Busatto Serena, Ruiter Mariska de, Jastrzebski Johann T B H, Albrecht Wiebke, Pinchetti Valerio, Brovelli Sergio, Bals Sara, Moret Marc-Etienne, de Mello Donega Celso
Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands.
Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
ACS Nano. 2020 Oct 27;14(10):13146-13160. doi: 10.1021/acsnano.0c04744. Epub 2020 Sep 16.
Despite recent advances, the synthesis of colloidal InSb quantum dots (QDs) remains underdeveloped, mostly due to the lack of suitable precursors. In this work, we use Lewis acid-base interactions between Sb(III) and In(III) species formed at room temperature from commercially available compounds (, InCl, Sb[NMe] and a primary alkylamine) to obtain InSb adduct complexes. These complexes are successfully used as precursors for the synthesis of colloidal InSb QDs ranging from 2.8 to 18.2 nm in diameter by fast coreduction at sufficiently high temperatures (≥230 °C). Our findings allow us to propose a formation mechanism for the QDs synthesized in our work, which is based on a nonclassical nucleation event, followed by aggregative growth. This yields ensembles with multimodal size distributions, which can be fractionated in subensembles with relatively narrow polydispersity by postsynthetic size fractionation. InSb QDs with diameters below 7.0 nm have the zinc blende crystal structure, while ensembles of larger QDs (≥10 nm) consist of a mixture of wurtzite and zinc blende QDs. The QDs exhibit photoluminescence with small Stokes shifts and short radiative lifetimes, implying that the emission is due to band-edge recombination and that the direct nature of the bandgap of bulk InSb is preserved in InSb QDs. Finally, we constructed a sizing curve correlating the peak position of the lowest energy absorption transition with the QD diameters, which shows that the band gap of colloidal InSb QDs increases with size reduction following a 1/ dependence.
尽管最近取得了进展，但胶体InSb量子点（QDs）的合成仍然不够成熟，主要原因是缺乏合适的前驱体。在这项工作中，我们利用室温下由市售化合物（InCl、Sb[NMe]和一种伯烷基胺）形成的Sb(III)和In(III)物种之间的路易斯酸碱相互作用来获得InSb加合物络合物。这些络合物通过在足够高的温度（≥230°C）下快速共还原，成功地用作合成直径范围为2.8至18.2 nm的胶体InSb量子点的前驱体。我们的发现使我们能够提出在我们的工作中合成的量子点的形成机制，该机制基于非经典成核事件，随后是聚集生长。这产生了具有多峰尺寸分布的集合体，通过合成后尺寸分级可以将其分离为具有相对窄多分散性的子集合体。直径小于7.0 nm的InSb量子点具有闪锌矿晶体结构，而较大量子点（≥10 nm）的集合体由纤锌矿和闪锌矿量子点的混合物组成。这些量子点表现出具有小斯托克斯位移和短辐射寿命的光致发光，这意味着发射是由于带边复合，并且块状InSb带隙的直接性质在InSb量子点中得以保留。最后，我们构建了一条将最低能量吸收跃迁的峰值位置与量子点直径相关联的尺寸曲线，该曲线表明胶体InSb量子点的带隙随着尺寸减小遵循1/依赖性而增加。
