In recent years, the surge in energy demand and the increase in air pollution have forced people to seek new clean renewable energy sources. Solar energy is considered one of the most promising clean renewable energy sources. Solar cells are devices that directly convert solar energy into electrical energy and can efficiently convert and use solar energy. In addition to the current major silicon-based solar cells, exploring new types of high-efficiency and inexpensive solar cells has become a research hotspot in recent years.
In recent years, organic-inorganic hybrid MAPbX3 (X=Cl, Br, and I) perovskite materials have received extensive attention because of their excellent photoelectric properties. Thin-film solar cells based on such perovskite structural materials have frequently broken through in efficiency in a few years, from less than 4% in 2009 to 22.1%. In addition, perovskite materials have great application prospects in lasers, light-emitting diodes, and photoelectric sensors. However, the perovskite solar cell light absorbing layers prepared by various processes have so far been perovskite polycrystalline thin films, and the inevitable grain boundary and surface defects of the polycrystalline thin film lead to carrier mobility. Decline in important parameters such as life and diffusion length. Perovskite bulk crystals have been shown to have lower defect state density, higher carrier mobility, and longer carrier recombination lifetime than polycrystalline films. However, due to the high light absorption coefficient of this type of material itself, the perovskite phase single crystals prepared by the conventional method have too large thickness, which leads to an increase in the probability of carrier recombination and is not suitable for the direct preparation of solar cells and the like.
Researcher of the Hu Jinsong Research Group, a researcher of the Molecular Nanostructure and Nanotechnology Key Laboratory of the Institute of Chemistry, Chinese Academy of Sciences supported by the Chinese Academy of Sciences' Strategic Leading Science and Technology Project and the National Natural Science Foundation of China, had developed a large area of ​​calcium titanium suitable for the preparation of the early stage. The ore-absorption layer can improve its grain size, thereby improving the conversion efficiency of the battery (J. Mater. Chem. A, 2016, 4, 13458); Study of improving the level of the mesoporous layer through rare-earth element doping to improve the battery The efficiency method (Nanoscale, 2016, 8, 16881); and the use of scanning probe microscopy to study the relationship between the perovskite absorber layer microstructure and its properties (ACS Appl. Mater. Interfaces, 2015, 7, 28518; ACS Appl. Mater. Interfaces, 2016, 8, 26002). Recently, researchers have made new advances in the controlled preparation and performance of perovskite single crystal thin films. The researchers have developed a solution phase method that uses the spatial confinement effect to realize the in-situ preparation of a millimeter high-quality organic-inorganic hybrid MAPbX3 (X=Cl, Br, I) perovskite single crystal thin film on a substrate. The thickness of the single crystal film prepared by the method can be adjusted in the range of tens of nanometers to several micrometers, and has no selectivity to the substrate, and can be grown in situ on a substrate such as a flexible substrate and a material with high surface roughness. For the preparation of various devices (Figure 1). This is the first time that a large-area single-crystal perovskite film having a thickness of a hundred nanometers suitable for direct preparation of a solar cell and the like has been reported. Studies have shown that the prepared single crystal thin film has good crystallinity, good contact with the substrate, and has optical and electrical properties equivalent to that of the bulk perovskite single crystal (FIG. 2), to further prepare and study the perovskite single crystal thin film. Solar cells and other single crystal devices have opened up new avenues. This work was published in J. Am. Chem. Soc., 2016, 138, 16196.
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