We investigate the effect of functionalization by acid/amine combinations of four aromatic capping ligands on the optoelectronic properties of CH₃NH₃PbBr₃ perovskite quantum dots (PQDs). These include benzoic acid (BA), phenylacetic acid (PAA), benzylamine, and isopropyl benzylamine. We observe that charge transfer efficiency in PQD films comprising BA-ligated samples varies between 12% and 95% as the dot density is tuned from 10² to 10⁵ dots/μm² but is consistently ∼92% over that entire range for PAA-ligated PQDs. As temperature T decreases, initially, recombination is dominated by bound or trapped excitons, but below 80 K, spectral broadening, accompanied by free excitonic behavior, is observed. Our results indicate enhanced charge delocalization at lower values of T, which reduces the level of exciton confinement and recombination decay rates and underlines the importance of investigating PQD–ligand interactions at a fundamental level given the significant effect minute changes in ligand structures have on the optoelectronic properties of quantum dots.

中文翻译：

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通过有机金属卤化物钙钛矿量子点中的表面修饰来调节电荷载流子动力学和传递。

我们调查的酸/胺组合的四个芳香族封顶配体的功能化对CH ₃ NH ₃ PbBr ₃钙钛矿量子点（PQDs）的光电性能的影响。这些包括苯甲酸（BA），苯乙酸（PAA），苄胺和异丙基苄胺。我们观察到在PQD膜，其电荷转移效率，包括BA-结扎样品12％和95％之间变化的点密度为10调谐²到10个⁵点/微米²，但始终〜92％，比对于PAA-该整个范围连接的PQD。作为温度T降低，最初，重组受束缚或捕获的激子支配，但低于80 K，观察到光谱展宽，伴随着自由激子行为。我们的结果表明，在较低的T值下，电荷的离域作用增强，这降低了激子的束缚和复合衰变速率，并着重指出了在基本水平上研究PQD-配体相互作用的重要性，因为配体结构的微小变化对光电子有显着影响量子点的性质。