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Anthony Choi and his team at the University of Hong Kong hasdeveloped a smart coating of green and orange-red fluorescentnanospheres, which emits white light when applied to blue(470 nm) LEDs. The dye-loaded polystyrene particlesself-assemble into an opal-like photonic structure that helps tochannel more light out of the solid-state devices and provides asmooth emission profile (Nanotechnology 19355203).

Typically, chip makers obtain white light by coating blue LEDs witha phosphor layer or by optically mixing red (R), green (G) and blue(B) emitters. The RGB approach is more efficient in terms of lightoutput, but combining the light in the right proportions to avoidcolour separation can present a challenge. Conversely, thephosphorous coating is much easier to use, but gives a reducedlight output due to the energy losses incurred during spectral downconversion.