Oriented attachment can generate wide range of nanomaterials with unusual morphologies, and is typically driven by reducing their surface energy during crystal growth (1). However, it is not completely understood why anisotropic nanostructures can be formed via oriented attachment when they lacks anisotropic crystal symmetry, as shown in examples of nanowires, nanorods, and nanosheets of lead (Pb) chalcogenide (2-4). So far, inhomogeneous surface dipole or soft template formation of surfactant molecules has been discusses as a key role in oriented attachment of those examples; but it is yet still challenging to achieve precise control over size and shape of Pb chalcogenide nanostructures, which is important to control their carrier dynamics and charge transport (5).
Here we will discuss our recent development on 1D and 2D nanostructures of Pb chalcogenides. Chemical engineering of crystal growth in Pb chalcogenide allows rational control of their morphology and composition, which also tailors their optical and electrical properties. Especially due to the large Bohr radius (PbS 18 nm, PbSe 46 nm) and narrow band gap (PbS 0.41 eV, PbSe 0.28 eV) of Pb chalcogenides (6), the above mentioned Pb chalcogenide nanostructures exhibit the effect of quantum confinement of carriers. We will explore how asymmetric confinement of carrier is manifested in the characteristics of charge carriers, exciton dynamics, and other optoelectric properties for these Pb chalcogenide nanostructures based on theoretical and spectroscopy studies. Furthermore, there are huge opportunities of Pb chalcogenide nanostructures in photovoltaics, sensors, transistors and other optoelectronic devices. We will discuss how the unique properties of anisotropic nanostructures can be utilized for those applications.
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