Triangular CdS Nanocrystals: Rational Solvothermal Synthesis and Optical Studies

A rational solvothermal route to fabricate triangular wurtzite CdS NCs, employing the reaction between Cd(Ac)2.2H2O and a new sulfur source, triphenylphosphine sulfide (TPPS) in toluene containing OAm as the capping surfactant. The triphenylphosphine (TPP) reacted with sulfur powder rapidly in toluene at room temperature to from TPPS, which will decompose under solvothermal conditional in the experiment. Based on the temperature-controlled wurtzite phase of the products and rational analysis of the preparatory experiments, a high TTPS concentration that provided higher chemical potentials and sufficient over saturation was utilized to fabricate triangular CdS NCs. The results observed indicate that high temperature is necessary, but a long growth time is not suitable for the synthesis of triangular CdS NCs. Also the synthesized triangles possess both band-edge and trap emissions, emitting visible red PL under UV light.