Session: Colloidal Nanoparticle Synthesis and Assembly:

The optoelectronic and chemical properties of semiconductor nanocrystals depend on their composition, size, shape and surface functionality. Cadmium telluride nanoplatelets (CdTe NPLs) are one of these semiconductor nanocrystals which, because of their relatively small bandgap (E_g = 1.44 eV) in bulk CdTe, are considered a promising material for photonic applications across the visible and near-infrared spectral range. Colloidal synthesis is a powerful strategy to alter the NPL optoelectronic and chemical properties, yet most efforts have been dedicated to CdSe NPLs. In this work, we focused on the synthesis of size-controlled CdTe NPLs, and show that the chemical reactivity of the tellurium precursor plays a role in controlling the area of 3.5 monolayer (ML) CdTe NPLs. In addition, we investigated the effects of additives to the reaction mixture, such as oleic acid, acetic acid and water. Our results show that there is an optimal combination of additives that reduces the NPL area to a minimum. This benefits the fluorescence quantum efficiency (PL QE), as we observed an inverse relationship between the NPL area and the PL QE. Finally, we obtained 3.5 ML CdTe NPLs with up to 5% PL QE, and a reduced trap band emission.

Fadi AL-Shnani

Phd student, Ghent University

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