Post-Doctoral Fellow in Chemistry of materials

Synthesis and characterization of dual emitters nanocrystals

Semiconductor colloidal nanocrystals present optical properties tunable with their size and compositions, and it’s been 8 years that these nanocrystals are introduced in displays as a source of light. In these displays a blue LED excites a mixture of green and red emitters such as the combination of these three colors provide a large range of color. This range is as broad as the emission of nanocrystals is narrow and at the right wavelength. Among existing colloidal nanocystals, 2D nanoparticles (called nanoplatelets NPLs),¹ present enhanced optical properties due to their thickness control at the atomic scale without roughness. In a dispersion, all the NPLs have exactly the same thickness and present a narrow emission around kT.² The goal of the project will be to propose a new generation of dual emitters NPLs.

During the Post-doc, the student will have to synthesize and study heterostructured NPLs with dual green and red emission with high quantum efficiency, the final goal being their integration in LEDs. We recently showed that CdSe/CdTe/CdSe NPLs emit both narrow green and broad red emission and that the ratio between the two colors can be tuned by the fluence.³ The next challenge is to increase the quantum efficiency through the growth of a shell of semiconductor. Thus, first it will be necessary to blue shift the optical properties of dual emitters NPLs in order to preserve emission on the right wavelengths after the growth of the shell. Here we propose to either work with thinner NPLs, or alloyed NPLs or NPLs with steps.

References

¹ Ithurria, S. et al. Quasi 2D Colloidal CdSe Platelets with Thicknesses Controlled at the Atomic Level. J. Am. Chem. Soc. 2008, 130 (49), 16504–16505.

² Diroll, B. T et al. 2D II-VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration. Chem. Rev. 2023

³ Dabard, C. et al.Double-crowned 2D semiconductor nanoplatelets with bicolor power-tunable emission Nature Comm. 2022, 13 (1), 5094