配体平衡影响CsPbBr3中的光致发光闪烁：宽场成像数据的变点分析
Ligand Equilibrium Influences Photoluminescence Blinking in CsPbBr3: A Change Point Analysis of Widefield Imaging Data
AI总结：
本研究针对钙钛矿量子点光致发光间歇性问题，通过变点分析宽场成像数据，发现卵磷脂配体因结合亲和力更强可显著抑制CsPbBr3量子点闪烁，为量子点表面钝化和闪烁抑制提供了新方向。
摘要：
光致发光间歇性仍是实现钙钛矿量子点（QDs）作为可扩展单光子发射器的最大挑战之一。我们对比了分别以卵磷脂、油酸与油胺组合作为包覆配体的CsPbBr3量子点，以阐明表面化学对光致发光间歇性的作用。我们采用宽场光致发光显微镜，对数百个量子点的闪烁行为进行采样。通过变点分析，我们实现了对闪烁轨迹的可靠分类，并分析了来自大量量子点的代表性分布（卵磷脂组样本量N=1308，油酸/油胺组样本量N=1317）。研究发现，与油酸/油胺相比，卵磷脂可抑制CsPbBr3量子点的闪烁。在常规实验条件下，尽管两种量子点的溶液光致发光量子产率几乎相同，但卵磷脂包覆的量子点处于非闪烁状态的概率是前者的7.5倍，处于最高发射态的时长是前者的2.5倍。我们测量了光致发光随稀释度的变化，结果表明卵磷脂与油酸/油胺包覆的差异在单颗粒实验制备过程的低浓度下显现。结合实验与第一性原理计算，我们将卵磷脂与油酸/油胺的性能差异归因于二者配体结合平衡的不同。与我们的实验数据一致，密度泛函理论计算表明，相较于油酸/油胺，卵磷脂对量子点表面的结合亲和力更强，这意味着稀释过程中配体解吸的可能性更低。这些结果表明，对于单颗粒和量子光实验中使用的钙钛矿量子点，采用结合更紧密的配体是实现表面钝化进而减少闪烁的必要条件。
英文摘要：
Photoluminescence intermittency remains one of the biggest challenges to realizing perovskite quantum dots (QDs) as scalable single photon emitters. We compare CsPbBr3 QDs capped with different ligands, lecithin, and a combination of oleic acid and oleylamine, to elucidate the role of surface chemistry on photoluminescence intermittency. We employ widefield photoluminescence microscopy, sampling the blinking behavior of hundreds of QDs. Using change point analysis, we achieve the robust classification of blinking trajectories, and we analyze representative distributions from large numbers of QDs (Nlecithin = 1308, Noleic acid/oleylamine =1317). We find that lecithin suppresses blinking in CsPbBr3 QDs compared to oleic acid/oleylamine. Under common experimental conditions, lecithin-capped QDs are 7.5 times more likely to be non-blinking and spend 2.5 times longer in their most emissive state, despite both QDs having nearly identical solution photoluminescence quantum yields. We measure photoluminescence as a function of dilution and show that the differences between lecithin and oleic acid/oleylamine capping emerge at low concentrations during preparation for single particle experiments. From experiment and first principles calculations, we attribute the differences in lecithin and oleic acid/oleylamine performance to differences in their ligand binding equilibria. Consistent with our experimental data, density functional theory calculations suggest a stronger binding affinity of lecithin to the QD surface compared to oleic acid/oleylamine, implying a reduced likelihood of ligand desorption during dilution. These results suggest that using more tightly binding ligands is a necessity for surface passivation and consequently, blinking reduction in perovskite QDs used for single particle and quantum light experiments.
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