepting building blocks have been synthetized and copolymerized with various donor moieties. 
- A range of HOMO/LUMO levels and energy gaps were achieved in these new polymers. DSC and X-ray diffraction (XRD) investigations revealed that:
  1. linear alkyl chain substituents promote the formation of ordered layered structures.
  2. branched alkyl chains lead to amorphous materials. 
- Preliminarily polymer solar cells based on these copolymers as donor and PCBM as acceptor components are under investigation.
 

 X-ray diffraction images of copolymers: a) P1, b) P2, c) P3 and d) P4.

Sol-gel materials
-Third class of materials we started to investigate for photon emission purposes.
-They are easy to be processed because of their physico-chemical properties.

- The aim was to check their potential use as electroluminescent materials as well as hybrid visible emitting phosphors for lighting applications, with a special interest for the generation of white light.
- Blue, green, red, and white emissive materials have already been isolated.
-This paves the way to the whole panel of visible colors.