Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
ACS Nano. 2010 Mar 23;4(3):1545-52. doi: 10.1021/nn901808f.
The exciton quenching dynamics of single CdSe/CdS(3ML)ZnCdS(2ML)ZnS(2ML) core/multishell QDs adsorbed on glass, In2O3, and ITO have been compared. Single QDs on In2O3 show shorter fluorescence lifetimes and higher blinking frequencies than those on glass because of interfacial electron transfer from QDs to In2O3. Compared to glass and In2O3, single QDs on ITO show suppressed blinking activity as well as reduced fluorescence lifetimes. For QDs in contact with the n-doped ITO, the equilibration of their Fermi levels leads to the formation of negatively charged QDs. In these negatively charged QDs, the off states are suppressed because of the effective removal of the valence band holes, and their fluorescence lifetimes are shortened because of exciton Auger recombination and hole transfer processes involving the additional electrons. This study shows that the blinking of single QDs can be effectively suppressed on the surface of ITO. This phenomenon may also be observable for other QDs and on different n-doped semiconductors.
已比较了吸附在玻璃、In2O3 和 ITO 上的单个 CdSe/CdS(3ML)ZnCdS(2ML)ZnS(2ML)核/多壳 QD 的激子猝灭动力学。由于电子从 QD 到 In2O3 的界面转移，In2O3 上的单个 QD 表现出比玻璃上更短的荧光寿命和更高的闪烁频率。与玻璃和 In2O3 相比，ITO 上的单个 QD 表现出抑制的闪烁活性以及降低的荧光寿命。对于与 n 型掺杂 ITO 接触的 QD，它们费米能级的平衡导致形成带负电的 QD。在这些带负电的 QD 中，由于有效去除价带空穴，关闭状态被抑制，并且由于涉及额外电子的激子俄歇复合和空穴转移过程，它们的荧光寿命缩短。本研究表明，单个 QD 的闪烁可以在 ITO 表面上有效抑制。这种现象也可能在其他 QD 和不同的 n 型掺杂半导体上观察到。
