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Beschreibung:
The transformation of intricate nanocrystals (NCs) available through colloidal chemical synthesis into branched network structures (referred to as gels) presents a promising pathway to macroscopic solids exhibiting properties of their NC building blocks. In this work, the possibilities to influence these properties at various stages during the gel synthesis sequence will be explored and expanded on. Additionally, the nanoscopic (opto-)electronic properties of networks build up from semiconducting, photoluminescent (PL) NCs will be investigated to gather insights into the electronic structure of such networks and the dynamics of excited charge carriers therein. In chapter 5 the investigation of gel networks based on CdSe/CdS dot/rod NC building blocks is shown. The PL properties of such structures are analysed in regards to their temperature and time dependent emission (down to 4K). It is shown that at cryogenic temperature the emission splits into two discernible processes correlating to dark and bright exciton states. While this observation is comparable to the results obtained for individual NCs, at all temperatures gel networks exhibit a longer PL decay most likely caused by increased electron delocalization. The investigation also includes a look at differently sized CdSe cores used for synthesis of the CdSe/CdS dot/rod building blocks. It is found that the combination of different core sizes and therefore different emission color building blocks allows for straight-forward color tuning of the final networks. The modification of NC-based gels with thin metal oxide shells is shown in chapter 6. Importantly, NC-based aerogels can be influenced not only at the point of NC building block synthesis but also after the gel formation (post-gelation). In this work, the application of wet-chemical methods based on colloidal seeded-growth processes to a NC-based gel network substrate is presented. This results in uniform, thin shells over the whole of the gel network. The approach can be shown to work on different gel ...