You are here : Home > LEMMA team > Advanced TEM studies on colloidal semiconductor nanocrystals

Fabio Agnese

Advanced TEM studies on colloidal semiconductor nanocrystals

Published on 16 October 2018
Thesis presented October 16, 2018

Abstract :
Colloidal nanocrystals have important potential applications in different technological fields such as solar cells and thermoelectricity, thanks to their reduced fabrication costs and exotic and unique properties. In this thesis, a variety of advanced transmission electron microscopy (TEM) techniques is used to unravel the morphology, crystal structure and chemical composition of state-of-the-art Cu2ZnSnS4 (CZTS) and CsPbBr3 and CuFeS2 colloidal nanocrystals.
Firstly, the difficulties of these TEM observations and the found solutions are presented.
Then the details of the various TEM observations, such as Energy Dispersion X-ray (EDX) spectroscopy, High Resolution Transmission Electron Microscopy (HR-TEM), High Resolution Scanning TEM(HR-STEM) and Nanobeam Precession Electron Diffraction (NPED) are exposed and compared to synchrotron Small-Angle X-ray Scattering (SAXS) and Wide-Angle X-ray Scattering (WAXS) experiments.
For CZTS, different samples extracted at different times of the fabrication have been observed and a growth mechanism is proposed. For CsPbBr3, the focus was put on the determination of the exact structure, cubic or orthorhombic, of the nano-crystals. For CuFeS2, the influence of synthesis methods on the morphology and crystal structure are presented in an appendix.

TEM, nanocrystal, colloidal nanocrystals, Perovskite, Core/shell, Czts, Nanoparticles, Stem.

Thèse en ligne.