The self-assembly of nanocrystals into ordered hierarchical structures offers a powerful way to engineer emergent optical properties. In this study, we demonstrate a straightforward, bottom-up co-assembly of cerium oxide (CeO 2 ) and gold (Au) nanocrystals (NCs) into binary arrangements that enhance fluorescence via plasmon-exciton coupling. By systematically varying the Au-NCs concentration, we identify an optimal doping level at 1.6 mol% Au where the emergence of ordered domains with Frank-Kasper structural motifs coincides with a 15-fold enhancement in fluorescence emission measured relative to the baseline integrated emission of the disordered CeO 2 -NCs aggregates. This amplification is driven by the creation of intense near-field electromagnetic hotspots from the Au-NCs’ localised surface plasmon resonance (LSPR), whose effect is maximised within this specific, locally ordered architecture. Conversely, excessive doping (3.0 mol% Au) results in a loss of optical performance due to phase segregation and disruption of this critical ordering. This work establishes a direct correlation between the NCs concentration, the spontaneous formation of complex ordered domains, and the resulting collective optical properties, demonstrating a simple yet effective pathway for creating tunable nanophotonic materials. • A simple bottom-up route to create tunable nanophotonic materials • 500% fluorescence boost at 1.6 mol% Au via ordered nanocrystal domains • Plasmon-exciton coupling is optimised in Frank-Kasper architectures • Structural order drives plasmonic enhancement; disorder reduces effect • Direct link shown between dopant level, structural order, and optical output

The development of smart materials that can react to external stimuli and provide controlled and frequently reversible responses is facilitated by the coupling of physical effects. In this work, a photo-pyroelectric effect based on a piezoelectric polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) polymer composite with fullerene C 60 incorporated at different concentrations (1, 3, 5, 10 and 20% wt.) has been developed with the aim of obtaining a multi responsive material: together with the piezoelectric and pyroelectric characteristics of the polymer, the inclusion of the fillers allow a photo-pyroelectric response, suitable for optoelectronic applications. The addition of fullerene – C 60 leads to a mechanical plasticizing effect in the polymer matrix, revealed by the decrease of the Young’s Modulus from 335 MPa to 157 MPa and an increase in the dielectric constant from approximately 10 to 20 at 100 Hz, for P(VDF-TrFE) samples with 20% wt. of fullerene – C 60 . A pyroelectric coefficient of 20 μC/m 2 ·K was achieved with a 10% wt. fullerene – C 60 loading, while maintaining a piezoelectric response of 15 pC/N. Further, under laser irradiation and due to the photo-pyroelectric response, the composite with 10% wt. fullerene – C 60 content reaches a generated voltage of 400 mV across a temperature variation of 1.4 °C, proving the multifunctionality of the materials and their applicability in applications including infrared detectors, thermometers, or energy harvesting, among others. A new photo-pyroelectric effect in a piezoelectric composite composed of Fullerene-C60 and the ferroelectric polymer P (VDF-TrFE) is presented. The material allows to directly produce an electric signal from light absorption through to this phenomenon, which offers a novel mechanism for optoelectronic energy conversion. Further, the material maintains its piezoelectric response, allowing for multifunctional mechano-electric, pyro-electric and photo-pyroelectric response. The photo-pyroelectric effect is enabled and improved by the polymer and fullerene's synergistic interaction, which is a crucial step in the development of high sensitive flexible photonic devices. • Photo-pyroelectric effect was demonstrated in piezoelectric and pyroelectric polymer composites of P(VDF-TrFE) with fullerene. • The influence of fullerene content on P(VDF-TrFE) was evaluated. • The mechanical, dielectric and piezoelectric properties are affected by the fullerene content. • A maximum pyroelectric coefficient of 20 μC/m 2 ·K was achieved with a 10% wt. fullerene – C60. • These composites are suitable for advanced applications with a generated voltage of 400 mV across a temperature variation of 1.4 °C.

This study reports ternary hybrid composites based on a poly(vinylidene fluoride) (PVDF) polymer matrix incorporating metal-organic framework (MOF) microparticles (HKUST-1), and an ionic liquid (IL) (bis(1-butyl-3-methylimidazolium) tetrachloronickelate ([Bmim] 2 [NiCl 4 ])), the pores of HKUST-1 being filled with the IL to tune the composite's electrical response. It is shown that introducing MOF and IL separately promotes nucleation of the electroactive phase of the polymer. However, the electroactive phase content of the PVDF/HKUST/IL composite lies between that of the MOF and IL composites. In IL-containing composites, the dielectric response is dominated by interfacial polarization and a conductivity-related peak, which mask the β -relaxation. The distribution of IL throughout the PVDF matrix and at the MOF-polymer interfaces causes the PVDF/HKUST/IL hybrid composite to display intermediate conductivity values between those of the PVDF/HKUST and PVDF/IL systems. While the IL dispersed within the PVDF matrix promotes ion transport and enhances conductivity, the IL located at the MOF-polymer interfaces may experience partial confinement or limited mobility. This dual-confinement effect allows for the precise "tuning" of conductivity and dielectric relaxation. The tailoring of electrical characteristics of these ternary composites provides a pathway for the development of electroactive materials suitable for a wide range of application requirements. • Synergetic effect of IL-laden MOF composites in a poly(vinylidene fluoride) polymer matrix is studied. • Polymer phase, thermal properties and dielectric relaxation spectra are evaluated for this nanocomposite. • The inclusion of these fillers affects the nucleation of crystalline phases • The IL filler is the main responsible by the conductivity behavior of the PVDF polymer. • The developed nanocomposite composites show suitable electrical properties for a variety of applications.