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Tuan-Minh Duong

Development of perovskite quantum dots for all-optical quantum information technology and spintronics

Published on 3 March 2023
Thesis presented March 03, 2023

Lead halide perovskites have received great research interest in the past decade thanks to their excellent optoelectronic properties. Initially studied by the photovoltaic community, the material quickly became popular in quantum dots research after reliable synthetic routes to high-quality perovskite nanocrystals were devised. One important research direction for these nanocrystals is quantum technology. As devices operate with the principles of quantum mechanics, quantum-confined nanocrystals will become an essential component, with applications in single photon sources and spintronics. In a single photon source, a single nanocrystal plays the role of the emitter, and by proper excitation as well as the design of the surrounding medium, single photons can be emitted at determined interval and direction. In contrast to single photon sources, where only the intrinsic optical properties of nanocrystals are concerned, the use of nanocrystals in spintronics depends on the effects resulting from doping the particles with magnetic ions and creating a class of material known as diluted magnetic semiconductors. For lead halide perovskites, only a limited number of studies have been conducted compared to II-VI and III-V semiconductors. However, the research on perovskites, especially nanocrystals, is challenged by the poor stability of the materials. Therefore, this thesis has been carried out with the aim to passivate lead halide perovskite nanocrystals on a single particle level with an oxide shell, then study their integration into a single photon source structure known as nanopatch antenna, and their magneto-optical properties when doped with Mn2+ ions. The major results were i) the successful overgrowth of CsPbBr3 nanocrystals with a homogeneous alumina shell, which led to an improvement of their photostability when used in a photonic structure with silver nanocubes acting as antenna; ii) the doping of CsPbBr3 nanocrystals with aluminum, giving rise to a controllable blue-shift of the absorption and emission spectra; iii) the controlled doping of CsPbBr3 nanocrystals with Mn2+ and the study of the magneto-optical properties.

halide perovskite nanocrystals, doping, single-photon emitters, diluted magnetic semiconductors