Preparation, Surface Modification And Applications Of Lanthanide-doped Upconversion Nanoparticles

Lanthanide-doped upconversion nanoparticles have many advantages in practical applications,such as high chemical stability, sharp emission bandwidths, large anti-Stokes shifts and highresistance to photobleaching. Triplet-triplet annihilation (TTA) based energy upconversion exhibitsmany merits, including low excitation power density, tunable excitation and emission wavelengthsimply by independent selection of the sensitizer and the acceptor during the upconversion process.In this thesis, we focus on the preparation, surface modification and applications oflanthanide-doped upconversion nanoparticles. The main contents can be divided into four parts.1. The preparation and surface modification of lanthanide-doped upconversionnanoparticlesNaYF4: Yb/Er (20:2mol%)、NaYF4: Yb/Tm (20:0.5mol%)、NaYF4: Yb/Er, Tm (20:1.8:0.2mol%) upconversion nanoparticles were synthesized with solvo-thermal method. Theircorresponding morphology, crystalline, spectral were characterized and analyzed. NaYF4:Yb/Tm(20:0.5mol%)@NaYF4nanoparticles with core-shell performed more significantluminescence properties and silica-coated nanoparticles were prepared.2. The study on the energy transfer between the upconversion nanoparticles and organicsOrganic molecules spiropyran was combined with nanoparticles via covalent bond and thepolymer was connected with adsorption effect. The energy transfer between the nanoparticles andorganics was studied.3．The study on UCNP-TTA based dual upconversionSuitable upconversion nanoparticles and sensitizer, annihilator in the process of TTA wereselected for UCNP-TTA based dual upconversion. The luminescence of UCNP was absorbed by thesensitizer and TTA process was occurred. UCNP-TTA based dual upconversion was achieved insolution.