Optical properties and fluorescence of quantum dots CdSe/ZnS-PMMA composite films with interface modifications

Abstract

Processing and characterization of polymer nanocomposites based on poly (methyl methacrylate) (PMMA) matrix with embedded core-shell CdSe/ZnS quantum dots (QD's) were presented in this work. The aim is to preserve the optical activity of QD's in nanocomposite processing with improved mechanical properties. The modification of QD's CdSe/ZnS-PMMA interface was achieved with 3-mercaptopropyltrimethoxysilane (MPTMS). Nanocomposites were processed by solution casting. The samples of pure PMMA, and composites with unmodified and silane modified QD's CdSe/ZnS were processed. FTIR analysis revealed modification of QD's with silane and characteristic bonding with PMMA matrix. Raman spectrum confirms a presence of alloyed layer at the core-shell interface. Time-resolved laser induced fluorescence measurements confirmed slight blue shift in QD's CdSe/ZnS-PMMA composite without interface modification, while there was a slight red shift with modified particles. Oxidation effects in quantum dots were removed with the use of PMMA as a host, and the core remained active, which was confirmed with FTIR analysis and time-resolved laser induced fluorescence measurements.