Advanced shape, composition, and property control in colloidal nanocrystal synthesis

Abstract

This thesis summarizes the results of 20 original publications which are covering three closely connected aspects of modern colloidal nanochemistry. The chapters included are described in the following: Chapter one gives an overview over the colloidal synthesis of nanocrystals as well as their main properties which are relevant for this thesis. Hence, important synthesis and growth parameters are discussed. The size quantization effect in semiconducting nanoparticles and the localized surface plasmon resonance effect in conductive nanoparticles are explained in depth. Chapter two of this thesis deals with different aspects of shape control of colloidal nanoparticles. The advanced shape control developed in the various original publications in chapter two shows how far beyond simple (quasi)spherical nanoparticles colloid chemical synthesis can go today. A variety of differently shaped nanoparticles like rods, branched structures but also partially hollow or concave nanoparticles are introduced. All of them could be synthesized with very low degrees of polydispersity of the particle ensembles Chapter three investigates cation exchange reactions with colloidal nanocrystals which are versatile approaches for composition control in these systems. These ion exchange reactions can either fully or also partially transform nanocrystals from one material to another without changing size or shape of the starting particles. Chapter four deals with property control in colloidal nanocrystals with a specific focus on nanoparticles with localized surface plasmon resonances in the near infrared spectral region. Here, nanoparticles from so-called degenerately doped materials are introduced as plasmonic materials which are a promising alternative for the traditional plasmonic noble metal nanoparticles. The thesis is finished by a conclusion and an outlook at future perspectives of colloid chemical nanoparticle synthesis.