Synthesis of Ternary and Quaternary Group III-Arsenide Colloidal Quantum Dots via High-Temperature Cation Exchange in Molten Salts: The Importance of Molten Salt Speciation
Synthesis of Ternary and Quaternary Group III-Arsenide Colloidal Quantum Dots via High-Temperature Cation Exchange in Molten Salts: The Importance of Molten Salt Speciation
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DOI：
10.1021/acsnano.3c09490
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发表时间：
2023-12-18
期刊：
影响因子：
17.1
通讯作者：
Talapin，Dmitri V.
中科院分区：
文献类型：
--
作者：
Ondry，Justin C.;Gupta，Aritrajit;Talapin，Dmitri V.
胶体半导体纳米晶是一类重要的光电材料，具有许多理想的光电性能。在其体相中，含镓和铝的III-V族材料如GaAs、GaP和Al 1-xGaxAs代表了一些技术上最重要的半导体。然而，由于结晶这些高度共价的材料所需的高温以及Ga-和Al-前体在这样的高温下对有机溶剂的极端反应性，通过传统方法的胶体合成是困难的。最近开发的这些材料合成的范式转变是使用熔融无机盐作为溶剂，通过相应的磷属元素化铟（InPn）胶体纳米晶体的阳离子交换来制备含Ga的III-V胶体纳米晶体。已经有几个成功的应用熔融盐溶剂制备III-磷化物胶体纳米晶体。然而，很少有人知道这些反应环境的性质在相关的反应条件和III-砷化物胶体纳米晶体的合成仍然具有挑战性。在此，我们报告了一个详细的研究，使用名义上刘易斯基本熔盐溶剂添加镓卤化物的阳离子交换的InPn纳米晶体。令人惊讶的是，这些盐体系相分离成两个不混溶的相，并且纳米晶体优先分离到其中一个相。利用一套原位光谱工具，我们确定了纳米晶体的相分离为刘易斯中性碱金属四卤镓酸盐熔盐。我们applyin原位高温拉曼光谱，以确定在实验相关的反应条件下，在几种熔融盐组合物中存在的化学物种，以阐明所观察到的反应性的分子基础。然后，我们采用刘易斯中性KGaI 4熔盐制备高品质的In 1-xGaxAs和In 1-xGaxP纳米晶体，并证明偏离刘易斯中性条件加速III-砷化物材料的分解。此外，我们扩展到KAlI 4基熔盐制备In 1-x-yGaxAlyAs纳米晶体，这是溶液合成的季铵III-V纳米晶体的一个例子。这些见解为熔盐溶剂的合理开发提供了分子基础，从而允许制备多种多组分III-V胶体纳米晶体阵列。
Colloidal semiconductor nanocrystals are an important class of materials which have many desirable optoelectronic properties. In their bulk phases, gallium- and aluminum-containing III–V materials such as GaAs, GaP, and Al1–xGaxAs represent some of the most technologically important semiconductors. However, their colloidal synthesis by traditional methods is difficult due to the high temperatures needed to crystallize these highly covalent materials and the extreme reactivity of Ga- and Al- precursors toward organic solvents at such high temperatures. A recently developed paradigm shift in the synthesis of these materials is to use molten inorganic salts as solvents to prepare Ga- containing III–V colloidal nanocrystals by cation exchange of the corresponding indium pnictide (InPn) colloidal nanocrystals. There have been several successful applications of molten salt solvents to prepare III-phosphide colloidal nanocrystals. However, little is known about the nature of these reaction environments at the relevant reaction conditions and synthesis of III-arsenide colloidal nanocrystals remains challenging. Herein we report a detailed study on cation exchange of InPn nanocrystals using nominally Lewis basic molten salt solvents with added gallium halides. Surprisingly, these salt systems phase separate into two immiscible phases, and the nanocrystals preferentially segregate to one of the phases. Using a suite ofin situspectroscopy tools, we identify the phase the nanocrystals segregate to as Lewis neutral alkali tetrahalogallate molten salts. We applyin situhigh-temperature Raman spectroscopy to identify the chemical species present in several molten salt compositions at experimentally relevant reaction conditions to elucidate a molecular basis for the reactivity observed. We then employ Lewis neutral KGaI4molten salts to prepare high-quality In1–xGaxAs and In1–xGaxP nanocrystals and demonstrate that deviation from Lewis neutral conditions accelerate nanocrystal decomposition in the case of III-arsenide materials. Further, we expand to KAlI4-based molten salts to prepare In1–x–yGaxAlyAs nanocrystals which represent an example of solution-synthesizedquaternaryIII–V nanocrystals. These insights provide a molecular basis for the rational development of molten salt solvents, thus allowing the preparation of a diverse array of multicomponent III–V colloidal nanocrystals.