Formation and Charge Carrier Dynamics of Hybrid I-III-VI2 Nanoheterostructures

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I-III-VI2 semiconductors line CuInS2 are promising materials, because they do not contain toxic heavy metals like CdSe, PbS or methylammonium lead perovskites. However, in form of nanocrystals the photo-physics if I-III-VI2 semiconductors is not yet well understood, because excited charge carriers tend to localise at intrinsic defects instead of assuming an excitonic state defined by the particle size. There exist different models for the charge carrier dynamics in I-III-VI2 semiconductors, but none of them could have been unambiguously proven or disproven. To test these models and identify the charge carrier dynamics of I-III-VI2 semiconductors the synthesis of heterostructures is proposed, in which the material under investigation shares an interface with a well-characterised, second material. The interface is chosen in such a way that the excited electrons and holes get spatially separated. This way it will be possible to quantify their contributions to the charge carrier dynamics and test the different models. Additionally, this project will yield information on the mobility of monovalent cations in the ternary compounds through the formation of the heterointerface. This quantity is important both for the fabrication and characterisation of the heterostructures and for the dynamics of the intrinsic defects. The analysis of cation and charge carrier dynamics contributes significantly to a fundamental understanding of nanocrystalline semiconductors and the technical use of these promising materials for applications in energy production and storage. The project establishes the model system of two materials in electronic contact for the general investigation of charge carrier dynamics.