Synthesis of monodisperse cadmium phosphide nanoparticles using ex-situ produced phosphine.

The synthesis of nanoparticles using a gas-liquid interfacial reaction, which for the first time is shown to result in highly monodisperse materials across a range of sizes, is presented. We demonstrate, using cadmium phosphide as the paradigm that this synthesis method can provide colloidal nanocrystals or quantum dots monodisperse enough so that for the first time multiple transitions in their absorbance spectra can be observed. Clear evidence is given that the resulting cadmium material is Cd(6)P(7) and not Cd(3)P(2), and a thorough investigation into the role of temperature and growth time and their effects on the optical properties has been conducted. This strategy can be extended to synthesize other relevant members of the binary component pnictide semiconducting family, and the chemistry of the pnictide compound formation using this synthetic methodology has been explained using the redox potential of the metals. The suitability of the resulting cadmium phosphide quantum dots for applications in light-emitting diodes (LEDs) has further been demonstrated.