De Chayan K, Roy Debjit, Mandal Saptarshi, Mandal Prasun K
J Phys Chem Lett. 2019 Aug 1;10(15):4330-4338. doi: 10.1021/acs.jpclett.9b01157. Epub 2019 Jul 19.
Suppressed blinking has been reported in large (diameter ∼14.1 nm) core/shell InP quantum dots (QDs) under reduced air environment. We report here suppressed blinking with approximately four times smaller (diameter ∼3.6 nm) core/alloy-shell/shell InP QDs under ambient air atmosphere. The ⟨ON fraction⟩ has been obtained to be 0.65. Approximately 26% of the single QDs exhibit ON fraction >80%. The smaller ON exponent (1.19) magnitude in comparison to the OFF exponent (1.45) indicates longer ON events are interrupted by smaller OFF events. ON event truncation time is ∼1.5 times that of the OFF event, signifying the detrapping rate is much higher than the trapping rate. Interestingly, the detrapping rate/trapping rate (single-particle level property) could be directly correlated to the photoluminescence quantum yield (ensemble level property). An additional exponential term required to fit the probability density distribution of the ON event duration could be correlated with hole trapping, leading to extended ON times (>60 s).
据报道，在空气减少的环境下，大尺寸（直径约14.1纳米）的核/壳型磷化铟量子点（QDs）会出现闪烁抑制现象。我们在此报告，在环境空气气氛下，尺寸约小四倍（直径约3.6纳米）的核/合金壳/壳型磷化铟量子点也出现了闪烁抑制现象。“开态分数”（⟨ON fraction⟩）为0.65。约26%的单个量子点的开态分数>80%。与关态指数（1.45）相比，开态指数（1.19）的幅度较小，这表明较长的开态事件会被较小的关态事件中断。开态事件截断时间约为关态事件的1.5倍，这意味着脱陷速率远高于陷获速率。有趣的是，脱陷速率/陷获速率（单粒子水平特性）可以直接与光致发光量子产率（整体水平特性）相关联。拟合开态事件持续时间概率密度分布所需的一个额外指数项可能与空穴陷获有关，从而导致开态时间延长（>60秒）。
