Proceedings of nanoGe Spring Meeting 2022 (NSM22)
DOI: https://doi.org/10.29363/nanoge.nsm.2022.087
Publication date: 7th February 2022
Colloidal semiconductor heteronanocrystals (HNCs) exhibit unique optoelectronic properties that are inaccessible to single-component NCs, making them promising materials for a wide range of applications. The optoelectronic properties of HNCs are determined not only by the bandgap and band alignment of its constituent materials but also by their morphology and heteroarchitecture [1]. Applications requiring efficient charge separation (e.g., photovoltaics and photocatalysis) greatly benefit from anisotropic morphologies, such as heteronanorods. Most of the work on heteronanorods has focused on Cd-chalcogenide-based HNCs. However, given the toxicity of Cd, the potential of these materials for large scale applications is limited.
Copper-chalcogenide based NCs have attracted increasing attention as promising alternatives for Cd- and Pb-chalcogenide NCs due to their low toxicity, large absorption cross-sections across a broad spectral range, composition-dependent band gaps in the 1 to 2.5 eV range, and photoluminescence tunability, spanning a spectral window that extends from the UV to the NIR depending on the NC size and composition [2,3].
Several synthetic strategies have been used in the quest for high-quality colloidal copper chalcogenide based HNCs. The most promising ones are based on the multistage approach, which allows the combination of different synthesis techniques (e.g., cation exchange [4,5] or seeded growth [6-9]) in a sequential manner in order to achieve the targeted preparation of colloidal HNCs. In this talk, I will discuss a selection of recent examples, chosen in order to provide an overview of the current status of the quest for Cd- and Pb-free HNCs and to illustrate specific synthesis strategies: CuInSe2/CuInS2 dot core/rod shell heteronanorods [4], Cu1.8S-based multicomponent axially segmented heteronanorods [5], CuInS2/ZnS dot core/rod shell heteronanorods [6], and Janus-type Cu2‒xS/CuInS2 and Cu2−xS/ZnS heteronanorods [8,9]. I will show that by combining the design principles of post-synthetic heteroepitaxial seeded growth and nanoscale cation exchange into multistage synthesis strategies one can potentially gain access to a plethora of Cu-chalcogenide-basedmulticomponent heteronanorods with diameters in the quantum confinement regime.