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Reference : UMR7588-LAUCOO-002
Workplace : PARIS 05
Date of publication : Wednesday, April 28, 2021
Scientific Responsible name : Laurent Coolen
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
While fluorescence from isolated emitters is now well known, most opto-electronic applications (LEDs, solar cells…) involve nanoparticles packed in a dense layer, where they should behave very differently because of short-range interactions, charge transport and exciton diffusion between neighboring particles. By using adequate solvent and ligands, the group of B. Abécassis in ENS Lyon has managed to self-assemble chains of hundreds of semiconductor nanoplatelets which constitute a good model system for nanoparticles interactions. We have shown that, due to near-field dipole-dipole Förster-type interactions (FRET), excitons migrate extremely fast between platelets so that the fluorescence behavior of assembled platelets is expected to show collective effects instead of only being the sum of the luminescence of each platelet.
The aim of the PhD work is to determine
- how the assembly geometry affects the FRET exciton transfers,
- to which extent FRET induces collective fluorescence effects (intensity fluctuations, multi-excitonic effects),
- and whether this ensemble of light emitters can show enhanced radiation by nano-lasing or by interfering constructively with each other (superradiance).
We will examine different configurations of emitters assembly : chains of different platelet distances, platelets with chiral ligands, nanorods assembled by liquid crystals. In order to optimize light-matter coupling, the assembled particles will be coupled to plasmonic nano-antennas.
References (recent work of the group) :
Fu Feng et al., ACS Photonics 5, 1994 (2018)
Fu Feng et al., Nano Research 11, 3593 (2018)
Jiawen Liu et al., Nano Lett. 20, 3465 (2020)
Jiawen Liu et al., ACS Photonics (2020)
The PhD student will be registered at the Ecole doctorale 564 : « Physics in Ile-de-France » (Ile-de-France = Paris region) and will lead his.her research work at the Institute of NanoSciences of Paris (INSP, UMR 7588), a joint research unit of CNRS and Sorbonne Université. The institute is dedicated to fundamental scientific inquiry in nanosciences with applications in a wide range of fields such as optoelectronics and telecommunications, earth and environmental sciences, catalysis and medical diagnosis.
The research at the INSP aims to identify and understand the new properties that arise when physical phenomena are confined within objects that are smaller than their characteristic lengthscale. In particular research is centred on the control and measurement of the interface between these small objects and their surrounding environment. The general activity is to evidence and understand the new properties that arise whenever physical phenomena are confined within objects that are smaller than their characteristic lengthscale. In particular, research is centered on the control and measurement of the interface between these small objects and their surrounding environment. The laboratory's facilities are located on campus Pierre et Marie Curie, place Jussieu (Paris 5th).
The thesis is funded by the ANR FOENICS project led by INSP, in collaboration with the ENS of Lyon (resp. B. Abécassis) for the development of new assembly protocols of the platelets.
Constraints and risks
The thesis work, which is mainly experimental, will occur in accordance with the rules of laser safety, cryogenic fluids manipulation and chemical products manipulation.
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