Structural studies of thin films of semiconducting nanoparticles in polymer matrices

We deposited thin layers of CdS and ZnS nanoparticles embedded in a thermoplastic cyclo-olephin copolymer (COC) with elevated optical transparency and highly bio-compatible. The nanoparticles were obtained by thiolate precursors previously dispersed in the polymer upon thermal treatment at temperatures ranging between 200 and 300 Celsius degrees depending on the desired size. The precursor/polymer solutions were spin coated in order to get thin films. The samples were mainly characterised by X-ray reflectivity (XRR) and by High Resolution Transmission Electron Microscopy (HRTEM) analyses. The HRTEM measurements showed that the nanoparticles have quasi-spherical shape without evident microstructural defects. The size of the nanoparticles depends on the annealing temperature, e.g. at 232 Celsius degrees the size of the CdS nanoparticles is about 4-5 nm.