Eu Sensitization via Nonradiative Interparticle Energy Transfer Using Inorganic Nanoparticles.

Phosphors have been used successfully for both research and commercial applications for decades. Eu-doped materials are especially promising, because of their extremely stable, efficient, and narrow red emission lines. Although these emission properties are ideal for lighting applications, weak absorption in the blue spectral range has until now prevented the use of Eu-based phosphors in applications based on blue light-emitting diodes. Here, we demonstrate a sensitization mechanism of Eu based on interparticle Förster resonance energy transfer (IFRET) between lanthanide-doped inorganic nanocrystals (NCs). Compared to co-doping different lanthanides in the same host crystal, IFRET allows an independent choice of host lattices for Eu and its sensitizer while potentially greatly reducing metal-to-metal charge transfer quenching. We demonstrate IFRET between NCs, resulting in red Eu emission upon blue excitation at 485 nm using LaPO:Tb/LaPO:Eu and LaPO:Tb/YVPO:Eu NC mixtures. These findings pave the way toward engineering blue-sensitized line emitters for solid-state lighting applications.