Interlayer sensitized van der Waals heterojunction photodetector with enhanced performance

Although photodetection based on two-dimensional(2D)van der Waals(vdWs)P-N heterojunction has attracted extensive attention recently,their low responsivity(R)due to the lack of carrier gain mechanism in reverse bias or zero bias operation hinders their applications in advanced photodetection area.Here,a black phosphorus/rhodamine 6G/molybdenum disulfide(BP/R6G/MoS_(2))photodiode with high responsivity at reverse bias or zero bias has been achieved by using interfacial charge transfer of R6G molecules assembled between heterojunction layers.The formed vdWs interface achieves high performance photoresponse by efficiently separating the additional photogenerated electrons and holes generated by R6G molecules.The devices sensitized by the dye molecule R6G exhibit enhanced photodetection performance without sacrificing the photoresponse speed.Among them,the R increased by 14.8-20.4 times,and the specific detectivity(D^(*))increased by 24.9-34.4 times.The strategy based on interlayer assembly of dye molecules proposed here may pave a new way for realizing high-performance photodetection based on 2D vdWs heterojunctions with high responsivity and fast response speed.

Present advances and perspectives of broadband photo-detectors based on emerging 2D-Xenes beyond graphene

As an excellent optical device,photodetectors have many important applications,such as communication technology,display technology,scientific measurement,fire monitoring,aerospace and biomedical research,and ifs of great significance in the research of nanotechnology and optoelectronics.Graphene,as the first two-dimensional(2D)single-element nanomaterial,has the advantages of high carrier mobility,high strength,high light transmittance and excellent thermal conductivity,and ifs widely used in various nano-optical devices.The great success of graphene has led scientists to extensive research on other 2D single-element nanomaterials.Recently,a group of novel 2D single-element nanomaterials have attracted a lot of attention from scientists because of its excellent physical,chemical,electronic,mechanical and optical properties.Furthermore,it has opened a new door for the realization of new and efficient photodetectors.The group of 2D single-element nanomaterials are called 2D-Xenes and used to make high-performance photodetectors.Currently,there are few studies on photodetectors based on 2D-Xenes,but some 2D-Xenes have been applied to photodetectors and reported.Some of these have excellent photodetection performance,such as high photoresponsivity(R),broad spectral response range,fast photoresponse speed and high specific detectivity(D).Based on the novel 2D-Xenes,this review explores the types and preparation methods of 2D-Xenes,and the working mechanisms of 2D-Xenes photodetectors.Finally,the challenges and development trends of 2D-Xenes in the future are discussed.The research of 2D-Xenes is of great significance for the development of high-performance photodetectors in the future,and is expected to be widely used in other nanoelectronics and optical devices.

Thermally tunable microfiber knot resonator with flexible graphene heater

Efficiently tuning the output intensity of an optical device is of vital importance for the establishment of optical interconnects and networks.Thermo-optical modulation is an easily implemented and convenient approach and has been widely employed in photonic devices.In this paper,we proposed a novel thermo-optical modulator based on a microfiber knot resonator(MKR)and graphene heater.Upon applying voltage to graphene,the resonant property of the MKR could be thermally tuned with a maximum phase shift of 2.1π.Intensity modulation shows a fast optical response time thanks to the high thermal conductivity of graphene and the thin microfiber diameter of the MKR.

Graphene/phosphorene nano-heterojunction:facile synthesis, nonlinear optics, and ultrafast photonics applications with enhanced performance

Owing to its thickness-modulated direct energy band gap, relatively strong light–matter interaction, and unique nonlinear optical response at a long wavelength, few-layer black phosphorus, or phosphorene, becomes very attractive in ultrafast photonics applications. Herein, we synthesized a graphene/phosphorene nano-heterojunction using a liquid phase-stripping method. Tiny lattice distortions in graphene and phosphorene suggest the formation of a nano-heterojunction between graphene and phosphorene nanosheets. In addition, we systematically investigate their nonlinear optical responses at different wavelength regimes. Our experiments indicate that the combined advantages of ultrafast relaxation, broadband response in graphene, and the strong light–matter interaction in phosphorene can be combined together by nano-heterojunction. We have further fabricated two-dimensional(2D) nano-heterojunction based optical saturable absorbers and integrated them into an erbium-doped fiber laser to demonstrate the generation of a stable ultrashort pulse down to 148 fs. Our results indicate that a graphene/phosphorene nano-heterojunction can operate as a promising saturable absorber for ultrafast laser systems with ultrahigh pulse energy and ultranarrow pulse duration. We believe this work opens up a new approach to designing 2D heterointerfaces for applications in ultrafast photonics and other research.The fabrication of a 2D nano-heterojunction assembled from stacking different 2D materials, via this facile and scalable growth approach, paves the way for the formation and tuning of new 2D materials with desirable photonic properties and applications.