Up-conversion luminescence and near-infrared quantum cutting in Y _6O_5F_8:RE~(3+) (RE = Yb, Er, and Ho) with controllable morphologies by hydrothermal synthesis

摘要

Monodisperse and uniform Y_6O_5F_8:RE ~(3+) (RE = Yb, Er, and Ho) microarchitectures with various morphologies have been constructed by a facile surfactant-assisted hydrothermal route, and their up-conversion luminescence and NIR quantum cutting properties were investigated. Hollow hexagonal prisms, microbundle gatherings by rods, and solid hexagonal prisms were designed by employing CTAB, PVP, and EDTA as additives, respectively. Under 980 nm excitation, the Y_(5.34)O_5F _8:0.6Yb~(3+), 0.06Er~(3+) samples obtained using different additives exhibit similar emission spectra profiles with predominating peaks at 670 nm; the Y_(5.34)O_5F_8:0.6Yb ~(3+), 0.06Ho~(3+) samples give green emissions with the strongest peaks around 544 nm. The NIR quantum cutting for the Y _6O_5F_8:Yb~(3+), Ho~(3+) samples was identified by the NIR emission spectra upon both 360 and 450 nm excitation. The corresponding quantum cutting mechanisms were discussed through the energy level diagrams, in which a back-energy-transfer from Yb~(3+) to Ho ~(3+) was first proposed to interpret the spectral characteristics. A modified calculation equation for the quantum efficiency of Yb ~(3+)-Ho~(3+) coupled by exciting at 450 nm was suggested according to the quantum cutting mechanism. The efficient NIR luminescence and quantum cutting in Yb~(3+), Ho~(3+) co-doped Y_6O _5F_8 reveal a possible application in modifying the solar spectrum to enhance the efficiency of silicon solar cells.