Full-color transparent display with red/green/blue-emitting lanthanide-doped nanoparticles heavily embedded in separated polyvinyl alcohol film
Luminescent transparent display technology is widely used in emerging fields such as augmented reality glass, head-up vehicle display, and commercial retail windows. While electroluminescent display is well established, the photoluminescent transparent screen of full-color rendering ability remains elusive due to the severe crosstalk between emitters. Herein, a full-color transparent screen of an orthogonal red/green/blue (R/G/B) luminescence is reported. Lanthanide fluoride nanocrystals are used as the emitters, where the color is tuned by a deliberate choice of doping activators including Tb3+, Eu3+, and Tm3+. Polyvinyl alcohol, with an identical refractive index to nanocrystals, is employed as the host matrix, enabling a high transparency up to 86% in the visible region upon a high loading content (~78 wt%) of nanocrystals. It should be noted that the nanocrystals are embedded in separate monolayers before integration by a UV-selective absorber, i.e., epoxy resin, which absorbs 254-nm UV to block cross-excitation between Tb3+ and Eu3+ layers, providing an asymmetric luminescent property from both sides of the screen. In a proof-of-concept experiment, a full-color prototype is showcased in real time for its potential applications in advanced displays of immersive experience.