The research focused on the chemical synthesis and photophysics of 2D colloidal nanocrystals, in particular CdSe nanoplatelets and transition metal dichalcogenide nanosheets.
For CdSe nanoplatelets, we were able to cover the emission range from the UV to the near-infrared, by developing several highly fluorescent 2D nanocrystals. In particular, we developed protocols to synthesize CdSe nanoplatelets with variable thickness and emission ranging from the UV (400 nm) to the red (625 nm). In addition, by incorporating silver into the CdSe nanoplatelets, we extended this to the near-infrared (880 nm).
The growth of heterostructures resulted in an engineering of the band structure, yielding fluorescence upconversion of red and infrared excitation light into green emission, as well as efficient stimulated emission from blue-emitting nanoplatelets.
The photophysics of excitons and biexcitons in 2D nanocrystals where investigated with transient absorption spectroscopy, revealing their oscillator strength, binding energy, lifetime and, for highly excited nanoplatelets, the optical gain coefficient an lifetime. Results yielded both new insights into the 2D nanocrystal optoelectronic properties and demonstrated that they are efficient gain materials.
Regarding Cd-free alternatives, we developed a library of synthesis protocols for MX2 (M=Mo, W; X= S, Se) transition-metal dichalcogenide nanosheets, with a thickness down to a single monolayer, a prerequisite for obtaining a direct-gap semiconductor. As a result, MoX2 monolayers already displayed fluorescence from 4K up to room temperature.
Results where disseminated in scientific journals and conferences, as well as on social media and via press releases.
