Green synthesis of anisotropic CdSe nanocrystals via a non-phosphine based method

- Green synthesis of anisotropic CdSe NCs was reported via a phosphine free method.
- All the synthesised CdSe NCs exhibit good optical properties with high quantum yield.
- Emission spectra displayed three different growth modes.
- Anisotropic growth is attributed to both oriented attachment and Ostwald ripening.

We herein report the synthesis of highly luminescent anisotropic CdSe nanocrystals (NPs) via a non-trioctylphosphine (TOP) based method in an open air. The synthesis involved the reaction between oleic acid cadmium oxide complex as cadmium precursor and selenium precursor produced via in situ dehydrogenation of paraffin liquid by selenium powder. By varying the reaction time, the temporal evolutions of the optical and structural properties of the as-synthesised CdSe nanocrystals (NCs) were investigated. Optical analyses show that all the as-synthesised CdSe NCs possess good optical properties and emit in the green region with band edge luminescence, defined excitonic peaks, narrow emission width and high quantum yield (QY). The electron microscopy micrographs shows that small, spherical and monodispersed particles are produced at the beginning of the reaction while mixtures of isotropic and anisotropic structures (prism, rod and hexagonal) are produced as the reaction progressed. The Fourier transform infrared spectroscopy (FTIR) analysis confirmed the effective capping of oleic acid.

340