“We can make a red sub-pixel go to blue, for instance,” said researcher Debashis Chanda. “In other displays that is not possible because they need three static colour filters to show the full RGB colour. We don’t need that now; a single sub-pixel-less pixel can be tuned across a given colour gamut.”
This effect is plasmonic, with surface morphology-induced, polarisation-dependent plasmonic resonance and a combination of interfacial and bulk liquid crystal effects.
Each phenomenon affects colour , with bulk liquid crystal reorientation leading to polarisation rotation at low voltage, and surface liquid crystal reorientation leading to plasmonic resonance shifting at higher voltages.
It works with white ambient light, which passes through a polariser, substrate and high-birefringence liquid crystal layer to interact with a nano-structured aluminium layer. The wavelength of absorption depends on the liquid crystal orientation near the surface and the polarization of incident light.
The applied voltage creates an electric field which changes the orientation of the bulk liquid crystal and interfacial liquid crystal.
As far as the researchers can determine from the un-optimised proof-of-concept device, switching speed will be fast enough for “standard display frame rates”.
The full story is available in Nature Communications as ‘Actively addressed single pixel full-colour plasmonic display‘, from which some of this article is taken.
Image: University of Central Florida researchers Debashis Chanda and Daniel Franklin have use plasmonics to make a single pixel tuneable red-green-blue structure.