The integration of inorganic photonic nanostructures with organic materials opens new possibilities to dynamically modify the optical response of photonic devices. This thesis focuses on how to generate efficient reflective structural colors and tune them in combination with a conducting polymer (CP). The main technological interest lies in color reflective displays, devices with ultralow power consumption that work with reflected environmental light. The main challenge is to obtain dynamic color tunability while maintaining good chromaticity and brightness. We first studied how to make efficient reflective structural colors and focused on highly reflective optical nanocavities based on metal-insulator-metal (MIM), combining the Fabry-Pérot effect and a broadband absorber. We demonstrated a full color palette by changing the spacer thickness and proposed different configurations to improve the chromaticity and reproduce black. We also explored subtractive coloration with a cyan-yellow-magenta (CYM) system to increase the relative luminance for reflective displays. We covered the CYM spectrum by combining plasmonic nanodisks with optical nanocavities, using a scalable nanofabrication method based on colloidal lithography. Subsequently, we modified our optical nanocavities by replacing the dielectric spacer with a low bandgap electroactive CP, polythieno[3,4 b]thiophene(pT34bT), to obtain active color tunability. By integrating the optical nanocavities in an electrochemical cell, we proved tunability of the reflected color across all the visible spectrum with low operating voltages and similar reflectance values for all the oxidation states. Those cavities can be considered a proof of principle for the development of tunable monopixels.  In addition, we explored vapour phase polymerization (VPP) as an alternative deposition method with direct patterning possibilities by UV-exposure of the precursor oxidant film. We developed optical reflective nanocavities with a spacer based on poly[3,4-ethylenedioxythiophene]:Tosylate (PEDOT:Tos) on metal mirrors, generating color images by different UV exposures. We showed the feasibility of generating images by using a UV photomask with different contrasts. Those cavities could also be switched in color by electrochemical tuning in an electrolyte, reaching different electrochromic states. This method has the potential to be extended to other types of polymers and to be used for display technologies.

Plasmonic metasurfaces for color generation are emerging as important components for next generation display devices. Fabricating bright plasmonic colors economically and via easily scalable methods, however, remains difficult. Here, the authors demonstrate an efficient and scalable strategy based on colloidal lithography to fabricate silver-based reflective metal-insulator-nanodisk plasmonic cavities that provide a cyan-magenta-yellow (CMY) color palette with high relative luminance. With the same basic structure, they exploit different mechanisms to efficiently produce a complete subtractive color palette. Finite-difference time-domain simulations reveal that these mechanisms include gap surface plasmon modes for thin insulators and hybridized modes between disk plasmons and Fabry-Perot modes for thicker systems. To produce yellow hues, they take advantage of higher-energy gap surface plasmon modes to allow resonance dips in the blue spectral region for comparably large nanodisks, thereby circumventing difficult fabrication of nanodisks less than 80 nm. It is anticipated that incorporation of these strategies can reduce fabrication constraints, produce bright saturated colors, and expedite large-scale production.

Plasmonic metasurfaces based on ensembles of distributed metallic nanostructures can absorb, scatter, and in other ways shape light at the nanoscale. Forming hybrid plasmonic metasurfaces by combination with other materials opens up for new research directions and novel applications. This perspective highlights some of the recent advancements in this vibrant research field. Particular emphasis is put on hybrid plasmonic metasurfaces comprising organic materials and on concepts related to switchable surfaces, light-to-heat conversion, and hybridized light-matter states based on strong coupling.

Precise manipulation of light-matter interaction has enabled a wide variety of approaches to create bright and vivid structural colours. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches significantly impede their further development towards flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Herein, we present a simple and efficient method to generate structural colours based on nanoscale conducting polymer films prepared on metallic surfaces via vapour phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable colours from violet to red. Together with greyscale photomasks this enables fabrication of high-resolution colour images using single exposure steps. We further demonstrate spatiotemporal tuning of the structurally coloured surfaces and images via electrochemical modulation of the polymer redox state. The simple structure, facile fabrication, wide colour gamut, and dynamic colour tuning make this concept competitive for future multi-functional and smart displays.