Infrared light detection and sensing is deeply embedded in modern technology and human society and its development has always been benefitting from the discovery of various photoelectric materials. The rise of two-dimensional materials, thanks to their distinct electronic structures, extreme dimensional confinement and strong light–matter interactions, provides a material platform for next-generation infrared photodetection. Ideal infrared detectors should have fast respond, high sensitivity and air-stability, which are rare to meet at the same time in one two-dimensional material. Herein we demonstrate an infrared photodetector based on two-dimensional Bi2O2Se crystal, whose main characteristics are outstanding in the whole two-dimensional family: high sensitivity of 65 AW−1 at 1200 nm and ultrafast photoresponse of ~1 ps at room temperature, implying an intrinsic material-limited bandwidth up to 500 GHz. Such great performance is attributed to the suitable electronic bandgap and high carrier mobility of two-dimensional oxyselenide.

26 expanded the application regimes of optical fibre 1-12 . The emergence of graphene excites new 27 opportunities by combining with PCF, allowing for electrical tunability, broadband optical 28 response and all-fibre integration ability 13-18 . However, the previous demonstrations are typically 29 limited to the sample level of micron size, far behind the requirement of real applications for the 30 metre-scale material level. Here, we demonstrate a new hybrid material of graphene photonic 31 crystal fibre (Gr-PCF) with length up to half a metre by chemical vapour deposition method. The 32 Gr-PCF shows strong light-matter interaction with ~8 dB⋅cm -1 attenuation. In addition, the 33 Gr-PCF-based electro-optic modulator demonstrates broadband response (1150 -1600 nm) and 34 large modulation depth (~20 dB⋅cm -1 at 1550 nm) under low gate voltage of ~2 volts. Our results 35 could enable industrial-level graphene applications based on the Gr-PCF, and suggest an infusive 36 platform of two-dimensional material-PCF. 37Graphene is a promising material in photonic and optoelectronic applications due to its superior 38 properties of high carrier mobility, broadband optical response and facile electrical tunability originating 39 from its unique linear dispersion of massless Dirac fermions [19][20][21][22][23][24][25][26][27][28] . Although the light-matter interaction in 40 graphene normalized by its atomic thickness (0.34 nm) is quite strong, the measurable interaction is in 41 fact quite weak (only ~2.3% light absorption) 29 . To greatly enhance light-graphene interaction, many 42 efforts have been devoted to combine graphene flakes with well-designed optical structures, such as 43 gratings, waveguides and microcavities 30-34 , however, all those hybrid structures have still stayed at 44 sample level of micron size, rather than material level of metre size, which limits their massive 45 applications. Therefore, there exists great demand to develop new methods for massive production on 46 graphene-based optical structures for material-level applications. 47Optical fibre provides the highest-quality optical waveguide for information communication and 48 photon manipulation, and it has been massively manufactured at kilometre length scale. PCF represents 49 the most important advance of optical fibre in the last twenty years and possesses extremely rich 50 functions beyond traditional optical fibre in the exciting applications of endlessly single-mode fibres, 51 supercontinuum lasers, frequency combs, optical soliton propagation, high-power pulse delivery and so 52 on 1-7 . Especially, PCF with ingenious porous structure opens up the hard-won opportunity of filling 53 various materials, ranging from gases, liquids, solids to liquid crystals, to expand its great new 54 3 / 14 functionalities in mode-locked fibre lasers, laser frequency conversion, surface plasmon generation, 55 stimulated Raman scattering and in-fibre thermal-or electro-optic devices 8-15 . The rise of 56 two-dimensional (2D) graphene naturally excites the ...

Photocarrier generation in a material, transportation to the material surface, and collection at the electrode interface are of paramount importance in any optoelectronic and photovoltaic device. In the last collection process, ideal performance comprises ultrafast charge collection to enhance current conversion efficiency and broadband collection to enhance energy conversion efficiency. Here, for the first time, we demonstrate ultrafast broadband charge collection achieved simultaneously at the clean graphene/organic–inorganic halide perovskite interface. The clean interface is realized by directly growing perovskite on graphene surface without polymer contamination. The tunable two-color pump–probe spectroscopy, time-resolved photoluminescence spectroscopy, and time-dependent density functional theory all reveal that the clean-interfacial graphene collects band-edge photocarriers of perovskite in an ultrashort time of ∼100 fs, with a current collection efficiency close to 99%. In addition, graphene can extract deep-band hot carriers of perovskite within only ∼50 fs, several orders faster than hot carrier relaxation and cooling in perovskite itself, due to the unique Dirac linear band structure of graphene, indicating a potential high energy conversion efficiency exceeding the Shockley–Queisser limit. Adding other graphene superiority of good transparency, high carrier mobility, and extreme flexibility, clean-interfacial graphene provides an ideal charge collection layer and electrode candidate for future optoelectronic and photovoltaic applications in two dimensions.

Zhang and co-workers developed a rational approach to growing a new family of semiconducting SWNTs: (n, n À 1) carbon nanotubes. Combined with catalyst design, both large-diameter (>2 nm) (n, n À 1) SWNTs and single-chirality (10, 9) SWNTs with abundances of 88% and >80%, respectively, were successfully realized. This strategy opens up a new route for the growth of SWNT families beyond catalyst design.