Description du sujet de thèse

Organic electronics (EO) starts to play a major role in modern electronics and will undoubtedly be part of tomorrow's electronics.(1) This new electronics is based on the use of organic semiconductors and the organic electrophosphorescent diode (PhOLED) is today the major component of this technology. A PhOLED is a device in which an emissive layer is deposited between various other layers of organic materials, all deposited between two electrodes. By applying an electric field, the PhOLED emits light by electroluminescence. In a PhOLED, the emissive layer is composed of an organic host matrix and a phosphorescent emitter organometallic complex). The operating principle is based on the generation and combination of electron-hole (exciton) pairs in the organic host and then the transfer of the excitons formed towards the phosphorescent emitter. Much of the research carried out over the past 10 years has concerned improving the properties of host matrices to make them increasingly suitable for those of phosphorescent emitters. Thus, thanks to molecular engineering works on these matrices, the performance of PhOLEDs has been increased over the years, today exceeding external quantum efficiencies of 30%.(2) Our team based at the Institute of Chemical Sciences de Rennes (ISCR) is today an internationally recognized player in this field and has published several performance records for PhOLEDs in recent years.(3-7)

However, the presence of heteroatoms (N, S, P, O…) in the molecular structure of these matrices seems to be a cause of instability in PhOLEDs (this instability being today one of the major problems in this technology) and recent studies highlight the instability of carbon-heteroatom bonds in particular.(8) In recent years, research has therefore turned to hosts made up solely of carbon and hydrogen atoms (called PHC for Pure HydroCarbon), because they have increased stability compared to hosts incorporating heteroatoms. The host team has recently reported major results in this area that highlight the feasibility of the concept.(7)
The thesis project aims to synthesize and study (electrochemistry, photophysics, molecular modeling etc) new generations of pi conjugated PHC hosts for applications in the field of blue light and white light emitting PhOLEDs which are up to date the weak links of technology. This project is at the forefront internationally and will be carried out in collaboration with the University of Soochow (Prof Z. Jiang, China) and the Institut d'Electronique et des Technologies du numeRique (IETR, Dr E. Jacques, Rennes) for the fabrication and characterization of electronic devices. This project is designed for a dynamic student with a solid background in organic chemistry and highly motivated by research on pi-conjugated systems for electronics. Knowledge and/or initial experience in analysis by electrochemistry and/or photophysics will be an asset. The PhD student will join the Condensed Matter and Electroactive Systems team of ISCR and more particularly the group led by Cyril Poriel. The thesis will be supervised by Cyril Poriel, CNRS Research Director and Cassandre Quinton, CNRS Research Officer. Applicants are encouraged to contact C. Poriel or C. Quinton for further information on this project.
References
1.Savage, N., Nature 2019, 576, S20.
2.Lin, C.-C.; Huang, M.-J.; Chiu, M.-J.; Huang, M.-P.; Chang, C.-C.; Liao, C.-Y.; Chiang, K.-M.; Shiau, Y.-J.; Chou, T.-Y.; Chu, L.-K.; Lin, H.-W.; Cheng, C.-H., Chem. Mater. 2017, 29, 1527.
3.Sicard, L. J.; Li, H.-C.; Wang, Q.; Liu, X.-Y.; Jeannin, O.; Rault-Berthelot, J.; Liao, L.-S.; Jiang, Z.-Q.; Poriel, C., Angew. Chem. Int. Ed. 2019, 58, 3848.
4.Wang, Q.; Lucas, F.; Quinton, C.; Qu, Y.-K.; Rault-Berthelot, J.; Jeannin, O.; Yang, S.-Y.; Kong, F.-C.; Kumar, S.; Liao, L.-S.; Poriel, C.; Jiang, Z.-Q., Chem. Sci. 2020, 11, 4887.
5.Poriel, C.; Quinton, C.; Lucas, F.; Rault‐Berthelot, J.; Jiang, Z. Q.; Jeannin, O., Adv. Funct. Mater. 2021, 2104980.
6.Lucas, F.; Brouillac, C.; Fall, S.; Zimmerman, N.; Tondelier, D.; Geffroy, B.; Leclerc, N.; Heiser, T.; Lebreton, C.; Jacques, E.; Quinton, C.; Rault-Berthelot, J.; Poriel, C., Chem. Mater. 2022, 34, 8345.
7.Kong, F. C.; Zhang, Y. L.; Quinton, C.; McIntosh, N.; Yang, S. Y.; Rault-Berthelot, J.; Lucas, F.; Brouillac, C.; Jeannin, O.; Cornil, J.; Jiang, Z. Q.; Liao, L. S.; Poriel, C., Angew Chem Int Ed Engl 2022, 61, e202207204.
8.Li, H.; Hong, M.; Scarpaci, A.; He, X.; Risko, C.; Sears, J. S.; Barlow, S.; Winget, P.; Marder, S. R.; Kim, D.; Brédas, J.-L., Chem. Mater. 2019, 31, 1507.

Contexte de travail

The PhD student will join the Condensed Matter and Electroactive Systems team of ISCR , campus de Beaulieu , University of RENNES.
The thesis will be supervised by Cyril Poriel, CNRS Research Director and Cassandre Quinton, Senior CNRS Researcher.
Diploma : master in Chemistry
Skills : technical and theoretical skills in organic Chemistry
Writing in France and english

Contraintes et risques

Health and Safety constraints related to work in an organic synthesis laboratory.