Design of NPLs from the Inorganic Core to the Surface Chemistry

II-VI semiconductor nanoplatelets are colloidal nanoparticles confined in one dimension which gives them exceptionally narrow optical properties. We are showing that through the design of core/crown/crown heterostructures, it is possible to synthesize nanoplatelets with green and red emissions from a single population. In the CdSe/CdTe/CdSe core/crown/crown NPLs, the exciton either recombine at the interface between 2 semiconductors due to the type II band alignment or in the CdSe area. The ratio of the two emissions can be tuned by the incident power. With increased power, the red emission saturates due to non-radiative Auger recombination thus affecting its emission much stronger than the green one. These NPLs can be introduced in LED. So, the design of the NPLs inorganic core enables to tune their optical properties but their shape can be further modified through the surface chemistry. NPLs with their large lateral dimensions can be considered as flexible substrate for the self-assembly of ligands which originally ensure the colloidal stability of NPLs. The stress brought by surface ligands and the specific zinc blende crystal structure of the NPLs induce a folding of NPLs as helices or twists. We show that an exchange from carboxylate ligands to halides ligands and thiolate ligands enable to unfold CdSe NPLs and to invert the chirality of the helices.