Reviving near infra‐red emission of Ag₂S nanoparticles using interfacial defects in the Ag₂S@CdS core–shell structure

Abstract

Ag 2 S@CdS core-shell particles were synthesized with different Cd source content as a measure of shell thickness using a pulsed microwave irradiation method. The particles were verified structurally using X-ray diffraction, energy dispersive X-ray analysis and transmission electron microscopy. Optical spectroscopy revealed that core-shells show an absorption peak at 750 nm and an emission peak located around 800 nm after 6 min of microwave irradiation. With continued microwave treatment, the NIR luminescence first vanished but it was revived after 12 min of irradiation, which was 100 nm red shifted. This new type of NIR emission in Ag 2 S with sizes greater than 5 nm is due to the proximity of a highly deficient CdS shell with strong red emission that was stable for more than 6 months in water. A mechanism has been suggested for this type of emission.

Квантовый выход люминесценции и константы рекомбинации в коллоидных core/shell квантовых точках Ag-=SUB=-2-=/SUB=-S/AnS и Ag-=SUB=-2-=/SUB=-S/SiO-=SUB=-2-=/SUB=-

“…Поскольку рекомбинационная люминесценция КТ Ag 2 S имеет интерфейсную природу [20,21], формирование структур ядро/оболочка на их основе является эффективным способом повышения QY. Известны попытки формирования различных структур ядро/оболочка, таких как Ag 2 S/ZnS [25][26][27], Ag 2 S/CdS [28], Ag 2 S/SiO 2 [11], Ag 2 S/Ag 2 W O 4 [29], Ag2S/SnS2 [30]. Отмечается, что формирование оболочки приводит к росту QY люминесценции.…”