  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-P\'erot 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 with these approaches
significantly impede their further developments towards flexible, large-scale,
and switchable devices compatible with facile and cost-effective production.
Herein, we present a way to generate structural colours based on conducting
polymer thin films prepared on metallic surfaces via vapour phase
polymerization and ultraviolet (UV) light patterning. Varying the UV dose leads
to synergistic variation of film absorption and thickness, 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.
