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Localized Surface Plasmon Resonance in doped semiconductor nanocrystals

Periodic Reporting for period 2 - SONAR (Localized Surface Plasmon Resonance in doped semiconductor nanocrystals)

Reporting period: 2019-01-01 to 2022-12-31

SONAR aims to give a clear picture of the interaction between infrared plasmonic nanomaterials and two-dimensional materials as graphene or transition metal dichalcogenides.
Within SONAR the objectives are:
- to explore fundamentals in doped semiconductor nanocrystals (dSNCs) including various different materials, sizes, shapes, their doping mechanism, their general dielectric properties, the case of ultralow doping, and interactions between the LSPR and the interband transition;
- to exploit hybrid interactions of dSNCs to investigate exciton-plasmon, plasmon-plasmon coupling or plasmon induced ‘hot’ electron transfer and explore dSNCs for the manipulation of layered two dimensional materials;
- to exploit the characteristics of dSNCs for optical devices such as electrochromics, electro-tunable light emitters, or tunable NIR photodetectors.

We have published a broad review in Physics Reports entitled “Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives” that aims to make a library of all the recently reported plasmonic doped semiconductor nanocrystals. We have also demonstrated the ultrafast switching of a doped metal oxide based photonic structure. Moreover, we reported several studies that answer important questions on the exciton and charge dynamics of two-dimensional materials.

The achievements in SONAR are important for the society since these findings are necessary for the engineering of electrochromic windows, novel light emitters and near infrared detector.
We have collected and analysed all the recent results in plasmonic doped semiconductor nanocrystals and one-dimensional photonic structures, reporting these findings in two broad and well cited review papers in Physics Reports and Optical Materials.
With plasmonic doped semiconductor nanocrystals we have performed different types of doping tunability: electrochemical doping and photodoping with indium tin oxide nanocrystals, ambipolar doping with gallium iron oxide nanocrystals.
With indium tin oxide embedded in one-dimensional photonic structures we have demonstrated continuous wave photodoping and ultrafast photodoping with femtosecond pulses.
We have pursued a work that combines a microscopic theory with ultrafast pump-probe experiments to reveal a new low-intensity saturation regime in graphene.
We have performed a theoretical analysis that suggests the fluorine indium codoped cadmium oxide nanocrystal (a dSNC) based layers to modulate with light a 1D photonic crystal.
With the combination of ultrafast spectroscopy and theoretical models, we have studied the formation of excitons in a two-dimensional material, such as molybdenum disulphide.
Promising results have been achieved with doped semiconductor nanocrystal / semiconductor heterojunctions.
Within SONAR we did answer fundamental questions about the ultrafast dynamics in two-dimensional materials as graphene e transition metal dichalcogenides. We have erlarged the possibilities to tune the plasmon resonances in doped semiconductor nanocrystals. Finally, we exploited the photodoping of indium tin oxide nanocrystals to fabricate light controllable devices.
The exploitation of these findings can be very important for the fabrication of new types of photonic devices for tunable light emission, new types of photodetectors. Moreover, a clear understanding of the charge generation in doped semiconductor nanocrystal / semiconductor junctions can lead to the fabrication of efficient solar devices based on the hot electron transfer mechanism by absorbing the infrared part of the Sun irradiation, which is the 45% of the total Sun irradiation and which is not absorbed by most photovoltaic materials.
Transmission electron microscopy image of FICO nanocrystals
Outreach at Montessori School
Experiments during outreach activities