Optical properties of free-standing gelatin-Si nanoparticle composite films and gelatin-Si-Au nanoparticle composite films

A free-standing fluorescent gelatin-Si nanoparticle composite thin film is facilely prepared by means of a filtration technique assisted by porous copper hydroxide nanostrands as a sacrificial layer. The as-prepared gelatin-Si nanoparticle composite film is greatly portable, flexible, transparent and freestanding. The most important advantage is its robust storage stability stored in ambient air, which make it promising for various applications. Meanwhile, a gelatin-Si-Au nanoparticle composite film is also successfully prepared by the formation of Au NPs in a gelatin-Si nanoparticle composite film through the in situ reduction of HAuCl4 at room temperature. The photoluminescence (PL) quenching and blue shift in the peak of the emission spectra occur due to the energy transfer from Si NPs to Au NPs. By varying the amount and size of Au NPs incorporated into the gelatin-Si nanoparticle composite film, the energy transfer efficiency can be controlled. This is a general method to prepare metal-semiconductor hybrid fluorescent nanomaterials, which offers the possibility of tuning the luminescence intensity and wavelength of the emitted light.