Size Dependent Optical Properties and Structure of ZnS Nanocrystals Prepared from a Library of Thioureas
Size Dependent Optical Properties and Structure of ZnS Nanocrystals Prepared from a Library of Thioureas
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DOI：
10.1021/acs.chemmater.1c03432
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发表时间：
2022-01-06
影响因子：
8.6
通讯作者：
Owen, Jonathan S.
中科院分区：
文献类型：
--
作者：
Bennett, Ellie;Greenberg, Matthew W.;Owen, Jonathan S.
由Zn（O_2CR）（2）（O_2CR =十四烷酸盐、油酸盐和2-己基癸酸盐）、N，N ′-二取代和N，N ′，N ′-三取代硫脲和P，P，N-三取代膦硫代酰胺合成了ZnS纳米晶（λ（max）（1 S（e）-1S（3/2 h））= 260-320 nm，d = 1.7-10.0 nm）。评价了前体取代、配体空间位阻和反应温度对最终粒径的影响。使用饱和烃溶剂和饱和脂肪族羧酸酯配体，可以避免聚合物副产物，并分离纯ZnS纳米晶体。升高的温度、较慢的前体转化反应性和支链2-己基癸酸锌产生最大的ZnS纳米晶体。仔细纯化的羧酸锌，快速转化前体，并在完全前体转化后冷却合成混合物，提供具有最大形状分散度的准球形纳米晶体。纳米晶体的尺寸测量使用对分布函数（PDF）分析的X射线散射和扫描透射电子显微镜（STEM）和绘制相对于其第一激子光吸收的能量。由此产生的经验关系提供了一个有用的方法来表征从1.7到4.0 nm的尺寸使用光学吸收光谱。
ZnS nanocrystals (lambda(max)(1S(e)-1S(3/2h)) = 260-320 nm, d = 1.7-10.0 nm) are synthesized from Zn(O2CR)(2) (O2CR = tetradecanoate, oleate and 2-hexyldecanoate), N,N'-disubstituted and N,N',N'-trisubstituted thioureas, and P,P,N-trisubstituted phosphane-carbothioamides. The influence of precursor substitution, ligand sterics, and reaction temperature on the final nanocrystal size was evaluated. Using saturated hydrocarbon solvents and saturated aliphatic carboxylate ligands, polymeric byproducts could be avoided and pure ZnS nanocrystals isolated. Elevated temperatures, slower precursor conversion reactivity, and branched zinc 2-hexyldecanoate yield the largest ZnS nanocrystals. Carefully purified zinc carboxylate, rapidly converting precursors, and cooling the synthesis mixture following complete precursor conversion provide quasispherical nanocrystals with the narrowest shape dispersity. Nanocrystal sizes were measured using pair distribution function (PDF) analysis of X-ray scattering and scanning transmission electron microscopy (STEM) and plotted versus the energy of their first excitonic optical absorption. The resulting empirical relationship provides a useful method to characterize the nanocrystal size from 1.7 to 4.0 nm using optical absorption spectroscopy.