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Zhang Jiatao’s Team of BIT Made Progress in Semiconductor Nanocrystalline Materials Devices

release date :2019-03-20 10:39:00  |   [ close window ]ViewCount:

    Translator: News Agency of BIT, Han Yu

    Editor: News Agency of BIT

  The quantum size effect and the confinement effect caused by the morphology and size regulation have become one of the most important discoveries in the field of nanomaterials, inspiring a new understanding at the nanoscale, especially semiconductor nanocrystalline materials. As feature sizes for optoelectronic, information, and new energy applications continue to decrease, device applications raise higher demands on the micro/nano structures and heterogenous-interface of semiconductor nanocrystalline materials. While physics/chemical properties are regulated and controlled by size, morphology, one of the bottlenecks is the interface control and device-level assembly with its performance application caused by impurity and energy band engineering research.

  Supported by Experiment Center of Advanced Materials (ECAM) platform of BIT and funded by the School's Innovative Talents Special Funding Program and the National Natural Science Foundation of China, Zhang Jiatao's research team established a new method for the preparation of reverse-competing cation exchange reactions from the perspectives of new methods, new structures and new properties, which stabilized the stable heterogeneous doping of II-VI semiconductor nanocrystals and the precise regulation heterogeneous interface with metal heterostructures. Recently, a series of advances have been made in the application of efficient plasmonic Au/CdSe nanodumbbell for photoelectrochemical hydrogen generation beyond visible region (>700nm), hydrophilic doped quantum dots “Ink” and their inkjet‐printed patterns for dual mode anticounterfeiting by reversible cation exchange mechanism, and Au@HgxCd1-xTe core@shell nanorods by sequential aqueous cation exchange for near-infrared photodetectors.

  The team collaborated with the Academician Li Can of the Dalian Institute of Chemical Physics of Chinese Academy of Sciences. Based on the accumulation of metal@ semiconductor heterstructures (Science, 2010; Adv. Mater., 2014; Angew. Chem. Int. Ed., 2015; Adv. Mater, 2016; Nano Energy, 2018; Nano Energy, 2019; J. Mater. Chem. Mater. A, 2018), by precisely controlling selenization reaction of Au/Ag core/shell nano crystalline and reverse-competing aqueous cation exchange reaction, the team prepared the Au/CdSe heterogeneous nanorods from core/shell to nanodumbbell evolution and established the heterogeneous interfaces. Attributed to the longitudinal SPR effect of the Au rod and the electromagnetic field enhancement "hot spots" at both ends and the high-quality heterogeneous interface, the prepared Au/CdSe HNRs have strong light absorption characteristics in the near-infrared region, realizing the plasmonic electron with efficient heat injection effect. Combined with spatially resolved surface photovoltage imaging characterization (in collaboration with Academician Li Can), they have successfully developed a kind of photoelectrocatalytic material with high absorption efficiency in the near-infrared band and a high visible-near-infrared photocatalytic hydrogen production performance, and its Faradic Efficiency is up to 96%. Photoelectrocatalytic hydrogen production activity (45.29 μmol cm-2 h-1) was not significantly reduced after 5 days of continuous testing. Dr. Wang Hongzhi from BIT and Dr. Gao Yuying from Dalian Institute of Chemical Physics are co-first authors. Related work entitled "Efficient plasmonic Au/CdSe Nano-dumbbell for Photoelectrochemical Hydrogen Generation beyond Visible Region" was published online on Advanced Energy Materials (2019, DOI: 10.1002/aenm. 201803889).

  Based on the understanding of nanocrystalline/quantum dots-doping semiconductor(Angew. Chem. 2015; Adv. Mater. 2015; Nature Nanotech. 2018; Angew Chem. 2018), the team discovered that the mechanism of switch from nonluminescence to luminescence for several cycles. Controlled viscosity "ink" preparation is then achieved by surface ligand exchange and doping QDS ink in an alkaline water/EG glycol solvent. Furthermore, inkjet printing and patterning of macroscopic doped quantum dots on different substrates (parchpaper, banknotes, flexible substrates such as PET) (macro centimeter, decimeter size device scale) are realized. The patterns of such doped QDs on substrates can be switched by in situ cation exchange to achieve conversion of the disappearance and recovery of luminescent signals, from which a multiple mode anticounterfeiting verification can be provided. Related work entitled "Hydrophilic Doped Quantum Dots "Ink" and Their Inkjet-Printed Patterns for Dual Mode Anti-Counterfeiting by Reversible Cation Exchange Mechanism", is published online on Advanced Functional Materials (DOI: 10.1002/adfm.201808762). Huang Wenyi graduate student and Xu Meng lecturer are the co-first authors of the thesis.

  Based on the precise synthesis of Au@telluride core/shell nanorods, the team realized continuous adjustable visible-near-infrared according to  the narrow band gap characteristics of the shell material and the surface plasmon resonance effect of the Au nanorods. Working with Xie Liming Researcher team (photodetector characterization) of National Center for Nanoscience and Technology, Professor Sarah J. Haigh (high-resolution STEM characterization) at the University of Manchester, UK, and Professor Andrey L. Rogach from the City University of Hong Kong (sponsored by the Overseas Masters’ Program), the team has fabricated Au@HgxCd1-xTe nanorods on graphene photodetector based on the characteristics of carrier mobility. The synthesized device achieves high photoresponsivity (106A/W) from visible to near-infrared wideband (550-1300 nm), which demonstrated its application value in the field of infrared photodetection. Related work was published on Nano Energy (2019, 57, 57-65) with the title "Au@HgxCd1-xTe core@shell nanorods by sequential aqueous exchange for near-infrared photodetectors". Dr. Li Xinyuan is the first author of the thesis.

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