Two-dimensional(2D)InSe and WS2 exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low...Two-dimensional(2D)InSe and WS2 exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low hole mobility,while 2D WS2 is on the contrary.We propose a 2D heterostructure composed of their monolayers as a solution to both problems.Our first-principles calculations show that the heterostructure has a type-Ⅱband alignment as expected.Consequently,the bandgap of the heterostructure is reduced to 2.19 eV,which is much smaller than those of the monolayers.The reduction in bandgap leads to a considerable enhancement of the visible-light absorption,such as about fivefold(threefold)increase in comparison to monolayer InSe(WS2)at the wavelength of 490 nm.Meanwhile,the type-Ⅱ band alignment also facilitates the spatial separation of photogenerated electron-hole pairs;i.e.,electrons(holes)reside preferably in the InSe(WS2)layer.As a result,the two layers complement each other in carrier mobilities of the heterostructure:the photogenerated electrons and holes inherit the large mobilities from the InSe and WS2 monolayers,respectively.展开更多
In this paper, a random clique network model to mimic the large clustering coefficient and the modular structure that exist in many real complex networks, such as social networks, artificial networks, and protein inte...In this paper, a random clique network model to mimic the large clustering coefficient and the modular structure that exist in many real complex networks, such as social networks, artificial networks, and protein interaction networks, is introduced by combining the random selection rule of the ErdSs and Rényi （ER） model and the concept of cliques. We find that random clique networks having a small average degree differ from the ER network in that they have a large clustering coefficient and a power law clustering spectrum, while networks having a high average degree have similar properties as the ER model. In addition, we find that the relation between the clustering coefficient and the average degree shows a non-monotonic behavior and that the degree distributions can be fit by multiple Poisson curves; we explain the origin of such novel behaviors and degree distributions.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grants No.51979071,51779073,and 51809073)the Jiangsu Provincial Natural Science Fund for Distinguished Young Scholars(Grant No.BK20180021)the National Ten Thousand Talent Program for Young Top-Notch Talents,and the Six Talent Peaks Project of Jiangsu Province.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404013,11474012,11364030,61622406,61571415,51502283 and 11605003the National Key Research and Development Program of China under Grant No2017YFA0206303the MOST of China,and the 2018 Graduate Research Program of Beijing Technology and Business University
文摘Two-dimensional(2D)InSe and WS2 exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low hole mobility,while 2D WS2 is on the contrary.We propose a 2D heterostructure composed of their monolayers as a solution to both problems.Our first-principles calculations show that the heterostructure has a type-Ⅱband alignment as expected.Consequently,the bandgap of the heterostructure is reduced to 2.19 eV,which is much smaller than those of the monolayers.The reduction in bandgap leads to a considerable enhancement of the visible-light absorption,such as about fivefold(threefold)increase in comparison to monolayer InSe(WS2)at the wavelength of 490 nm.Meanwhile,the type-Ⅱ band alignment also facilitates the spatial separation of photogenerated electron-hole pairs;i.e.,electrons(holes)reside preferably in the InSe(WS2)layer.As a result,the two layers complement each other in carrier mobilities of the heterostructure:the photogenerated electrons and holes inherit the large mobilities from the InSe and WS2 monolayers,respectively.
基金Acknowledgements The authors thank Bin Zhou and Changping Yang for helpful discussions. This work was supported by the Chinese Academy of Sciences, the Open Foundation of the State Key Laboratory of Theoretical Physics （Grant No. Y3KF321CJ1）, and the National Natural Science Foundation of China （Grant No. 10835005）.
文摘In this paper, a random clique network model to mimic the large clustering coefficient and the modular structure that exist in many real complex networks, such as social networks, artificial networks, and protein interaction networks, is introduced by combining the random selection rule of the ErdSs and Rényi （ER） model and the concept of cliques. We find that random clique networks having a small average degree differ from the ER network in that they have a large clustering coefficient and a power law clustering spectrum, while networks having a high average degree have similar properties as the ER model. In addition, we find that the relation between the clustering coefficient and the average degree shows a non-monotonic behavior and that the degree distributions can be fit by multiple Poisson curves; we explain the origin of such novel behaviors and degree distributions.
