Structural and photoluminescent investigation of LTbH/LEuH nanosheets and their color-tunable colloidal hybrids

Abstract

Rare-earth phosphors with tunable optical properties are used in display panels and fluorescent lamps and have potential applications in lasers and bioimaging. This work reported the preparation, structure and photoluminescence of the unilamellar nanosheets containing Tb³⁺/Eu³⁺ delaminated from layered rare-earth hydroxides (LRHs). Highly crystallized LTbH and LEuH with monolayered dodecyl sulfate ions vertical to the layer were synthesized by a one-step homogeneous precipitation method for the first time, and were shown to be readily delaminated in formamide. The obtained unilamellar nanosheets exhibited a decrease of the coordination number of the lanthanide ions, to probably 8-fold, when compared with the bulky precursor crystals. This change resulted in different photoluminescence emission peak shapes. Colloidal hybrids were constructed using these nanosheets as building blocks, and the emission colors of the hybrids can be facilely and precisely tuned from green to yellow, orange, and finally to red by controlling the relative contents of the two kinds of nanosheets. This method provides a novel and simple route to prepare color-tunable hybrid materials from 2-dimensional crystals.