Evolution mechanism of Weibo top news competition

In a certain period,some news will compete for the top news to gain the most attention and influence,and more news will be submerged in the ocean of news and become mediocre.This article deeply studies the evolution process and competition mechanism of the dissemination of Weibo news.In this paper,we innovatively propose a pre-processing scheme for traditional small-world networks and scale-free networks and divide nodes into three roles:fans,passersby,and anti-fans.The competition mechanism of Weibo top news is defined from the aspects of node role and node aggregation degree.A network evolution model is established based on the competition mechanism.The propagation characteristics of the network evolution model are deeply analyzed,and simulation experiments are performed on the small-world network and the scale-free network.Finally,the validity and rationality of the new model are verified through comparative experiments,and a feasible scheme for the propagation of top news on Weibo is given.

Organic near-infrared photodetectors with photoconductivityenhanced performance

Organic near-infrared(NIR)photodetectors with essential applications in medical diagnostics,night vision,remote sensing,and optical communications have attracted intensive research interest.Compared with most conventional inorganic counterparts,organic semiconductors usually have higher absorption coefficients,and their thin active layer could be sufficient to absorb most incident light for effective photogeneration.However,due to the relatively poor charge mobility of organic materials,it remains challenging to inhibit the photogenerated exciton recombination and effectively extract carriers to their respective electrodes.Herein,this challenge was addressed by increasing matrix conductivities of a ternary active layer(D–A–D structure NIR absorber[2TT-oC6B]:poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidin[PolyTPD]:[6,6]-phenyl-C61-butyric acid methyl ester[PCBM]=1:1:1)upon in situ incident light illumination,significantly accelerating charge transport through percolated interpenetrating paths.The greatly enhanced photoconductivity under illumination is intrinsically related to the unique donor–acceptor molecular structures of PolyTPD and 2TT-oC6B,whereas stable intermolecular interaction has been verified by systematic molecular dynamics simulation.In addition,an ultrafast charge transfer time of 0.56 ps from the NIR aggregation-induced luminogens of 2TT-oC6B absorber to PolyTPD and PCBM measured by femtosecond transient absorption spectroscopy is beneficial for effective exciton dissociation.The solution-processed organic NIR photodetector exhibits a fast response time of 83μs and a linear dynamic range value of 111 dB under illumination of 830 nm.Therefore,our work has opened up a pioneering window to enhance photoconductivity through in situ photoirradiation and benefit NIR photodetectors as well as other optoelectronic devices.

CsPbBr_3 perovskite quantum dots: saturable absorption properties and passively Q-switched visible lasers

This work presents the saturable absorption(SA) properties of CsPbBr_3 perovskite quantum dots(QDs). The perovskite QDs show excellent SA performance with a nonlinear absorption coefficient of-35 × 10^(-2) cm∕GW and a figure of merit of 3.7 × 10^(-14) esu cm. Further, their use as saturable absorbers in a passively Q-switched visible solid-state laser for the generation of soliton pulses is demonstrated. These results demonstrate thepotential for the perovskite QDs to act as saturable absorbers.

Ultraviolet lasing behavior in ZnO optical microcavities

Zinc oxide(ZnO)optical microcavity modulated UV lasers have been attracting a wide range of research interests.As one of the most important materials in developing high quality microcavity and efficient UV evisible optoelectronic devices due to its wide band gap(3.37 eV)and large exciton binding energy(~60 meV).In this review,we summarized the latest development of ZnO optical cavity based microlasers,mainly including Fabry-Perot mode lasers and whispering gallery mode lasers.The synthesis and optical studies of ZnO optical microcavities with different morphologies were discussed in detail.Finally,we also consider that the research focus in the near future would include new nanotechnology and physical effects,such as nano/micro fabrication,surface plasmon enhancement,and quantum dot coupling,which may result in new and interesting physical phenomena.