Two-dimensional (2D) indium selenide, with its low effective mass, high thermal velocity, and exceptional electronic mobility, is a promising semiconductor for surpassing silicon electronics, but grown films have not achieved performance comparable with that of exfoliated micrometer-scale flakes. We report a solid‒liquid‒solid strategy that converts amorphous indium selenide films into pure-phase, high-crystallinity indium selenide wafers by creating an indium-rich liquid interface and maintaining a strict 1:1 stoichiometric ratio of indium to selenium. The as-obtained indium selenide films exhibit exceptional uniformity, a pure phase, and a high crystallinity across an entire ~5-centimeter wafer. Transistor arrays based on the produced indium selenide wafers demonstrate outstanding electronic performance surpassing that of all 2D film-based devices, including an extremely high mobility (averaging as high as 287 square centimeters per volt-second) and a near-Boltzmann-limit subthreshold swing (averaging as low as 67 millivolts per decade) at room temperature.

Lead sulfide (PbS) is a nanomaterial with excellent optical and chemical properties, such as a narrow bandgap (0.37 eV), high thermal damage threshold, and high stability. Obviously, it is appropriate as a saturable absorber (SA) device for ultrafast photonics. However, PbS nanoparticles (NPs) as the SA of ultrashort harmonic mode‐locked pulse still haven't been demonstrated at present. In this paper, the PbS NPs are made into an SA‐device‐based microfiber by optical deposition method and connected in an integrated Erbium‐doped fiber laser. And both characteristics and nonlinear optical properties of PbS NPs have been systemically investigated. A fundamental frequency mode‐locked pulsed laser is proposed, whose central wavelength is 1560 nm, and the pulse width is 1 ps. In addition, high repetition rate operations are achieved, with a maximum repetition rate of 833 MHz. This is the first time that PbS NPs are used to generate 96th‐order harmonic mode‐locking, and the corresponding pulse duration is 987 fs. It is demonstrated that PbS NPs are a kind of SA photonic material with excellent performance. It can improve the communication capacity by applying fiber communication, and it has potential application value even in material processing and optical comb.

Based on fluorinated photoresist, an orthogonal lift-off process was introduced to directly fabricate patterning metallic source and drain contacts on polymeric thin films to obtain the top-contact structure device. Top-contact polymeric thin-film transistors (TFTs) on the wafer using this orthogonal lift-off process exhibited excellent value of electrical characteristics which was as high as 2.56 cm 2 V −1 s −1 in mobility and >10 7 in on/off ratio. Compared with Ref. device which was fabricated by shadow mask, this top-contact polymeric TFTs showed the same mobilities but smaller channel length, and the lower contact resistance. In addition, based on fluorinated photoresist, the top-contact polymeric TFTs backplane with photo-patternable expoxy gate insulating layer was also successfully fabricated on glass. The mobility values of this OTFTs with different channel lengths ranged from 0.25 to 0.74 cm 2 V −1 s −1 with an average of 0.48 ± 0.15 cm 2 V −1 s −1 which can be comparable to the Ref. device with epoxy gate insulator using shadow mask method. It was further proved that the availability of such orthogonal photoresists promised to enable the fabrication of high performance OTFT device based the copolymer with long linear alkyl chains.

Two-dimensional layered metal chalcogenides (LMCs) are widely used in battery anode materials, energy conversion, and semiconductor devices, because of their high energy storage characteristics, high thermoelectric characteristics, and large electron mobility. SnSe2 as a kind of LMC has strong nonlinear optical characteristics. However, its research on dissipative system dynamics as a saturable absorber has not been studied. In this work, we obtained SnSe2 nanosheets using lithium ion intercalation and we reported a passively mode-locked fiber laser with SnSe2 as a saturable absorber to achieve the dissipative soliton in a dissipative system. Due to the high third-order nonlinearity of SnSe2, the evolution of square wave pulses from 2 to 16 ns was obtained in a fiber ring cavity. Through adjusting the polarization state, the evolution phenomenon of soliton rain, the soliton rain phenomenon with a spectrum of dual-wavelengths, and a bound state harmonic phenomenon with a frequency of 313 MHz were obtained. Therefore, the strong nonlinear fiber laser based on SnSe2 provides a good platform for study the pulsation, explosion, rainfall and other phenomena.

Bismuthene, a mono-elemental two-dimensional material with a novel kind of few-layer structure purely consisting of bismuth, has been predicted to have a prominent optical response and enhanced stability in theory. In this paper, few-layer bismuthene is employed as the saturable absorber. The mode-locker is fabricated by dropping bismuthene on a microfiber in a passively mode-locked, Er-doped fiber laser. The single pulse can be obtained at 122.1 mW, with 621.5 fs pulse duration at 1557.5 nm central wavelength, 10.35 nm spectral width and fundamental repetition of 22.74 MHz. Thanks to the outstanding nonlinear effect and semimetal of the bismuthene, dual-pulses, octonary-pulses and fourteen-pulses soliton molecules with tightly and loosely temporal separation can be achieved for the first time, to the best of our knowledge. The preceding indicates that bismuthene will have wide potential in many applications, such as optical fiber communications, optical logical gate, and laser materials processing, etc.

MXenes, recently developed two-dimensional (2D) materials, comprise 2D transition metal carbides, nitrides, and carbonitrides and have variable properties. In particular, accordion-like structures of MXene have highly tunable and tailorable optoelectronic properties, which indicates that they can be applied in broadband optical devices. However, due to the complex synthesis process, the saturable absorber (SA) properties of MXene have not been fully explored and widely applied until now. In this article, the characterization of few-layer MXene nanosheets has been systematically performed. Furthermore, the MXene dispersion is utilized as a SA without any polymer and applied in a compact integrated Er-doped fiber laser at 1.5 mu m to generate a robust, high average power pulse. The proposed robust pulsed laser has minimum pulse width of 1.37 mu s under average output power of 40 mW and the corresponding pulse energy is 305 nJ, which is higher than previous experimental results. Considering the merits of MXene Ti3C2Tx, in the generation of large energy pulses, our work could be a novel method to optimize photonic devices.

Based on standard photolithography, it was demonstrated that an added processing of oxygen plasma treatment to polymeric film was effective to reduce off-current of patterned OTFT device and improve the adhesion between photoresist and polymeric film before spin-coating. And then two procedures were introduced to obtain better performance during the patterned OSC layer. As a result, the procedure of hard-baking photoresist and then dry-etching can prevent oxygen plasma from swelling to the semiconductor film to obtain better performance. Most importantly, the high stability and uniformity OTFT device arrays were fabricated via the modified photolithography processing. Firstly, the transfer curve of OTFT with 5 months later showed any non-degradation compared to the characteristics of the fresh OTFT device. The reason may be that the photoresist on OSC channel can protect OSC from the H2O in air. Secondly, the low threshold voltage shift under positive and negative bias stress test showed low charge trapping in the semiconductor/dielectric interface region. Finally the method was applied to fabricate polymeric OTFTs arrays on the 4-inches wafer with features down to 10m. As a result, it demonstrated the excellent uniformity, which is high mobility of 0.24-0.31cm(2) V-1 s(-1), low threshold voltage shift of -5 to -3V, and ion/off ratio of 10(8)-10(10).

A diazonaphthoquinone (DNQ)-based cross-linkable photo-sensitive cresol novolak resin through acid-catalyzed condensation with melamine molecules is presented as an organic gate insulator (OGI) for the fabrication of poly(3-hexylthiophene) thin-film transistors. This novolak OGI exhibits a remarkably smooth surface of Ra 1.0nm and RMS 0.3nm and shows excellent chemical resistance against common process solvents upon a post exposure bake 150 degrees C. The corresponding metal-insulator-metal diode incorporated with a 200nm thick OGI demonstrates remarkable low leakage current level of 10pA/cm(2) @3MV/cm. Bottom-contact poly(3-hexylthiophene) (P3HT) transistors with novolak OGI on both rigid glass and flexible polyethylene terephthalate (PET) plastic substrates are further demonstrated, suggesting that novolak polymer is a promising candidate for realizing a high performance OGI at low processing temperature.