Exciton Transfer in Array of Epitaxially Connected Nanocrystals

Recently, epitaxially connected at facets semiconductor nanocrystals (NCs) have been introduced to fascilitate the electron transport between nanocrystals. To fully deploy their potential a better understanding of the exciton transfer between connected NCs is needed. We go beyond the two well-known transfer mechanisms suggested by F\"orster and Dexter and propose a third mechanism of exciton tandem tunneling. The tandem tunnelling occurs through the intermediate state in which electron and hole are in different NCs. The corresponding rate for exciton hops is larger than the Dexter rate and for Si is even much larger that the F\"orster one.