Confined nucleation and growth of organic nanocrystals in sol–gel matrices

Abstract

We have engineered new hybrid organic-inorganic materials through a simple and generic preparation of stable organic nanocrystals grown in gel-glass matrices. This process was based on confined nucleation and growth of dyes in the pores of dense gels. For bulk samples, narrow size distributions of particles were obtained between 10 and 20 nm in diameter. We extended this method to the preparation of organic nanocrystals embedded in sol-gel thin films by spin-coating. For all these nanocomposite samples, we significantly increased the dye stability and obtained promising optical properties (luminescence, NLO properties, SHG). Moreover we also demonstrated the basic working principles of a new type of fluorescent nanosensors through the preparation of organic luminescent nanocrystals grown in silicate films.

Electrodeposition of Inorganic/Organic Hybrid Thin Films

“…[32,33] There are also ways to obtain hybrid materials by introducing one of the components to another by post treatments. [34][35][36] Guest materials are loaded into pre-established porous host materials. An especially beautiful example of such an approach is the ordered loading of functional molecules into straight channels of zeolites, as studied by Calzaferri and co-workers, which is nicely summarized in their review.…”

“…[36] The purpose for synthesizing hybrid materials varies from enhanced bioactivities, [26][27][28] charge storage, [31] and magnetic properties, [33] to luminescence and nonlinear optical properties. [28,30,34] One of the most successful industrial applications of the special properties exhibited only by the combination of inorganic and organic materials is that of photography. [37][38][39] The sensitivity of photographic films is greatly enhanced by strongly lightabsorbing dye molecules attached to particles of silver halides, which are poorly sensitive to visible light.…”

Optical Properties of Hybrid Organic‐Inorganic Materials and their Applications

“…A. Ibanez and co-workers advantageously developed this approach in particular for third order nonlinearities. [307][308][309][310] However, the poling process is reported to be hard to achieve due to the ionic conductivity at high temperature and also disorientation during the cooling down. [310] On the other hand, the use of noncentrosymmetric crystal organization can be a way to achieve strong SHG at the molecular level.…”

“…[271] An original strategy adopted in order to increase the concentration of nonlinear active species was to grow nanocrystals of dyes in inorganic glasses. [307][308][309][310] Stilbene 3 nanocrystals were grown in sol-gel glasses. [344] The final composite materials showed strong nonlinear absorption at visible wavelengths.…”

Direct Condensation Method for the Preparation of Organic‐Nanoparticle Dispersions

“…Several variants of this method were developed, including, the use of ultrasound [11] or precipitation in sol-gel matrices. [12,13] Due to the fact that in the reprecipitation process a solution of organic material (of typically about millimolar concentration) is added to a large excess (about 100-fold) of non-solvent, only very dilute particle dispersions can be obtained. That is one main disadvantage of this fast and simple method.…”