A heightened understanding of nucleation and growth mechanisms is paramount if effective solution processing of organic-inorganic perovskite thin-films for optoelectronic applications is to be achieved. Many fabri- ca...A heightened understanding of nucleation and growth mechanisms is paramount if effective solution processing of organic-inorganic perovskite thin-films for optoelectronic applications is to be achieved. Many fabri- cation techniques have been utilized previously to develop high-performance perovskite layers but there remains an absence of a unifying model that describes accurately the formation of these materials from solution. The present study provides a thorough analysis of nucleation and growth kinetics underpinning the development of hybrid organic-in- organic perovskite thin-films. Through precise control of the perovskite growth conditions the spacing of heteroge- neous nucleation sites was varied successfully from several hundred nanometers to several hundred microns. The crystalline regions surrounding these nuclei were found to comprise clusters of highly-oriented crystal domains exceed- ing 100 pm in diameter. However, no beneficial correlation was found between the size of these well-oriented grain-clus- ters and the optoelectronic performance. The formation of the perovskite microstructure features characteristics of both classical and non-classical growth mechanisms. The insights into perovskite thin-film growth developed by the present study provide clear implications for the development of future hybrid perovskite microstructures.展开更多
Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which ...Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the lowdensity nucleation and the fast growth of graphene. However,the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation.Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 μm s^-1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional(2 D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2 D materials and thus promote their future applications in the photonics and electronics.展开更多
We propose a novel optical polarizer based on an asymmetric dual-core photonic crystal fiber(PCF) with triangular lattice air-holes.The fiber is designed as that the effective indices of modes in the two cores are mat...We propose a novel optical polarizer based on an asymmetric dual-core photonic crystal fiber(PCF) with triangular lattice air-holes.The fiber is designed as that the effective indices of modes in the two cores are matched at one polarized state but mismatched at another polarized state.As a result,one of the polarization states is coupled to the other core and transferred into a high-order mode.The transmission properties of the polarizer are investigated by the semi-vectorial beam propagation method(SV-BPM).Numerical results demonstrate that a device length of 11.3 mm shows extinction ratio as low as-20 dB with bandwidth as great as 80 nm ranging from 1.51 mm to 1.59 mm.展开更多
基金the financial support from the Australian Renewable Energy Agency (ARENA)the Australian Centre for Advanced Photovoltaics (ACAP)the ARC Centre of Excellence in Exciton Science
文摘A heightened understanding of nucleation and growth mechanisms is paramount if effective solution processing of organic-inorganic perovskite thin-films for optoelectronic applications is to be achieved. Many fabri- cation techniques have been utilized previously to develop high-performance perovskite layers but there remains an absence of a unifying model that describes accurately the formation of these materials from solution. The present study provides a thorough analysis of nucleation and growth kinetics underpinning the development of hybrid organic-in- organic perovskite thin-films. Through precise control of the perovskite growth conditions the spacing of heteroge- neous nucleation sites was varied successfully from several hundred nanometers to several hundred microns. The crystalline regions surrounding these nuclei were found to comprise clusters of highly-oriented crystal domains exceed- ing 100 pm in diameter. However, no beneficial correlation was found between the size of these well-oriented grain-clus- ters and the optoelectronic performance. The formation of the perovskite microstructure features characteristics of both classical and non-classical growth mechanisms. The insights into perovskite thin-film growth developed by the present study provide clear implications for the development of future hybrid perovskite microstructures.
基金supported by the National Natural Science Foundation of China(21673161)the Sino-German Center for Research Promotion(1400)
文摘Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the lowdensity nucleation and the fast growth of graphene. However,the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation.Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 μm s^-1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional(2 D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2 D materials and thus promote their future applications in the photonics and electronics.
基金supported by the National Natural Science Foundation of China (No.10904051)the China Postdoctoral Science Foundation (Nos.20080441070 and 200902505) the Jiangsu Planned Projects for Postdoctoral Research Funds (No.0802018B)
文摘We propose a novel optical polarizer based on an asymmetric dual-core photonic crystal fiber(PCF) with triangular lattice air-holes.The fiber is designed as that the effective indices of modes in the two cores are matched at one polarized state but mismatched at another polarized state.As a result,one of the polarization states is coupled to the other core and transferred into a high-order mode.The transmission properties of the polarizer are investigated by the semi-vectorial beam propagation method(SV-BPM).Numerical results demonstrate that a device length of 11.3 mm shows extinction ratio as low as-20 dB with bandwidth as great as 80 nm ranging from 1.51 mm to 1.59 mm.
