Controlled size of PbS nanocrystals doped ORMOSIL

PbS semiconductor nanocrystals were grown inside an organically modified silicate (ORMOSIL) matrix prepared by the sol–gel method assisted by high power ultrasounds. Surface capping agent was used to control the growth and aggregation of PbS nanocrystals. The SANS intensity exhibits a crossover at 0.1 nm ⁻¹ . Data analysis using a two-correlation function indicates a medium-range structure built by PbS nanocrystals (6.5 nm mean crystal diameter) as observed by Transmission electron microscopy. A short-range structure accounts for a fine porosity (1 nm mean pore diameter) of the ORMOSIL matrix in agreement with gas isotherm. Band gap blue-shift confirms the exciton quantum confinement inside the PbS nanocrystals.