Direct enhancement of luminescence of CdxZn1−xSeyS1−y/ZnS nanocrystals with gradient chemical composition by plasmonic nanoantennas

• Published in: Optics and laser technology 2020-01, Vol.121, p.105821, Article 105821
• Main Authors: Toropov, Nikita A., Kamalieva, Aisylu N., Volkov, Roman O., Kolesova, Ekaterina P., Volgina, Dominika-Olga A., Cherevkov, Sergey A., Dubavik, Aliaksei, Vartanyan, Tigran A.
• Format: Article
• Language: English
• Subjects: Absorption; Alloying; Cadmium selenides; Chemical composition; Composition effects; Enhancement; Excitons; Fluorescence; Hybrid structures; Luminescence; Nanoantennas; Nanocrystals; Nanoparticles; Nanostructure; Near fields; Organic chemistry; Photonics; Plasmon; Purcell effect; Quantum dot; Quantum dots; Quenching; Silver; Thin films; Transition layers; Zinc sulfide
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2019.105821

[Display omitted] •Fluorescence of new nanocrystals was studied in the near field of plasmonic antennas.•Upon their direct contact fluorescence enhancement was observed.•That was explained by the Purcell effect. Flat photonic materials such as thin films or metasurfaces form the basis of new optics and laser technology. However, their characteristics, for example, absorption and luminescence, are drastically limited in contrast to bulk materials. This problem can be overcome using plasmonic nanostructures. While the quantum dots absorption is enhanced by the plasmonic nanostructure near fields in almost all circumstances, more sophisticated approaches are needed to obtain the fluorescent enhancement because of the concurrent quenching by the metallic surface. Here we report on the results of an illustrative experiment demonstrating the luminescence enhancement of a new type of semiconductor nanocrystals CdxZn1−xSeyS1−y/ZnS (alloyed quantum dots) at their direct contact with a monolayer of silver nanoparticles. This type of nanocrystals consists of a CdSe core, a ZnS shell, and a transition layer in between where the composition smoothly changes, thus representing an alloy with variable x and y. We found that at the resonant plasmon–exciton coupling of such nanostructures, the fluorescence enhancement is accompanied by the reduction of the luminescence decay time – the main signature of the Purcell effect. Unlike previously studied compositions, these new hybrid structures do not require additional components to avoid fluorescence quenching which is promising for practical applications in flat optical devices.