Ag-CdS@SiO2 platforms: Electromagnetic field enhancement systems for optical sensing

MARTINEZ RICCI, MARIA LUZ; ONNA, DIEGO; BILMES, SARA A.; MISSONI, LEANDRO L.; FERNANDEZ CASAFUZ, AGUSTINA; PEREZ IPIÑA, IGNACIO

Congreso; XIX Brazilian MRS Meeting; 2021

Nanocomposites are nowadays one of the most promising architectures for the production of highly tunable systems. Adjusting the composite scale with optical wavelengths gives the possibility to confine and enhance the electromagnetic (EM) density field inside the structures. The localized density fields generated convert these nanocomposites as suitable platforms for diverse applications such as optical sensing.In particular, mesoporous thin films (MTFs) are adequate platforms for optical applications since mesoporous oxides such as SiO2, TiO2 or Al2O3 are highly reproducible, homogeneous and transparent, which makes them ideal for photonic or plasmonic platforms. In addition to these characteristics, the possibility to use the mesoporosity given by pores or channels as nanoreactors allows housing nanoparticles (NPs) in the nanostructure giving rise to the design of composite hierarchical systems.In this talk, we will present SiO2 MTFs with fluorescent CdS nanoparticle inclusions. We will show that photoluminescence (PL) signal is increased in strategic combination with Ag nanoparticles due to EM field enhancement. For this aim, we will present how to adequately immobilize semiconductor (SC) NPs in nanopores to obtain a good and reproducible PL signal. In these composites, SC particle size is a fundamental parameter being difficult to determine when SC NPs are included in complex structures. We will introduce DdD method, a nondestructive, cheap and in situ procedure based on the deconvolution of the absorbance spectrum to determine the PSD distribution of SC NPs inside complex structures. Finally, we will show that the strategic adding of Ag NPs to this structure allows an intensification of the PL signal. Electromagnetic modeling was applied to understand the role of each parameter of the structure and understand the role of the different parameters in the final optical response.