Patterned structures of in situ size controlled CdS nanocrystals in a polymer matrix underUV irradiation

Abstract

A method of in situ formation of patterns of size controlled CdS nanocrystals in a polymermatrix by pulsed UV irradiation is presented. The films consist of Cd thiolate precursorswith different carbon chain lengths embedded in TOPAS polymer matrices. Under UVirradiation the precursors are photolyzed, driving to the formation of CdS nanocrystals inthe quantum size regime, with size and concentration defined by the number of incidentUV pulses, while the host polymer remains macroscopically/microscopically unaffected.The emission of the formed nanocomposite materials strongly depends on thedimensions of the CdS nanocrystals, thus, their growth at the different phases of theirradiation is monitored using spatially resolved photoluminescence by meansof a confocal microscope. X-ray diffraction measurements verified the existenceof the CdS nanocrystals, and defined their crystal structure for all the studiedcases. The results are reinforced by transmission electron microscopy. It is provedthat the selection of the precursor determines the efficiency of the procedure,and the quality of the formed nanocrystals. Moreover it is demonstrated thatthere is the possibility of laser induced formation of well-defined patterns of CdSnanocrystals, opening up new perspectives in the development of nanodevices.