Preparation and characterization of PbS quantum dots doped ormocers

A new method for the preparation of semiconductor PbS quantum dot-doped Orm ocer (Organically Modified Ceramic) has been developed. The Ormocer matrix was prepared through the hydrolysis and condensation of alkoxysilane precur sors (sol-gel process). Formation of PbS particles took place in the porous Ormocer through H2S gas reaction with a lead precursor incorporated at the solution stage. Control of the PbS dot size was achieved through the use o f organically substituted trifunctional silanes. Particle formation and gro wth was studied under different experimental conditions (e.g. temperature a nd lead precursor concentrations) where nucleation and aggregation processe s occurred. Determination of the average particle size was done by XRD. Tra nsmission electron microscopy was also used to determine particle diameter as well as particle size distribution. Optical absorption spectra were meas ured at the UV-VIS wavelength range. Absorption edge blue shifts showed the quantum confinement effect in these materials. The non-hydrolyzed groups b onded to the silane prevented uncontrolled nucleation and aggregation durin g the particle formation and growth, i.e. at the solution stage by the homo geneous distribution of the Pb salts or at the xerogel state by the capping of the growing particles.