Resonant cavity phosphor.

While phosphors play an immensely important role in solid-state lighting and full-colour displays, it has been noted lately that their performance can be largely improved via structural engineering. Here, phosphor material is synergistically merged with yet another structurally engineered platform, resonant cavity (RC). When a 40-nm-thick colloidal quantum dot (CQD) film is embedded in a tailored RC with a moderate cavity quality factor (Q ≈ 90), it gains the ability to absorb the majority (87%) of excitation photons, resulting in significantly enhanced CQD fluorescence (29×) across a reasonably broad linewidth (13 nm). The colour gamut covered by red and green pixels implemented using the RC phosphor-along with a broad bandwidth (20 nm) blue excitation source-exceeds that of the sRGB standard (~121%). The simple planar geometry facilitates design and implementation of the RC phosphor, making it promising for use in real applications.