School of Electronic Engineering, Heilongjiang University, Harbin 150080, China.
J Colloid Interface Sci. 2011 May 15;357(2):331-5. doi: 10.1016/j.jcis.2011.02.014. Epub 2011 Feb 12.
Energy transfer (ET) processes between quantum dots (QDS) were investigated by means of steady-state and time-resolved up-conversion luminescence measurements. Two types of CdSeS QDs with different Se/S molar ratios at the similar sizes of ~4.5 nm emit green and orange up-conversion luminescence at infrared laser excitation, separately. The power dependence and nanosecond luminescent decays of QDs films demonstrated that up-conversion luminescence was attributed to two-photon absorption and ET process occurred from green-emitting QDs to orange-emitting QDs. The ET rate was estimated quantitatively to be 0.03 ns(-1) by Dexter theory. The decrease of ET rate is due to Se doped substituted in the Sulfur sites. The band-edge excitonic state is predominating at the initial time evolution and responsible for peak shift and ET. The surface emission of orange-emitting QDs becomes slower, and is attributed to the trapping of electrons from QDs donors.
通过稳态和时间分辨上转换荧光测量研究了量子点（QDS）之间的能量转移（ET）过程。两种具有不同硒/硫摩尔比的 CdSeS QDs 在相似的~4.5nm 尺寸下，分别在红外激光激发下发射绿色和橙色上转换荧光。QDs 薄膜的功率依赖性和纳秒荧光衰减表明，上转换荧光归因于双光子吸收，并且 ET 过程从绿色发射 QDs 到橙色发射 QDs 发生。通过 Dexter 理论定量估计 ET 速率为 0.03 ns(-1)。ET 速率的降低是由于硒掺杂取代了硫位。在初始时间演化中，带边激子态占主导地位，负责峰位移和 ET。橙色发射 QDs 的表面发射变得更慢，这归因于从 QDs 供体捕获电子。
