One-pot synthesis of metallic nanoparticles, conducting polymer and luminescent materials for potential optical device applications

Abstract

This study explores the morphological and optical properties of luminescent nanocomposites synthesized via a one-pot route, integrating gold nanoparticles (AuNPs), the Eu3+ complex [Eu(tta)3(H2O)2], where tta = thenoyltrifluoroacetone, and polypyrrole (PPy), enabling simultaneous polymerization and nanoparticle nucleation in a single reaction medium. By varying the concentrations of pyrrole monomer (Py), chloroauric acid (HAuCl₄), and the Eu3+ complex, we obtained luminescent hybrid materials, where the conducting polymer acts as a structural matrix for nanoparticle growth, a colloidal stabilizer, and a stabilizing matrix that preserves the europium complex's luminescence quenching. Structural characterization revealed crystalline AuNPs in the face-centered cubic phase, with an average size of 8.5 nm (XRD), and Raman spectra exhibited characteristic peaks corresponding to polypyrrole. Complementary confocal microscopy images revealed dual emission from Eu3⁺ and PPy, and AFM demonstrated increased surface roughness in composites, confirming the successful formation of polymer-encapsulated AuNPs. Data also confirmed by TEM images, showing gold nanoparticles coated with the conducting polymer PPy. Optical studies identified the plasmonic band of AuNPs (~ 450 nm), ligand-centered absorption (~ 375 nm), and PPy absorption (~ 250 nm) via UV–Vis spectroscopy. Emission spectra highlighted enhanced Eu3⁺ intra-configurational transitions (5D0 → ⁷F0-4) in systems with lower-to-medium PPy content and higher HAuCl₄/[Eu(tta)₃(H₂O)₂] ratios, suggesting Metal-Enhanced Fluorescence (MEF). The results indicate that the hybrid nanocomposite can enhance optoelectronic sensing by enabling plasmon-based sensing with gold and monitoring through the intensity profile and variation of intra-configurational transition wavelengths. This study highlights the potential for improved optoelectronic devices through the synergistic properties of the nanocomposites. ∙ Luminescent hybrid materials were successfully synthesized via a one-pot route, combining gold nanoparticles (AuNPs), polypyrrole (PPy) and europium luminescent complex. ∙ PPy acts as a structural matrix and colloidal stabilizer, controlling nanoparticle growth and dispersion and providing a stabilizing framework that preserves the luminescence quenching of the europium complex. ∙ Under optimized experimental conditions, the Metal-Enhanced Fluorescence (MEF) leads to improved optoelectronic properties of the luminescent hybrid materials.