What is a Quantum Dot?
Quantum dots are semiconductor nanostructures that bind excitons in three spatial directions. Sometimes called "artificial atoms", "superlattices", "superatoms" or "quantum dot atoms", it is a new concept introduced in the 1990s. This constraint can be attributed to the electrostatic potential (generated by external electrodes, doping, strain, and impurities), the interface between two different semiconductor materials (eg, in self-assembled quantum dots), and the surface of a semiconductor (eg, semiconductor nanocrystal ), Or a combination of the three. Quantum dots have a separate quantized energy spectrum. The corresponding wave function is located in the quantum dot in space, but extends over several lattice periods. A quantum dot has a small number (1-100) of an integer number of electrons, holes, or electron hole pairs, that is, the amount of electricity it carries is an integer multiple of the elementary charge.
Quantum dot
- Modern quantum dot technology dates back to the mid-1970s, and it was developed to address the global energy crisis. by
- A quantum dot is an important low-dimensional semiconductor material, and its dimensions in three dimensions are not larger than twice the Bohr radius of its corresponding semiconductor material. Quantum dots are generally spherical or spheroidal, and their diameters are often between 2-20 nm. Common quantum dots are composed of IV, II-VI, IV-VI or III-V elements. Specific examples are silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots. Dots and indium arsenide quantum dots.
- A quantum dot is a nano-scale semiconductor.
- The manufacturing methods of quantum dots can be roughly divided into three categories: chemical solution growth methods, epitaxial growth methods, and electric field confinement methods. These three types of manufacturing methods also correspond to three different kinds of quantum dots.
- Chemical solution growth
- In 1993, for the first time, a scientific research group led by Professor MIT Bawendi synthesized quantum dots of uniform size in an organic solution. [4]
- According to their geometric shapes, quantum dots can be divided into box-shaped quantum dots, spherical quantum dots, tetrahedral quantum dots, cylindrical quantum dots, cubic quantum dots, disc-shaped quantum dots, and external fields (
- (1) Quantum dot
- The unique nature of a quantum dot is based on its own
- Quantum dots are not dots
- The research group of Yu Xuefeng, a researcher of Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, cooperated with Professor Zhu Jianhao of the City University of Hong Kong and Professor Zhang Ye of Shenzhen University, and successfully developed a new type of ultra-small black phosphorus quantum dots and applied it to photothermal treatment of tumor. Related research was recently published as a cover story by German Applied Chemistry. [7]
- Black phosphorus is a black inert allotrope obtained from white phosphorus after high temperature and high pressure. It has a wavelike layered structure similar to but different from the layered structure of graphene sheets, and has a semiconductor gap that graphene does not have. More importantly, its semiconductor bandgap is a direct bandgap, that is, the bottom of the electronic conductive energy band (the conduction band) and the top of the non-conductive energy band (the valence band) are in the same position. This means that black phosphorus and light can be directly coupled. [7]
- The research group cleverly adopted a liquid stripping method combining probe ultrasound and water bath ultrasound to control the preparation of two-dimensional layered black phosphorus quantum dots and obtain monoatomic layer thickness black phosphorus quantum dots with a lateral size of approximately 2.6 nm. By examining the optical properties of this ultra-small black phosphorus quantum dot and its effect on the survival rate of different cell lines, it was found that it exhibits excellent near-infrared optical performance, with a light-to-heat conversion efficiency of 28.4% at 808 nm, and near-infrared Laser irradiation can significantly kill tumor cells, and shows good biocompatibility in a variety of cell lines. [7]
- According to reports, two-dimensional layered ultra-small black phosphorus quantum dots, as another form of two-dimensional material, exhibit unique optical properties. At the same time, phosphorus is an essential element in living organisms, making it useful in biomedical applications. Incomparable advantages, so black phosphorus quantum dots have great potential as high-efficiency photothermal agents for cancer treatment. [7]