| abstract |
Disclosed is a method for enhancing upconversion luminescence of rare-earth doped particles comprising a host material, an enriched concentration of activator (emitter) and a sufficient concentration level of sensitiser, the method comprising subjecting the particles to increased irradiance. The increased irradiance is higher than presently used relatively low irradiance levels. Enhancing upconversion luminescence involves enhancing luminescence intensity, brightness and/or upconversion efficiency. Particles are preferably subjected to an irradiance power density sufficient to overcome or reverse concentration quenching. The activator preferably has an intermediate meta stable energy level which accepts resonance energy from the sensitiser excited state level. In another form, particles are designed to minimize or exclude quenchers from the upconversion system between sensitizer and activator, such as the core-shell particles wherein the core comprises the host material, sensitiser and the activator, and the shell comprises a material which prevents, retards or inhibits surface quenching. |