Radial 1-D nano-heterojunctions have distinct optoelectronic properties. However, their complex fabrication process is still the bottleneck of device applications. Herein, a facile atomic layer deposition (ALD) method was used to coat a polycrystalline CdS thin film with high uniformity and controllable thickness on the surface of the as-synthesized p-type ZnSe nanowires, for fabricating radial 1-D ZnSe-CdS nano-heterojunctions. The nano-heterojunctions exhibited excellent optoelectronic properties. Under blue/violet light, the nano-heterojunctions obtained a response radio of ∼5 × 10 3 , a responsitivity of ∼1.43 A/W, a gain of ∼3.78 and a detectivity of ∼0.57 × 10 12 cmHz 1/2 W −1 at zero bias. Furthermore, the nano-heterojunction also showed obvious photovoltaic characteristic with a power conversion efficiency of ∼0.96%. This method is expected to play an important role in nano-heterojunction construction and their device applications.
Zhi-Qiang Zhou,Yuan-Ping Liao,Jing Yang,Shan Huang,Qi Xiao,Li-Yun Yang,Yi Liu
Developing simple and sensitive non-aggregation strategy for detecting Cd 2+ is necessary for improving the selectivity and sensitivity of probe. Here, we establish a simple, rapid and ratiometric strategy for the recognition of Cd 2+ based on the formation of core-shell ZnSe/CdS structure using ZnSe quantum dots (QDs). The transformation from binary ZnSe QDs to core-shell ZnSe/CdS QDs both change the elemental composition and structure of ZnSe QDs, leading to the changes in band gap of ZnSe QDs, which could be observed in the UV–vis spectra. In the detection process, ZnSe QDs only possess absorption peak at 343 nm, the formation of ZnSe/CdS after the addition of Cd 2+ leads to the appearance of the new peak at 397 nm, while other heavy metal ions could not cause the appearance of new absorption peak. Therefore, this strategy shows good selectivity for Cd 2+ detection. Based on this strategy, the limit of detection (LOD) for Cd 2+ is 11 nM by UV–vis spectroscopy with a desirable relation of linearity (R 2 = 0.999) between A 397 /A 343 and Cd 2+ contents, which is superior to the LOD of most reported nanomaterials . The response time for Cd 2+ detection is as short as 60 s, which is suitable for rapid detection. This ratiometric probe has also been applied to the detection of Cd 2+ in tap water samples, the recovery of Cd 2+ was between 94.9% and 105.6% for tap water samples, indicating the high accuracy of our ratiometric assay. Our strategy not only provided a new method for detecting Cd 2+ , but also put forward an implication that the band energy changes of QDs caused by heavy metal ions can be applied in the selective and sensitive detection of heavy metal ions.
Mingrui Liu,Guangmin Li,Shunsheng Wei,Hongfei Liu,Gaoling Yang
Chiral semiconductor nanocrystals (NCs) represent a promising class of materials for various applications, including biological sensing, photonics, and spin-polarized devices. However, the comprehension of the mechanisms underlying ligand-induced chiroptical effects in NCs has been limited by the constraints of current theoretical and experimental models, particularly those involving simple spherical NCs. In this study, we examined the relationship between optical activity and band structures in core–shell dot-in-rod NCs, specifically CdSe@CdS, ZnSe/CdS@CdS, and ZnSeTe/CdS@CdS dot-in-rod NCs, which were functionalized with chiral ligands. By manipulating the wave function distribution of electrons and holes within the dot-in-rod NCs, we demonstrated through circular dichroism (CD) measurements that a reduction in the number of holes within the synthesized dot-in-rod NCs correlates with a decrease in the g factor. This conclusion was corroborated by theoretical calculations. Furthermore, the fabrication of chiral CdS-Au heterojunctions and the application of electron quenchers revealed that the reduction of the g factor also suggests the significant role of electrons in the generation of chirality. Our findings not only enhance the understanding of the fundamental origins of induced chirality effects in semiconductor NCs but also provide a clear methodology for the design of optimal optically active chiral NCs, thereby paving the way for future applications utilizing chiroptical materials.
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