Year: 2025
Type: article
Abstract: One of the main interests of 2D materials is their ability to be assembled with many degrees of freedom for tuning and manipulating excitonic properties. There is a need to understand how the structure of the interfaces between atomic layers influences exciton properties. Here we use cathodoluminescence and time-resolved cathodoluminescence experiments to study how excitons interact with the interface between two twisted hexagonal boron nitride ( h -BN) crystals with various angles. An efficient capture of free excitons by the interface is demonstrated, which leads to a population of long-lived and interface-localized (2D) excitons. Temperature-dependent experiments indicate that for high twist angles, these excitons localized at the interface further undergo a self-trapping. It consists in a distortion of the lattice around the exciton on which the exciton traps itself. Our results suggest that this exciton-interface interaction causes the broad 4-eV optical emission of highly twisted h -BN– h -BN structures. Exciton self-trapping is finally discussed as a common feature of s p 2 hybridized boron nitride polytypes and nanostructures due to the ionic nature of the B—N bond and the small size of their excitons.
Source: Physical Review X
Authors: Sébastien Roux, Christophe Arnold, Etienne Carré, Alexandre Plaud, Lei Ren, Frédéric Fossard, Nicolas Horezan, Eli Janzen, James H. Edgar, Camille Maestre, Bérangère Toury, Catherine Journet, Vincent Garnier, Philippe Steyer, Takashi Taniguchi, Kenji Watanabe, Cédric Robert, Xavier Marie, François Ducastelle, Annick Loiseau, Julien Barjon
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,200
OpenAlex ID: W4410774232