[Invited] Theory of Optical Properties of 2D Semiconductor Nanocrystal Lattices
Résumé
Recent progress in colloidal chemistry have led to the synthesis of new types of two-dimensional (2D) lattices of PbX (X=Se, S, Te) nanocrystals [1,2]. In these lattices, each nanocrystal is epitaxially connected to its neighbors, the 2D materials are single crystalline in absence of disorder. Remarkably, square and honeycomb lattices can be synthesized using the same initial nanocrystals, allowing to investigate the role of the lattice geometry on the electronic properties. In addition, cation exchange processes can be used to transform PbX lattices into CdX ones. Theoretical studies accompanying these experiments have already demonstrated that these 2D lattices are characterized by very interesting band structures, including in some cases Dirac and non-trivial flat bands. In the present talk, theoretical works on the optical properties of 2D lattices will be presented. The effects of the epitaxial bonds between neighbor nanocrystals on the optical properties will be discussed. The theoretical calculations will be compared to recent experimental studies [3]. The differences between IV-VI (PbX) and II-VI (CdX) materials, between square and honeycomb lattices, will be reviewed.