CdS Nanoparticles in Gel Film Network: Synthesis, Stability and Optical Properties

Abstract

Development of quantum (Q) size metal and semiconductor nanoparticles^1–3 in various kinds of hosts and their optical and opto-electronic characterization have become an important area of research in recent times. The importance of this activity is derived from the possibility of application of such materials in photonics. Sol-gel processing has proved to be a very useful method for generating these new composites, and a large number of papers have been published ^4–6 in the last few years. Much of this work deals with generation of sulphide semiconductor nanoparticles in monolithic silica or silicate bodies. In general the basic optical properties of such materials are characterized by an excitonic HOMO-LUMO transition at around 400–460 nm and a fluorescence band around 460 nm, both at 298 K. The transition depends on the size of the microcrystals confined in a suitable host. At the lowest excitonic state ⁷ the CdS particles should exhibit an absorption shoulder in the UV range (270 – 300 nm). This has also been observed experimentally.^8–10