The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber have been studied by using the models of the equivalent twin waveguide soliton coupling,effective refractive...The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber have been studied by using the models of the equivalent twin waveguide soliton coupling,effective refractive index,effective normalized frequency and dispersion management solitons.It is shown that the dispersion in the cladding waveguide of the total internal reflective photonic crystal fiber is a positive dispersion,and the dispersion of its core waveguide is a negative dispersion.The method of the compensated probing laser diffraction by the phase hole induced by the stationary pumping laser in the cladding waveguide enables the average dispersion value of the total internal reflective photonic crystal fiber to be close to zero and the zero dispersion point to shift to the short wavelength region.展开更多
Mixed halide perovskites with the ability to tune bandgaps exhibit attractive applications in tandem solar cells,building integrated photovoltaic and wavelength-tunable light-emitting devices.However,halide demixing u...Mixed halide perovskites with the ability to tune bandgaps exhibit attractive applications in tandem solar cells,building integrated photovoltaic and wavelength-tunable light-emitting devices.However,halide demixing under illumination or in the dark with a charge-carrier injection in both hybrid and inorganic perovskites results in bandgap instability and current-density-voltage(J-V)hysteresis,which can significantly hamper their application.Here,we demonstrate that halide segregation and J-V hysteresis in mixed halide inorganic CsPbIBr_(2)solar cells can be effectively mitigated by introducing an intermediate phase-enhanced Ostwald ripening through the control of the chemical composition in the CsPbIBr_(2)precursor solution.Excess amounts of either PbBr_(2)or CsI are incorporated into originally even molar amounts of PbBr_(2)and CsI precursor solutions.With the PbBr_(2)-excess,we observed an enlarged perovskite grain size,no detectable halide phase segregation at the grain boundaries nor the perovskite/TiO2 interface,an increased minority carrier lifetime,a reduced J-V hysteresis,and an improved solar-cell performance.However,different CsI:PbBr_(2)stoichiometric ratios were found to have different effects on the performance of the perovskite solar cell.The excessive lead phase is reactive with the dimethyl sulfoxide(DMSO)in the precursor solution to form the Pb(I,Br)2·DMSO complex and the quasi-twodimensional(2D)CsPb_(2)(I,Br)5,which are conducive to Ostwald maturation and defect extinction.Finally,the CsPbIBr_(2)solar cell with a PbBr_(2)-excess precursor composition reaches a power conversion efficiency(PCE)of 9.37%(stabilized PCE of 8.48%)and a maximum external quantum efficiency of over 90%.展开更多
文摘The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber have been studied by using the models of the equivalent twin waveguide soliton coupling,effective refractive index,effective normalized frequency and dispersion management solitons.It is shown that the dispersion in the cladding waveguide of the total internal reflective photonic crystal fiber is a positive dispersion,and the dispersion of its core waveguide is a negative dispersion.The method of the compensated probing laser diffraction by the phase hole induced by the stationary pumping laser in the cladding waveguide enables the average dispersion value of the total internal reflective photonic crystal fiber to be close to zero and the zero dispersion point to shift to the short wavelength region.
基金the National Natural Science Foundation of China(51802241 and 91963209)the Fundamental Research Funds for the Central Universities(WUT:2019IVB055 and 2019IVA066)+1 种基金ARC Discovery Grant DP150104483,ARC Centre of Excellence in Exciton Science(CE170100026)the Australian Government through the Australian Renewable Energy Agency(ARENA).
文摘Mixed halide perovskites with the ability to tune bandgaps exhibit attractive applications in tandem solar cells,building integrated photovoltaic and wavelength-tunable light-emitting devices.However,halide demixing under illumination or in the dark with a charge-carrier injection in both hybrid and inorganic perovskites results in bandgap instability and current-density-voltage(J-V)hysteresis,which can significantly hamper their application.Here,we demonstrate that halide segregation and J-V hysteresis in mixed halide inorganic CsPbIBr_(2)solar cells can be effectively mitigated by introducing an intermediate phase-enhanced Ostwald ripening through the control of the chemical composition in the CsPbIBr_(2)precursor solution.Excess amounts of either PbBr_(2)or CsI are incorporated into originally even molar amounts of PbBr_(2)and CsI precursor solutions.With the PbBr_(2)-excess,we observed an enlarged perovskite grain size,no detectable halide phase segregation at the grain boundaries nor the perovskite/TiO2 interface,an increased minority carrier lifetime,a reduced J-V hysteresis,and an improved solar-cell performance.However,different CsI:PbBr_(2)stoichiometric ratios were found to have different effects on the performance of the perovskite solar cell.The excessive lead phase is reactive with the dimethyl sulfoxide(DMSO)in the precursor solution to form the Pb(I,Br)2·DMSO complex and the quasi-twodimensional(2D)CsPb_(2)(I,Br)5,which are conducive to Ostwald maturation and defect extinction.Finally,the CsPbIBr_(2)solar cell with a PbBr_(2)-excess precursor composition reaches a power conversion efficiency(PCE)of 9.37%(stabilized PCE of 8.48%)and a maximum external quantum efficiency of over 90%.
