Organic-inorganic hybrid halide perovskites, such as CH3NHgPbI3, have emerged as an exciting class of materials for solar photovoltaic applications; however, they are currently plagued by insufficient environmental st...Organic-inorganic hybrid halide perovskites, such as CH3NHgPbI3, have emerged as an exciting class of materials for solar photovoltaic applications; however, they are currently plagued by insufficient environmental stability. To solve this issue, all-inorganic halide perovskites have been developed and shown to exhibit significantly improved stability. Here, we report a single-step chemical vapor deposition growth of cesium lead halide （CsPbX3） microcrystals. Optical microscopy studies show that the resulting perovskite crystals predominantly adopt a square-platelet morphology. Powder X-ray diffraction （PXRD） studies of the resulting crystals demonstrate a highly crystalline nature, with CsPbC13, CsPbBr3, and CsPbI3 showing tetragonal, monoclinic, and orthorhombic phases, respectively. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） studies show that the resulting platelets exhibit well-faceted structures with lateral dimensions of the order of 10-50 μm, thickness around 1 μm, and ultra-smooth surface, suggesting the absence of obvious grain boundaries and the single-crystalline nature of the individual microplatelets. Photoluminescence （PL） images and spectroscopic studies show a uniform and intense emission consistent with the expected band edge transition. Additionally, PL images show brighter emission around the edge of the platelets, demonstrating a wave-guiding effect in high-quality crystals. With a well-defined geometry and ultra-smooth surface, the square platelet structure can function as a whispering gallery mode cavity with a quality factor up to 2,863 to support laser emission at room temperature. Finally, we demonstrate that such microplatelets can be readily grown on a variety of substrates, including silicon, graphene, and other two-dimensional materials such as molybdenum disulfide, which can readily allow the construction of heterostructure optoelectronic devices, including a graphene/perovskite/ graphene vertically-stacked photodetector with photoresponsivity 〉 10^5 A/W. The extraordinary optical properties of CsPbX3 platelets, combined with their ability to be grown on diverse materials to form functional heterostructures, can lead to exciting opportunities for broad optoelectronic applications.展开更多
Plate-like single-crystalline BaBi_(4)Ti_(4)O_(15) particles were synthesized by the molten salt synthesis(MSS)method.The effects of sintering temperature,holding time,and NaCl-KCl molten salt content on the phase str...Plate-like single-crystalline BaBi_(4)Ti_(4)O_(15) particles were synthesized by the molten salt synthesis(MSS)method.The effects of sintering temperature,holding time,and NaCl-KCl molten salt content on the phase structure and morphology of plate-like BaBi_(4)-Ti_(4)O_(15) particles were investigated.The results show that plate-like BaBi_(4)Ti_(4)O_(15) particles can be synthesized when the sintering temperature is above 800°C.The size of particles increases with increasing sintering temperature and molten salt content.Largely anisotropic plate-like BaBi_(4)Ti_(4)O_(15) particles with diameter≥10μm and thickness of~0.3μm can be obtained under the optimum process parameters.The crystal structure of BaBi_(4)Ti_(4)O_(15) was determined as A21am by TEM,which should be attributed to the Bi3+and Ba2+diffusing into[TiO6]octahedrons.展开更多
基金Acknowledgements We acknowledge the support from the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering through Award DE-SC0008055. The effort at Hunan University was supported by National Natural Science Foundation of China （No. 61528403）.
文摘Organic-inorganic hybrid halide perovskites, such as CH3NHgPbI3, have emerged as an exciting class of materials for solar photovoltaic applications; however, they are currently plagued by insufficient environmental stability. To solve this issue, all-inorganic halide perovskites have been developed and shown to exhibit significantly improved stability. Here, we report a single-step chemical vapor deposition growth of cesium lead halide （CsPbX3） microcrystals. Optical microscopy studies show that the resulting perovskite crystals predominantly adopt a square-platelet morphology. Powder X-ray diffraction （PXRD） studies of the resulting crystals demonstrate a highly crystalline nature, with CsPbC13, CsPbBr3, and CsPbI3 showing tetragonal, monoclinic, and orthorhombic phases, respectively. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） studies show that the resulting platelets exhibit well-faceted structures with lateral dimensions of the order of 10-50 μm, thickness around 1 μm, and ultra-smooth surface, suggesting the absence of obvious grain boundaries and the single-crystalline nature of the individual microplatelets. Photoluminescence （PL） images and spectroscopic studies show a uniform and intense emission consistent with the expected band edge transition. Additionally, PL images show brighter emission around the edge of the platelets, demonstrating a wave-guiding effect in high-quality crystals. With a well-defined geometry and ultra-smooth surface, the square platelet structure can function as a whispering gallery mode cavity with a quality factor up to 2,863 to support laser emission at room temperature. Finally, we demonstrate that such microplatelets can be readily grown on a variety of substrates, including silicon, graphene, and other two-dimensional materials such as molybdenum disulfide, which can readily allow the construction of heterostructure optoelectronic devices, including a graphene/perovskite/ graphene vertically-stacked photodetector with photoresponsivity 〉 10^5 A/W. The extraordinary optical properties of CsPbX3 platelets, combined with their ability to be grown on diverse materials to form functional heterostructures, can lead to exciting opportunities for broad optoelectronic applications.
基金supported by the China-Poland International Collaboration Fund of National Natural Science Foundation of China(51961135301)the National Natural Science Foundation of China(12074318 and 52072301)+1 种基金the International Cooperation Foundation of Shaanxi Province(2022KW-34)the Undergraduate Innovation and Entrepreneurship Training Program of Shaanxi Province(S202210699511)and the‘111’Project(B20028).
文摘Plate-like single-crystalline BaBi_(4)Ti_(4)O_(15) particles were synthesized by the molten salt synthesis(MSS)method.The effects of sintering temperature,holding time,and NaCl-KCl molten salt content on the phase structure and morphology of plate-like BaBi_(4)-Ti_(4)O_(15) particles were investigated.The results show that plate-like BaBi_(4)Ti_(4)O_(15) particles can be synthesized when the sintering temperature is above 800°C.The size of particles increases with increasing sintering temperature and molten salt content.Largely anisotropic plate-like BaBi_(4)Ti_(4)O_(15) particles with diameter≥10μm and thickness of~0.3μm can be obtained under the optimum process parameters.The crystal structure of BaBi_(4)Ti_(4)O_(15) was determined as A21am by TEM,which should be attributed to the Bi3+and Ba2+diffusing into[TiO6]octahedrons.
