Order and interactions in colloidal nanoparticle superlattices

• Applicant: Professor Dr. Holger Lange
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2011 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 189145350

Recently, ordered structures of colloidal nanoparticles have gained much attention.1–4 The assembly of small nanoparticles into macroscopic structures is an important topic in chemistry and materials science. The combination of nanoparticles of different materials into a nanoparticle superlattice can result in a large variety of materials (metamaterials) with controlled chemical composition. The possibility to control the nanoparticle size, shape and composition allows the tuning of the electronic, optical and magnetic properties of these building blocks. Ensembles of nanoparticles can display new electronic, magnetic and optical properties as a result of interactions between the excitons, magnetic moments or surface plasmons of individual nanoparticles.1, 4, 5 The contact distances, contact areas, the interparticle forces and interactions in such structures are important for the control of these properties. This project aims to investigate the interactions between the individual colloidal nanoparticles in nanoparticle superlattices, which are crucial for many applications and not yet sufficiently understood. Conglomerates of nanoparticles and single ordered layers of nanoparticles will be investigated by tip-enhanced Raman measurements. This will lead to fundamental knowledge of the influence of the particle size and nature on the interactions between the particles. Measuring the vibrations of superlattices will give an insight into the order of the superlattice and the strength and nature of the coupling between the particles. The measurements will be accompanied by ab-initio, boundary element method and molecular dynamics calculations. This will lead to a general understanding of the coupling mechanisms within these structures, which is of great importance for the further development and integration of these emerging materials.

• DFG Programme: Research Grants