Ma Qian,Yang Fanghong,Zhu Yuanna,Wang Junpeng,Che Quande,Shi Ruixia,Yang Ping
Red to near-infrared (NIR)-emitting ternary-alloyed CdTe
x
Se1−x
(x = 0–0.3) quantum dots (QDs) with tetrapod and dot morphologies have been synthesized by a facile method using oleic acid (OA) as single capping agent. The controlled
dot-shaped and tetrapod-shaped CdTe
x
Se1−x
QDs can be successfully obtained by adjusting the content of Te element. It is clear that CdTe
x
Se1−x
QDs display the tunable emission peaks from the visible light
(613.4 nm) to the NIR range (791.6 nm). With an inorganic CdZnS shell coated on the surface of CdTe0.1Se0.9 cores, the stability and PL efficiency of the resulting core/shell QDs can be improved dramatically, accompanied with the red-shift of emission peaks to longer
wavelength (795.6 nm). Peculiarly, a large blue shift of emission spectrum of CdTe0.3Se0.7/CdZnS core/shell QDs is observed, which is mainly ascribed to the shrink of the size of QDs by the fracture of tetrapod arms.
Ma Qian,Yue Hanxiao,Zhu Yuanna,Wang Junpeng,Che Quande,Shi Ruixia,Yang Ping
A series of red to near-infrared (NIR) emitting quantum dots (QDs) with spherical morphologies and tunable photoluminescence (PL) properties have been synthesized by a facile organic route using octadecene (ODE) as solvent and oleic acid (OA) as single capping agent. CdSe cores with
the average size of 4.5 nm display the typical optical behaviors with the PL emission peak around 610 nm. The coating CdZnS shells are introduced on the surface of CdSe cores for improving the photostability and PL efficiency of the initial QDs. As the thickness of CdZnS shells increasing,
the gradual red-shift of emission wavelength varying from 617 to 634 nm of the resulting QDs can be observed, along with the remarkable increase of PL quantum yield (QY). The composition-dependent CdTe
x
Se1-x
(CdTeSe) cores with the emission in NIR region
are easily carried out by adjusting the molar ratio of Se/Te. The abnormal variation of optical bowling effect is mainly ascribed to the composition effect of alloyed QDs. Compared with CdTe0.1Se0.9/CdZnS core/shell QDs, the introducing of CdZnS shells on CdTe0.05Se0.95
cores can exhibit better passivation effect on surface status, consequently leading to the red-shifted emission peaks in the range of 739–752 nm with the maximum PL QY reaching up to 45.09%. The unique PL properties of CdTeSe-based QDs in the red to NIR range make these core/shell QDs
attractive for future biological sensing and labeling applications.
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