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Nangong University develops ultra-thin two-dimensional lead iodide crystals to provide new ideas for solar cells

2019-04-22 来源:转载自第三方
Recently, the Nanjing University of Technology research team has prepared an ultra-thin high-quality two-dimensional lead iodide crystal, and through it to achieve the control of the optical properties of two-dimensional transition metal sulfide materials, and provide a new idea for the manufacture of solar cells, photodetectors.
In recent years, the variety of two-dimensional materials has become increasingly abundant, and the technology for constructing van der Waals heterojunctions has become increasingly mature, laying the foundation for the development of functionalized micro-nano devices based on two-dimensional materials. However, many two-dimensional materials are semi-metals (such as graphene) and insulators (such as boron nitride), and most single-element two-dimensional semiconductors such as silylene, decene, etc. can hardly be obtained from bulk materials, thereby limiting their application in optoelectronic devices. Transition metal sulfides (TMDs), which are two-dimensional semiconductor materials, have attracted the attention of researchers because of their optical band gap and easy-regulated photoelectric properties in the vicinity of visible light. However, a large number of theoretical and experimental results prove that the TMD/TMD heterojunction is mostly Type-II heterojunction, and the function is relatively simple. Although black phosphorus and TMD materials can form different types of heterojunctions, the black phosphorus band is narrower and plays a role in luminescence quenching of TMD. At present, there is still no two-dimensional material capable of multiple regulation of the photoelectric properties of TMDs.
Professor Wang Lin of Nanjing University of Technology developed a layer of lead iodide nanosheets with atomic thickness to overcome the above defects. As a two-dimensional layered material, lead iodide has a large atomic number and has been used for nuclear radiation detection at room temperature for a long time, but atomic-scale thickness of lead iodide is rarely studied. This ultra-thin lead iodide nanosheet, termed a wide-bandgap two-dimensional PbI2 crystal of atomic thickness, is an ultra-thin semiconductor material with a thickness of only a few nanometers. The material is synthesized by a solution method. This method has low requirements on equipment, and is simple, fast, and efficient, and can meet the needs of large-area and high-volume material preparation. The synthesized lead iodide nanosheets have a regular triangular or hexagonal shape with an average size of 6 micrometers, a smooth surface and good optical properties.
Researchers have combined this ultra-thin lead iodide nanosheet with two-dimensional transition metal sulfides, artificially designed, stacked them together to obtain different types of heterojunctions, because the energy levels are arranged differently, so iodine Lead can have different effects on the optical performance of different two-dimensional transition metal sulfides. The energy band structure can effectively improve the luminous efficiency, and is advantageous for fabricating devices such as light-emitting diodes and lasers, which are used in display and illumination, and can be utilized in the fields of photodetectors and photovoltaic devices.
This achievement achieves the control of the optical properties of two-dimensional transition metal sulfide materials by ultra-thin lead iodide. Compared with the traditional silicon-based materials, the results have flexibility and micro-nano characteristics, so they can be applied to In the preparation of flexible and integrated optoelectronic devices, two-dimensional semiconductor heterojunction based on lead iodide nanosheets has broad application prospects in the field of integrated micro-nano-optical devices, for the manufacture of solar cells, photodetectors, etc. and also provides a new idea.
Edited by Suzhou Yacoo Science Co., Ltd.