The development of nonlinear optical materials with strong multiphoton absorption(MPA)is crucial for the design of ultrafast nonlinear optical devices,such as optical limiters and all-optical switchers.In this study,w...The development of nonlinear optical materials with strong multiphoton absorption(MPA)is crucial for the design of ultrafast nonlinear optical devices,such as optical limiters and all-optical switchers.In this study,we present the wavelengthdependent coefficients of two-photon absorption(2PA)and three-photon absorption(3PA)in a Ga S film across a broad range of wavelengths from 540 to 1600 nm.The observed dispersions in the 2PA and 3PA coefficients align well with the widely used two-band approximation model applied to direct bandgap semiconductors.Notably,the Ga S film exhibits exceptional MPA properties with a maximum 2PA coefficient of 19.89 cm/GW at 620 nm and a maximum 3PA coefficient of4.88 cm^(3)/GW2at 1500 nm.The Ga S film surpasses those found in traditional wide-bandgap semiconductors like β-Ga_(2)O_(3),Ga N,Zn O,and Zn S while remaining comparable to monolayer Mo S_(2),Cs Pb Br_(3),and(C_(4)H_(9)NH_(3))_(2)Pb Br_(4) perovskites.By employing a simplified two-energy-level model analysis,our results indicate that these large MPA coefficients are primarily determined by the remarkable absorption cross sections,which are approximately 4.82×10^(-52)·cm^(4)·s·photon^(-1)at 620 nm for 2PAand 8.17×10^(-80)·cm^(6)·s^(2)·photon^(-2)at 1500 nm for 3PA.Our findings demonstrate significant potential for utilizing Ga S films in nonlinear optical applications.展开更多
Heterostructures based on new advanced materials offer a cornerstone for future optoelectronic devices with improved photoelectric performance.Band alignment is crucial for understanding the mechanism of charge carrie...Heterostructures based on new advanced materials offer a cornerstone for future optoelectronic devices with improved photoelectric performance.Band alignment is crucial for understanding the mechanism of charge carrier transportation and interface dynamics in heterostructures.Herein,we grew SnS_(2)/Bi_(2)X_(3)(X=Se,Te)van der Waals heterostructures by combining physical vapor deposition with chemical vapor deposition.The band alignment,measured by high-resolution X-ray photoelectron spectroscopy,suggested the successful design of type-Ⅰ SnS_(2)/Bi_(2)Te_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructures.The SnS_(2)/Bi_(2)X_(3) heterostructure greatly improved the photoelectric response of a photoelectrochemical-type photodetector.The photocurrent densities in the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructure-based devices were more than one order of magnitude higher than those of SnS_(2),Bi_(2)Te_(3),and Bi_(2)Te_(3).The improved photoelectric properties of the SnS_(2)/Bi_(2)X_(3) heterostructures can be explained as follows:(i)the photoexcited electrons and holes are effectively separated in the heterostructures;(ii)the charge-transfer efficiency and carrier density at the interface between the SnS_(2)/Bi_(2)X_(3) heterostructures and the electrolyte are greatly improved;(iii)the formed heterostructures expand the light absorption range.The photoelectric performance was further enhanced by efficient light trapping in the upright SnS_(2).The photoelectric response is higher in the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) heterostructure than in the type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructure due to more efficient charge transportation at the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) heterostructure/electrolyte interface.These results suggest that suitable type-Ⅰ and type-Ⅱ heterostructures can be developed for high-performance photodetectors and other optoelectronic devices.展开更多
Since the pioneering work of Yaghi and co-workers on covalent organic frameworks(COFs) in 2005,multitudinous COFs targeting various applications including gas storage and separation,drug delivery,energy storage,cataly...Since the pioneering work of Yaghi and co-workers on covalent organic frameworks(COFs) in 2005,multitudinous COFs targeting various applications including gas storage and separation,drug delivery,energy storage,catalysis and optoelectronic devices have been developed.However,most of them show uniform pore structures with homogeneous porosity.2D heteropore COFs,a new branch of the COF community,have much less been explored mainly due to their challenging synthesis via conventional co-condensation methods.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12261141662 and 12074311)the 2023 Graduate Education Comprehensive Reform Research and Practice Project(No.ZG2023009)。
文摘The development of nonlinear optical materials with strong multiphoton absorption(MPA)is crucial for the design of ultrafast nonlinear optical devices,such as optical limiters and all-optical switchers.In this study,we present the wavelengthdependent coefficients of two-photon absorption(2PA)and three-photon absorption(3PA)in a Ga S film across a broad range of wavelengths from 540 to 1600 nm.The observed dispersions in the 2PA and 3PA coefficients align well with the widely used two-band approximation model applied to direct bandgap semiconductors.Notably,the Ga S film exhibits exceptional MPA properties with a maximum 2PA coefficient of 19.89 cm/GW at 620 nm and a maximum 3PA coefficient of4.88 cm^(3)/GW2at 1500 nm.The Ga S film surpasses those found in traditional wide-bandgap semiconductors like β-Ga_(2)O_(3),Ga N,Zn O,and Zn S while remaining comparable to monolayer Mo S_(2),Cs Pb Br_(3),and(C_(4)H_(9)NH_(3))_(2)Pb Br_(4) perovskites.By employing a simplified two-energy-level model analysis,our results indicate that these large MPA coefficients are primarily determined by the remarkable absorption cross sections,which are approximately 4.82×10^(-52)·cm^(4)·s·photon^(-1)at 620 nm for 2PAand 8.17×10^(-80)·cm^(6)·s^(2)·photon^(-2)at 1500 nm for 3PA.Our findings demonstrate significant potential for utilizing Ga S films in nonlinear optical applications.
基金supported by the National Natural Science Foundation of China(12074311,11774288,11974279)the Natural Science Foundation of Shaanxi Province(2019JC-25)。
文摘Heterostructures based on new advanced materials offer a cornerstone for future optoelectronic devices with improved photoelectric performance.Band alignment is crucial for understanding the mechanism of charge carrier transportation and interface dynamics in heterostructures.Herein,we grew SnS_(2)/Bi_(2)X_(3)(X=Se,Te)van der Waals heterostructures by combining physical vapor deposition with chemical vapor deposition.The band alignment,measured by high-resolution X-ray photoelectron spectroscopy,suggested the successful design of type-Ⅰ SnS_(2)/Bi_(2)Te_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructures.The SnS_(2)/Bi_(2)X_(3) heterostructure greatly improved the photoelectric response of a photoelectrochemical-type photodetector.The photocurrent densities in the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructure-based devices were more than one order of magnitude higher than those of SnS_(2),Bi_(2)Te_(3),and Bi_(2)Te_(3).The improved photoelectric properties of the SnS_(2)/Bi_(2)X_(3) heterostructures can be explained as follows:(i)the photoexcited electrons and holes are effectively separated in the heterostructures;(ii)the charge-transfer efficiency and carrier density at the interface between the SnS_(2)/Bi_(2)X_(3) heterostructures and the electrolyte are greatly improved;(iii)the formed heterostructures expand the light absorption range.The photoelectric performance was further enhanced by efficient light trapping in the upright SnS_(2).The photoelectric response is higher in the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) heterostructure than in the type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructure due to more efficient charge transportation at the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) heterostructure/electrolyte interface.These results suggest that suitable type-Ⅰ and type-Ⅱ heterostructures can be developed for high-performance photodetectors and other optoelectronic devices.
文摘Since the pioneering work of Yaghi and co-workers on covalent organic frameworks(COFs) in 2005,multitudinous COFs targeting various applications including gas storage and separation,drug delivery,energy storage,catalysis and optoelectronic devices have been developed.However,most of them show uniform pore structures with homogeneous porosity.2D heteropore COFs,a new branch of the COF community,have much less been explored mainly due to their challenging synthesis via conventional co-condensation methods.
