Description:
Colloidal semiconductor nanocrystals, also termed quantum dots (QDs), have been discovered around 40 years ago. They have attracted considerable interest due to their size-dependent optical and electronic properties. In particular, their band gap can be simply changed by adjusting their size via the so-called quantum confinement effect. It occurs for many semiconductors when at least one of their dimensions is reduced to a few nanometers. Most research has been conducted on binary cadmium- and lead-based QDs (CdSe, PbS, etc.), which cover the visible and near infrared spectral range and can be easily synthesized. However, due to the toxicity of these compounds, their use in real-life applications is strongly limited. Our team is focusing on the development of toxic heavy metal-free and environmentally benign QDs such as III-V semiconductor materials (InP, InAs, InSb), which have a high potential for their use in biomedical applications, energy conversion, photocatalysis, and optoelectronics ^[1]. 
In this project, we want to develop a new continuous flow synthesis method for high quality III-V QDs of core and core/shell type, reduced size distribution and enhanced photoluminescence quantum yield. Continuous flow synthesis has many advantages compared to conventional batch synthesis due to the much better mass and heat transfer in tubular reactors and higher reproducibility. On the other hand, novel precursor chemistry has to be developed in order to be compatible with flow reaction requirements.
Characterization of the optical and structural properties is another central part of the project using mainly UV-vis and photoluminescence spectroscopy (both in situ and ex situ), Raman spectroscopy, NMR and FTIR spectroscopy, X-ray diffraction, elemental analysis, and electron microscopy. Finally, in collaboration with other team members and/or external partners the potential of the obtained QDs for different applications will be evaluated: in photocatalysis ^[2], near-infrared photodetectors ^[3] and LEDs ^[4].

Background and skills expected​:​
Candidates should have a strong background in materials chemistry / inorganic chemistry / chemical engineering and hold a Master degree in one of these disciplines. Hands-on experience in chemical synthesis and knowledge of optical and structural characterization techniques are further assets.

​Competences that will be acquired during the PhD:
The candidate will benefit from an interdisciplinary research environment at the cutting edge of chemistry, physics and nanoscience. He/she will be trained in the synthesis of semiconductor quantum dots using batch and flow methods, their optical and structural characterization, and will get insight in the application of these nanoparticles in various fields. In parallel, the written and oral communication skills will be trained through the participation at conferences, summer schools, as well as report, article and thesis writing.

References:
^[1] Reiss P.; Carrière, M.; Lincheneau, C.; Vaure, L.; Tamang, S., Synthesis of Semiconductor Nanocrystals, Focusing on Nontoxic and Earth-Abundant Materials. Chem. Rev. 2016, 116, 10731-10819.​
^[2] a) Kwon, H.; Kim, S.; Kang, S. B.; Bang, J., Preparation of InP quantum dots-TiO₂ nanoparticle composites with enhanced visible light induced photocatalytic activity. CrystEngComm 2022, 24 (20), 3724-3730; b) Yu, S.; Patzke, G. R. et al., Efficient photocatalytic hydrogen evolution with ligand engineered all-inorganic InP and InP/ZnS colloidal quantum dots. Nature Commun, 2018, 9 (1), 4009.​
^[3] Sun, B.; Sargent, E. H. et al., Fast Near-Infrared Photodetection Using III–V Colloidal Quantum Dots. Adv. Mater. 2022, 34 (33), 2203039.​
^[4​] a) Wood, V.; Bulović, V., Colloidal quantum dot light-emitting devices. Nano Rev 2010, 1, 5202 ; b) Yang, Z.; Li, W. et al., Recent advances in quantum dot-based light-emitting devices: Challenges and possible solutions. Mater. Today 2019, 24, 69-93.

Other information​:
Supervisor: Dr. Peter Reiss
Laboratory: CEA Grenoble, France, IRIG-SyMMES (UMR 5819)

How to apply:
Send a CV and cover letter to Peter Reiss

Starting date:
Early 2024


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