van der Stam Ward, Bladt Eva, Rabouw Freddy T, Bals Sara, Donega Celso de Mello
Debye Institute for Nanomaterials Science, Utrecht University , P.O. Box 80000, 3508 TA Utrecht, The Netherlands.
Electron Microscopy for Materials Science (EMAT), University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
ACS Nano. 2015 Nov 24;9(11):11430-8. doi: 10.1021/acsnano.5b05496. Epub 2015 Oct 12.
The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu(+) extraction rate is coupled to the In(3+) incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source and Cu-extracting agent. In this way, Cu(+) ions can be extracted by trioctylphosphine ligands only when the In-P bond is broken. This results in readily available In(3+) ions at the same surface site from which the Cu(+) is extracted, making the process a direct place exchange reaction and shifting the overall energy balance in favor of the CE. Consequently, controlled cation exchange can occur even in large and anisotropic heterostructured nanocrystals with preservation of the size, shape, and heterostructuring of the template NCs into the product NCs. The cation exchange is self-limited, stopping when the ternary core/shell CuInSe2/CuInS2 composition is reached. The method is very versatile, successfully yielding a variety of luminescent CuInX2 (X = S, Se, and Te) quantum dots, nanorods, and HNCs, by using Cd-chalcogenide NCs and HNCs as templates. The approach reported here thus opens up routes toward materials with unprecedented properties, which would otherwise remain inaccessible.
直接合成结合不同三元半导体的异质纳米晶体（HNCs）具有挑战性，目前尚未成功。在此，我们报道了一种连续的拓扑阳离子交换（CE）途径，该途径可产生具有近红外发光的CuInSe2/CuInS2点核/棒壳纳米棒。在我们的方法中，通过使用化学计量的三辛基膦-InCl3络合物，将Cu(+)的萃取速率与In(3+)的掺入速率耦合，该络合物同时充当In源和Cu萃取剂。通过这种方式，只有当In-P键断裂时，三辛基膦配体才能萃取Cu(+)离子。这导致在与萃取Cu(+)相同的表面位点上有现成的In(3+)离子，使该过程成为直接的位置交换反应，并使整体能量平衡有利于CE。因此，即使在大型各向异性异质结构纳米晶体中也能发生可控的阳离子交换，同时将模板纳米晶体的尺寸、形状和异质结构保留到产物纳米晶体中。阳离子交换是自限性的，当达到三元核/壳CuInSe2/CuInS2组成时停止。该方法非常通用，通过使用Cd-硫族化物纳米晶体和HNCs作为模板，成功地制备了各种发光的CuInX2（X = S、Se和Te）量子点、纳米棒和HNCs。因此，本文报道的方法开辟了通往具有前所未有的性能的材料的途径，否则这些材料将无法获得。
