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Solar-blind deep ultraviolet (DUV) photodetectors with high responsivity (R) and fast response speed are crucial for practical applications in astrophysical analysis, environmental pollution monitoring, and communication. Recently, 2D tellurium has emerged as a potential optoelectronic material because of its excellent photoelectric properties. In this study, solar-blind DUV photodetectors are demonstrated based on solution-synthesized and air-stable quasi-2D Te nanosheets (Te NSs). An R of 6.5 × 104 A/W at 261 nm and an external quantum efficiency (EQE) of higher than 2.26 × 106% were obtained, which are highest among most other 2D material-based solar-blind DUV photodetectors. Moreover, the photoelectric performance of the quasi-2D Te-based photodetector exhibited good stability even after ambient exposure for 90 days without any encapsulation. These results indicate that quasi-2D Te NSs provide a viable approach for developing solar-blind DUV photodetectors with ultrahigh R and EQE.

Due to their excellent and tailorable optoelectronic performance, low cost, facile fabrication, and compatibility with flexible substrates, solution-processed inorganic and hybrid photo-active materials have attracted extensive interest for next-generation photodetector applications. This review gives a comprehensive compilation of solution-processed photodetectors. The basic structures of the device and important parameters of photodetectors will be firstly summarized. Then the development of various solution processing technologies containing solution synthesis and liquid phase film-forming processes for the preparation of semiconductor films is described. From the materials science point of view, we give a comprehensive overview about the current status of solution processed semiconductor materials including inorganic and hybrid photo-active materials for the application of photodetectors. Moreover, challenges and future trends in the field of solution-processed photodetectors are proposed.

The functional deficiency between physically separated electronic components makes the up-to-date artificial photo memory devices undergo an intricate preparation and assembly process for the discrete elements, modules and final product. In this research, a multi-functional composite, which consists of conductive nanoparticles with a photothermal conversion effect and a polymeric matrix with memory characteristics, is proposed to realize the sensing and successive memory of optical information in the same material instead of device integration. Nanoparticles in the composite can convert light into heat, and heat can change the irreversible viscous flow of the polymers, which results in changing the distribution distance of conductive nanoparticles in the matrix, as well as the resistance of the composite. Therefore, the composite itself can realize light perception and memory. The composite can mimic multiple basic neuro behaviors. This new way of thinking about the polymer physical properties may open doors for polymers in the electronics area, which may be applied in future flexible and wearable electronics or even artificial intelligence with sensory demands.

Two-dimensional (2D) indium selenide (InSe) has been widely studied for application in transistors and photodetectors, which benefit from its excellent optoelectronic properties. Among the three specific polytypes (γ-, ϵ- and β-phase) of InSe, only the crystal lattice of InSe in β-phase (β-InSe) belongs to a non-symmetry point group of $D_{6h}^4$, which indicates stronger anisotropic transport behavior and potential in the polarized photodetection of β-InSe-based optoelectronic devices. Therefore, we prepare the stable p-type 2D-layered β-InSe via temperature gradient method. The anisotropic Raman, transport and photoresponse properties of β-InSe have been experimentally and theoretically proven, showing that the β-InSe-based device has a ratio of 3.76 for the maximum to minimum dark current at two orthogonal orientations and a high photocurrent anisotropic ratio of 0.70 at 1 V bias voltage, respectively. The appealing anisotropic properties demonstrated in this work clearly identify β-InSe as a competitive candidate for filter-free polarization-sensitive photodetectors.

The flexible electronics technology revolution is driven ever forward by a strong demand for portable, wearable and lightweight electronic products in the market. Flexible lithium-ion batteries (LIBs) have attracted considerable attention because of their excellent electrochemical and mechanical properties. Due to the particular folded structure, high electrical conductivity and excellent flexibility, several emerging two-dimensional (2D) noncarbon nanomaterials such as phosphorene, borophene, MoS2, Ti3C2Tx and V2O5 have been widely applied to flexible LIBs with bright prospects. This review examines the existing literature and recent advances of flexible LIBs based on 2D materials, covering the classifications, synthetic methods and merits of emerging 2D noncarbon nanomaterials. Theoretical research and practical applications of emerging 2D noncarbon nanomaterials as electrode materials for flexible LIBs are reviewed as well. In addition, challenges faced by emerging 2D noncarbon nanomaterials are summarized and prospects of these 2D nanomaterials are given in order to broaden their potential in flexible LIBs.

Nanoengineered Heterostructures In article number 2100503, Zhinan Guo, Han Zhang, Paras N. Prasad, and co‐workers report a nanoengineered heterostructure for the first time demonstration of an nanointerface using an inserted graphene layer between black phosphorus (BP) and InSe which inhibits interlayer recombination and greatly improved photodetection performances. [Image: see text]

Great success in 2D van der Waals (vdW) heterostructures based photodetectors is obtained owing to the unique electronic and optoelectronic properties of 2D materials. Performance of photodetectors based 2D vdW heterojunctions at atomic scale is more sensitive to the nanointerface of the heterojunction than conventional bulk heterojunction. Here, a nanoengineered heterostructure for the first‐time demonstration of a nanointerface using an inserted graphene layer between black phosphorus (BP) and InSe which inhibits interlayer recombination and greatly improves photodetection performances is presented. In addition, a transition of the transport characteristics of the device is induced by graphene, from diffusion motion of minority carriers to drift motion of majority carriers. These two reasons together with an internal photoemission effect make the BP/G/InSe‐based photodetector have ultrahigh specific detectivity at room temperature. The results demonstrate that high‐performance vdW heterostructure photodetectors can be achieved through simple structural manipulation of the heterojunction interface on nanoscale., A nanoscale interface engineering in which few‐layer graphene (G) is inserted into the interlayer of black phosphorus (BP)/InSe, forming a 2D BP/G/InSe van der Waals heterojunction, is introduced. Effective electron transfer from BP to InSe is facilitated by the insertion of G, which induces a better photoresponse performance of the BP/G/InSe device.

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.

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.

Studies of the nonlinear optical phenomena that describe the light-matter interactions in 2D crystalline materials have promoted a diverse range of photonic applications. MXene, as a recently developed new 2D material, has attracted considerable attention because of its graphene-like but highly tunable and tailorable electronic/optical properties. In this study, we systematically characterize the nonlinear optical response of MXene Ti3C2Tx nanosheets over the spectral range of 800 nm to 1800 nm. A large effective nonlinear absorption coefficient (βeff∼-10−21 m2/V2) due to saturable absorption is observed for all of the testing wavelengths. The contribution of saturable absorption is two orders of magnitude higher than other lossy nonlinear absorption processes, and the amplitude of βeff strongly depends on the light bleaching level. A negative nonlinear refractive index (n2∼-10−20 m2/W) with value comparable to that of the intensively studied graphene was demonstrated for the first time. These results demonstrate the efficient broadband light signal manipulating capabilities of Ti3C2Tx, which is only one member of the large MXene family. The capability of an efficient broadband optical switch is strongly confirmed using Ti3C2Tx as saturable absorbers for mode-locking operation at 1066 nm and 1555 nm, respectively. A highly stable femtosecond laser with pulse duration as short as 159 fs in the telecommunication window is readily obtained. Considering the diversity of the MXene family, this study may open a new avenue to advanced photonic devices.