InP 量子点的表面化学、胺-卤化物共钝化和 Z 型配体的结合,Chemistry of Materials

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InP 量子点的表面化学、胺-卤化物共钝化和 Z 型配体的结合
Chemistry of Materials ( IF 7.2 ) Pub Date : 2023-01-20 , DOI: 10.1021/acs.chemmater.2c02960
Kim Corinna Dümbgen _{1,

2} , Jari Leemans _{1,

2} , Vic De Roo ₃ , Matthias Minjauw ₄ , Christophe Detavernier ₄ , Zeger Hens _{1,

2}

Affiliation

了解和控制胶体量子点 (QD) 的表面化学是改善其光电特性和为特定应用定制材料的重要步骤。对于使用二乙基氨基膦 (DEAP) 合成的油胺-氯化物共钝化 InP QD，可能的交换反应及其对 QD 特性的影响的知识仍然非常有限。在这项工作中，我们通过结合实验和计算研究来解决这个问题。首先，我们证明 InP QD 被油胺 (OlNH ₂) 和氯化物，分别结合为 L 型和 X 型配体。通过暴露于有机酸（如羧酸或硫醇），这种 L-X 组合可以在酸碱介导的配体交换反应中被油基氯化铵取代，该反应导致羧酸盐或硫醇盐作为 X 型配体结合。后者倾向于通过在硫醇盐的硫原子上形成强烈局域化的中间隙态来淬灭带边发射。_{此外，我们观察到 ZnCl 2}与 InP QD 表面的结合，这一过程是由该 Z 型配体与 OlNH _{2的先前络合实现的}，大大增加了带边发射。然而，由于由此产生的光致发光效率仍然适中，我们得出结论，使用 DEAP 合成的 InP QD 具有多种表面状态，其钝化至少取决于配位不足的表面磷的消除和 X 型配体的选择。

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Surface Chemistry of InP Quantum Dots, Amine–Halide Co-Passivation, and Binding of Z-Type Ligands

Understanding and controlling the surface chemistry of colloidal quantum dots (QDs) are essential steps toward improving their opto-electronic properties and tailoring the material for specific applications. For oleylamine–chloride co-passivated InP QDs synthesized using di-ethylaminophosphine (DEAP), knowledge of possible exchange reactions and their effect on the QD properties is still very limited. In this work, we address this issue by a combination of experimental and computational studies. First, we prove that InP QDs are passivated by a combination of oleylamine (OlNH₂) and chloride, bound as L-type and X-type ligands, respectively. By exposure to organic acids such as carboxylic acids or thiols, this L–X combination can be replaced with oleylammonium chloride in an acid–base-mediated ligand exchange reaction that results in the binding of carboxylates or thiolates as X-type ligands. The latter tend to quench the band-edge emission by forming strongly localized mid-gap states on the sulfur atoms of the thiolates. Furthermore, we observe that the binding of ZnCl₂ to the InP QD surface, a process enabled by the prior complexation of this Z-type ligand with OlNH₂, considerably increases the band-edge emission. However, as the resulting photoluminescence efficiency remains modest, we conclude that InP QDs synthesized using DEAP feature a diverse set of surface states, for which passivation depends at least on the elimination of undercoordinated surface phosphorous and the choice of the X-type ligand.

更新日期：2023-01-20

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