One-pot synthesis of CdSe nanoparticles exhibiting quantum size effect within a sol-gel derived ureasilicate matrix

This paper describes the one-pot synthesis of CdSe nanoparticles (NPs) exhibiting quantum size effect, by the reaction between cadmium and selenosulfate ions in the presence of 3-mercaptopropyltri-methoxysilane (MPTMS), within a hybrid organic-inorganic xerogel material produced by sol-gel. The highly transparent, homogeneous and flexible xerogel matrix doped with the CdSe NPs was prepared using an organically modified silicon alkoxide (3-isocyanatepropyltriethoxysilane) and a di-amine functionalized poly(ethylene oxide)/poly(propylene oxide) (jeffamine ED-600), as precursors, which by subsequent hydrolysis and condensation reaction formed a solid network. The influence of the molar ratio between cadmium and selenosulfate ions and between cadmium ion and MPTMS in the optical properties of the nanocomposites was investigated. The materials were characterized by absorption, steady-state and time-resolved photoluminescence (PL) spectroscopy and by TEM. The absorption spectrum showed the presence of CdSe NPs with quantum size effect. The PL studies showed the presence of CdSe NPs with near band-edge emission. The developed method allows in a simple manner, at ambient temperature, using inexpensive reagents and without the need of the previous synthesis of the NPs by colloidal methods, the production of hybrid materials doped with semiconductor NPs showing quantum size effect. The developed sol-gel process allows also the control of the optical properties of the obtained CdSe NPs embedded within the network by adjusting the molar ratio between cadmium ion and MPTMS and between cadmium and selenium ions. The presence of NPs with near band-edge emission stabilized within a solid matrix opens the perspective of practical applications that take advantage of the optical properties of NPs, in particular photophysical applications such as photoluminescent devices. (C) 2014 Elsevier B.V. All rights reserved.