Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
Nat Commun. 2019 Jan 2;10(1):2. doi: 10.1038/s41467-018-07837-z.
Semiconductor heterostructure nanocrystals, especially with core/shell architectures, are important for numerous applications. Here we show that by decreasing the shell growth rate the morphology of ZnS shells on ZnSe quantum rods can be tuned from flat to islands-like, which decreases the interfacial strain energy. Further reduced growth speed, approaching the thermodynamic limit, leads to coherent shell growth forming unique helical-shell morphology. This reveals a template-free mechanism for induced chirality at the nanoscale. The helical morphology minimizes the sum of the strain and surface energy and maintains band gap emission due to its coherent core/shell interface without traps, unlike the other morphologies. Reaching the thermodynamic controlled growth regime for colloidal semiconductor core/shell nanocrystals thus offers morphologies with clear impact on their applicative potential.
半导体异质结构纳米晶体，尤其是具有核/壳结构的纳米晶体，在许多应用中都非常重要。在这里，我们表明通过降低壳层生长速率，可以将 ZnS 壳层在 ZnSe 量子棒上的形态从平面调整为岛状，从而降低界面应变能。进一步降低生长速度，接近热力学极限，会导致壳层的相干生长，形成独特的螺旋壳形态。这揭示了在纳米尺度上诱导手性的无模板机制。由于其具有无陷阱的相干核/壳界面，螺旋形态最小化了应变能和表面能的总和，并保持了带隙发射，这与其他形态不同。对于胶体半导体核/壳纳米晶体，达到热力学控制的生长状态，因此可以提供对其应用潜力有明显影响的形态。
