Yadav Ranjana, Kwon Yongju, Rivaux Céline, Saint-Pierre Christine, Ling Wai Li, Reiss Peter
Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France.
Univ. Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France.
J Am Chem Soc. 2023 Mar 15;145(10):5970-5981. doi: 10.1021/jacs.2c13834. Epub 2023 Mar 3.
Nonpyrophoric aminophosphines reacted with indium(III) halides in the presence of zinc chloride have emerged as promising phosphorus precursors in the synthesis of colloidal indium phosphide (InP) quantum dots (QDs). Nonetheless, due to the required P/In ratio of 4:1, it remains challenging to prepare large-sized (>5 nm), near-infrared absorbing/emitting InP QDs using this synthetic scheme. Furthermore, the addition of zinc chloride leads to structural disorder and the formation of shallow trap states inducing spectral broadening. To overcome these limitations, we introduce a synthetic approach relying on the use of indium(I) halide, which acts as both the indium source and reducing agent for aminophosphine. The developed zinc-free, single-injection method gives access to tetrahedral InP QDs with an edge length > 10 nm and narrow size distribution. The first excitonic peak is tunable from 450 to 700 nm by changing the indium halide (InI, InBr, InCl). Kinetic studies using phosphorus NMR reveal the coexistence of two reaction pathways, the reduction of transaminated aminophosphine by In(I) and via redox disproportionation. Etching the surface of the obtained InP QDs at room temperature with -generated hydrofluoric acid (HF) leads to strong photoluminescence (PL) emission with a quantum yield approaching 80%. Alternatively, surface passivation of the InP core QDs was achieved by low-temperature (140 °C) ZnS shelling using the monomolecular precursor zinc diethyldithiocarbamate. The obtained InP/ZnS core/shell QDs that emit in a range of 507-728 nm exhibit a small Stokes shift (110-120 meV) and a narrow PL line width (112 meV at 728 nm).
在氯化锌存在下，非自燃性氨基膦与卤化铟（III）反应，已成为合成胶体磷化铟（InP）量子点（QDs）中很有前景的磷前驱体。尽管如此，由于所需的P/In比为4:1，使用这种合成方案制备大尺寸（>5 nm）、近红外吸收/发射的InP量子点仍然具有挑战性。此外，氯化锌的加入会导致结构无序并形成浅陷阱态，从而引起光谱展宽。为了克服这些限制，我们引入了一种依赖于使用卤化铟（I）的合成方法，卤化铟（I）既作为铟源又作为氨基膦的还原剂。所开发的无锌单注射法可制备边长>10 nm且尺寸分布窄的四面体InP量子点。通过改变卤化铟（InI、InBr、InCl），第一个激子峰可在450至700 nm范围内调谐。使用磷核磁共振的动力学研究揭示了两种反应途径的共存，即In（I）对转氨基氨基膦的还原以及通过氧化还原歧化反应的还原。在室温下用原位生成的氢氟酸（HF）蚀刻所得InP量子点的表面，会产生强的光致发光（PL）发射，量子产率接近80%。或者，通过使用单分子前驱体二乙基二硫代氨基甲酸锌在低温（140°C）下进行ZnS壳层包覆，实现了InP核量子点的表面钝化。所获得的在507 - 728 nm范围内发射的InP/ZnS核/壳量子点表现出小的斯托克斯位移（110 - 120 meV）和窄的PL线宽（在728 nm处为112 meV）。
