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.