Tunable dual color emission from the opposite faces of silicon nanoparticle embedded gel-glass.

A luminescent silicon nanoparticle embedded gel-glass, prepared by room temperature hydrolysis and reduction of aminosilane, exhibits intriguing dual photoluminescence (PL) from opposite faces of the glass. The face, which is excited with UV, exhibits excitation energy dependent blue-green emission. As the excitation energy is varied from 350 nm to 450 nm the PL peaks shift from 435 nm to 506 nm. The opposite surface, on the other hand emits nearly excitation independent green light – the PL peak shifts by ∼17 nm as the excitation energy is varied from 350 nm to 450 nm. The luminescent properties provide interesting insights into the light emission mechanism from nanostructured silicon. Spectral filtering by reabsorption and photon reabsorption-reemission in a size distributed nanoparticle system having different optical gaps play a combined role in the observed dual emission. We show that the dual emission can be tuned by simply varying the thickness of the glass. Such dual emission renders the luminescent glass amenable for several applications as a novel solid state display material. [Display omitted] • A silicon nanocrystal embedded luminescent gel-glass exhibits intriguing dual photoluminescence. • The gel-glass emits different wavelengths from different faces for the same excitation energy. • Dual emission is explained by successive photon reabsorption-reemission and spectral filtering. [ABSTRACT FROM AUTHOR]