Energy-Transfer-Induced Enhanced Valley Splitting of Excitonic Emission of Inorganic CdTe@ZnS QDs in the Presence of Organic J-Aggregates: A Spectroscopic Insight into the Efficient Exciton (Inorganic)-Exciton (Organic) Coupling

An inorganic-organic nanohybrid material comprising an inorganic exciton (CdTe@ZnS) and an organic exciton (J-aggregates) has been synthesized, and subsequently investigations on exciton-exciton coupling between two components of the materials are carried out by employing various spectroscopic techniques. Analysis of the data has revealed very high Förster-type resonance energy transfer (FRET) from the donor quantum dots (QDs) to the acceptor J-aggregates. Interestingly, a clear splitting of the QD emission band during the FRET event is observed, indicating efficient coupling between inorganic and organic excitons. The observation of valley splitting of QD emission by organic J-aggregates, even in the absence of an external field, is new and exciting. More interestingly, the investigations have also shown that the valley splitting of the QD emission can be controlled by regulating the FRET process. In fact, a linear relationship between the energy separation value of the valley splitting and the FRET efficiency between QDs and J-aggregates is obtained. Moreover, in the present hybrid system, the presence of an organic moiety becomes advantageous in the sense that the valley splitting can also be controlled easily through chemical modification of the organic moiety. The outcome of the present investigation essentially demonstrates that the present nanohybrid system can be considered as a potential candidate for the fabrication of valleytronic materials.