Note: at the end of the paper, there is a brief introduction of the research team and an analysis of the research ideas in this paper
Quantum dots are a kind of semiconductor nanoparticles, whose excitons are confined in three-dimensional space within the same or smaller scale as their exciton Bohr diameter, thus showing different physical properties from the corresponding macroscopic materials. In recent years, the emerging perovskite quantum dots have attracted people's attention for their excellent and unique photoelectric properties, such as the adjustable energy levels in visible light band, high quantum yield, high carrier mobility, etc.; while the traditional lead sulfide quantum dots have high tunability in the near red region due to their energy levels and fluorescence, and also occupy an important position in the field of nano optoelectronic devices. Due to the high complementarity and matching of the photoelectric properties of the two materials, researchers have done a lot of research on their composite system, perovskite lead sulfide heterojunction. However, how to prepare heterojunction quantum dots composed of perovskite quantum dots and lead sulfide quantum dots, and how to control their energy levels and fluorescence properties at the same time, has always been a great challenge.
Recently, Professor Xu Xiangxing of Nanjing Normal University, researcher Liu Xinfeng of national nano science center and Professor Wang Xun of Tsinghua University have developed a method to transform cspbx3 (x = Cl, Br, I) perovskite quantum dots into cspbx3? PBS (x = Cl, Br, I) heterojunction quantum dots. The conversion is carried out at room temperature, and the reaction process can be controlled by reaction time, sulfur source and the ratio of perovskite quantum dots. In particular, the prepared cspbx3? PBS heterojunction quantum dots have visible infrared double emission fluorescence corresponding to cspbx3 quantum dots and PbS quantum dots, and the position of fluorescence emission peak can be adjusted by controlling the size and composition of quantum dots. By using femtosecond transient absorption spectroscopy and transient / steady-state fluorescence spectroscopy, the exciton dynamics in the cspbbr3? PBS heterojunction quantum dots prepared by this synthesis strategy was studied, and the efficient energy transfer from cspbbr3 to PBS in the heterojunction quantum dots was confirmed.
This work provides an effective strategy for the controllable preparation of heterojunctions based on perovskite nanomaterials, which is expected to play an important role in the research of physical properties of such heterojunctions and their applications in the fields of photoelectricity and photovoltaic. This achievement was recently published in J. am. Chem. SOC. The first author is Zhang Xianju, a graduate student of Nanjing Normal University.
Original text (scan or long press QR code, and then go to the original page after identification):
Heterostructural CsPbX3-PbS (X=Cl,Br,I) Quantum Dots with Tunable Vis–NIR Dual Emission
Xianju Zhang, Xianxin Wu, Xiaoyu Liu, Gaoyu Chen, Yongkai Wang, Jianchun Bao, Xiangxing Xu, Xinfeng Liu, Qi Zhang, Kehan Yu, Wei Wei, Jingjing Liu, Jun Xu, Hua Jiang, Peng Wang, Xun Wang
J. Am. Chem. Soc., 2020, 142, 4464-4471, DOI: 10.1021/jacs.9b13681
Analysis of scientific research ideas
Q: How did the idea of the study come about? A: We have accumulated rich experience in the preparation, properties and applications of quantum dots, and have entered the research field of perovskite nano materials earlier. The concept and synthesis of heterojunction quantum dots have been formed for a long time, and people have a certain understanding of their properties. Compared with the heterojunction of non quantum dots, heterojunction quantum dots will introduce the characteristics of quantum dots, which will inevitably bring new properties. In fact, almost all perovskite based optoelectronic devices form heterojunction with the semiconductor in contact with perovskite. Therefore, we naturally associate with the preparation of heterojunction quantum dots based on perovskite. In the selection of material system, the all inorganic perovskite quantum dot is selected because of its good stability and mature synthesis method. The lead sulfide quantum dot is selected because of its ability to expand the energy level regulation of pure perovskite. The lattice parameters and perovskite are also relatively matched. The combination of the two will have a strong application potential in near-infrared photoelectric devices and photovoltaic devices.
Q: What are the challenges in the research? A: We have carried out the controllable synthesis of perovskite heterostructure quantum dots since 2016, and it took us three years to make a breakthrough. The biggest challenge in the research is how to make perovskite quantum dots and lead sulfide quantum dots grow together, because in most cases, during the preparation process, they will form their own nuclei, or they will grow only one layer of the subcrystalline cell scale on each other's surface, or they will generate a mixture of different components and shapes. At last, we use TMS 2S as sulfur source to react with perovskite quantum solution dots at room temperature, which is successful. This work is done by a combination of several subjects, which also enables us to get more support and help when dealing with challenges.
Q: What are the important applications of the research results?? A: The cspbx3? PBS heterojunction quantum dots prepared by this method have good dispersivity in the solvent, and can be easily prepared into thin films or compounded with polymers; their fluorescence characteristics and high-efficiency energy transfer characteristics will make them have great application potential in photoelectric and photovoltaic fields, such as electric driven near-infrared light sources, photodetectors, thin-film solar cells and other devices (including Flexible devices). It can also be used in the synthesis of other heterojunction quantum dots.
Introduction to tutor Xu Xiangxing https://www.x-mol.com/university/factory/184141 Wang Xun http://thuwangxungroup.com/https://www.x-mol.com/university/factory/12037 Liu Xinfeng http://sourcedb.nanoctr.cas.cn/zw/zxrck/201505/t2015007_.html
The copyright of this article belongs to x-mol (x-mol.com), which is not allowed to be reproduced without permission! Welcome readers and friends to share in the circle of friends or Weibo!
Long press the following figure to identify the QR code in the figure, and pay attention to us easily!
Click "read the original" to view all journals in the field of chemistry? Materials