Synthesis of CdSe quantum dot ZnS matrix thin films via electrospray organometallic chemical vapor deposition

A modified organometallic chemical vapor deposition technique is used to incorporate luminescing II-VI nanocrystals (NCs) into ZnS thin films. The NCs are synthesized in organic solution and consist of a CdSe core and ZnS shell. The ZnS matrix is deposited by OMCVD from diethyl zinc and hydrogen sulfide while the NCs are delivered to the film surface via electrospray. Varying the size of the CdSe NC core enables tunable emission from the blue to the red. The ZnS shell provides electronic and chemical passivation of the CdSe core improving its luminescence and thermal stability. The thin films exhibit room temperature photoluminescence (PL) and cathodoluminescence (CL) dominated by emission from the NCs. PL quantum efficiencies greater than 10% have been achieved. The dependence of thin film luminescence and microstructure on deposition temperature is studied using optical photoluminescence and X-ray diffraction. Particular emphasis is placed on the relationship between the host ZnS structure and the optical properties of the NC-ZnS composite thin film. (C) 1998 Elsevier Science B.V. All rights reserved.