Perovskite and chalcogenide quantum dots (QDs) are important nano semiconductors. It has been a challenge to synthesize heterostructural QDs combining perovskite and chalcogenide with tailorable photoelectronic properties. In this report, heterostructural CsPbX3-PbS (X = Cl, Br, I) QDs were successfully synthesized via a room temperature in situ transformation route. The CsPbX3-PbS QDs show a tunable dual emission feature with the visible and near-infrared (NIR) photoluminescence (PL) corresponding to CsPbX3 and PbS, respectively. Typically, the formation and evolution of the heterostructural CsPbBr3–PbS QDs with reaction time was investigated. Femtosecond transient absorption spectroscopy (TAS) was applied to illuminate the exciton dynamics in CsPbBr3–PbS QDs. The mild synthetic method and TAS proved perovskite to PbS energy transfer may pave the way toward highly efficient QD photovoltaic and optoelectronic devices.

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A concise method is proposed to fabricate L-shaped Ag nanostructures (LSANs) for generating chirality. Prepared by glancing angle deposition, the LSAN composed of two slices with different thickness is stacked on self-assembled monolayer polystyrene nanosphere arrays by controlling substrate azimuth and deposition time. The strong optical chirality of LSANs is achieved in visible and near-IR regions by measurement. For the circular dichroism spectrum of LSANs, the intensity is enlarged, and its peaks red-shift with increasing thickness difference. When LSANs are stacked on polystyrene spheres of different diameters, enlargement and red-shift are also observed in their circular dichroism spectra with increasing thickness difference. The numerical calculations of finite element method show that the two slices composing LSAN provide cross-electric dipoles and their thickness difference provides phase difference for generating optical chirality. This study not only provides a concise and scalable method for fabricating chiral plasmonic nanostructures but also contributes to understand the knowledge of the mechanism of circular dichroism.

CsPbX 3 (X = Cl, Br, I) perovskite nanowires and nanorods are important 1D and quasi 1D semiconductor nanomaterials. They have shown significant prospect in optic and optoelectronic applications, especially for their adaptability to flexible devices, good carrier transport performance, polarized absorption, and emission properties. Due to the high dependence of the property to the morphology, it is crucial to develop synthesis methods with continuous diameter and length tunability of the 1D/quasi 1D perovskites. In this report, a feasibly room temperature synthesis method was developed for ultrathin CsPbX 3 (X = Cl, Br, I) perovskite nanowires. By aging the CsPbBr 3 nanowires (≈2*500 nm) under ambient condition with proper concentration and time, the nanowires are transformed to nanorods with controllable diameter and length. Reversibly, the nanorods can be transformed back to nanowires. Equilibrium mechanism is adopted to understand the morphology evolution, and hopefully could be generally applied to many other nano materials. The polarized optoelectronic properties of the nanowires and nanorods are interpreted by a model based on the two-channel anisotropies measurement. Polarized light detectors constructed by oriented assembled nanowires are fabricated to demonstrate their application potentials.

The unique photonic effect of self-assembled metal nanoparticles is widely used in many applications. In this article, we prepared self-assembled gold nanorod (GNR) vertical arrays substrate by an evaporation method and found that the morphology of the substrate can be effectively regulated by changing the immersion time in the target molecules solution to obtain different Raman enhancement effects. We separately calculated the local electromagnetic field of the GNR vertical arrays and disorder substrate by the finite element method (FEM), which was consistent with the experimental results. Based on optimal soaking time, the sensitivity, reproducibility, and stability of substrates were separately studied. The experimental results show that the GNR vertical arrays can detect Rhodamine 6G (Rh6G) at concentrations as low as 10 −11 M and exhibit good reproducibility and stability due to local electromagnetic (EM) field enhancement caused by the coupling of adjacent nanorods. Thus, our work can demonstrate that the substrate has excellent surface-enhanced Raman scattering (SERS) activity and the obtained GNR vertical arrays have great potential for biosensor and biodetection.

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Chiral plasmonic nanostructures (CPNs) with a strong chiroptical response in visible and near-infrared regions were fabricated with homemade SiO2 chiral templates through oblique angle deposition. The circular dichroism spectra of the CPNs showed that the chiroptical response was amplified with increased deposition thickness of silver. Simulation results demonstrated that only the magnetic dipole mode was excited when the deposition thickness was small. Magnetic and electric dipoles emerged and coupled to each other with increased silver deposition thickness. As a result, chiroptical enlargement occurred. This study provides a concise method of fabricating CPNs with a tunable chiroptical response.

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