Phosphine-free synthesis of Ag-In-Se alloy nanocrystals with visible emissions.
As promising heavy metal-free emitting materials, Ag-In-Se nanocrystals (NCs) are conventionally synthesized using organic phosphine agents and exhibit near-infrared emissions. In this work, we demonstrate a rapid phosphine-free approach for synthesizing Ag-In-Se alloy NCs with the emissions tunable to the visible region on the basis of the phosphine-free dissolution of Se powder. At room temperature, Se powder is reduced by dodecanethiol and dissolved in oleylamine to produce a Se precursor. The resultant Se precursor is highly active, which permits rapid synthesis at a relatively low temperature, such as at 90 °C for 150 s. By optimizing the size, structure, and composition, the photoluminescence quantum yield of the as-synthesized Ag-In-Se NCs is enhanced to up to 10%. The growth of the Ag-In-Se NCs involves composition and phase transition, which strongly depend on the reaction temperature. The Ag2Se nuclei form first, and the Ag-In-Se NCs are produced by doping In(3+) into the preformed Ag2Se nuclei. Tetragonal phase Ag-In-Se is obtained below 170 °C, while the orthorhombic phase appears over 190 °C. The potential of Ag-In-Se NCs as red emitting phosphors for lighting-emitting diodes is further demonstrated.
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China. hao_zhang@jlu.edu.cn.
Dong
D
Yao
Huiwen
H
Liu
Yi
Y
Liu
Chunwei
C
Dong
Kai
K
Zhang
Yu
Y
Sheng
Jianli
J
Cui
Hao
H
Zhang
Bai
B
Yang