The development of noncontact humidity sensors with high sensitivity, rapid response, and a facile fabrication process is urgently desired for advanced noncontact human–machine interaction (HMI) applications. Here, a flexible and transparent humidity sensor based on MoO3 nanosheets is developed with a low‐cost and easily manufactured process. The designed humidity sensor exhibits ultrahigh sensitivity, fast response, great stability, and high selectivity, exceeding the state‐of‐the‐art humidity sensors. Furthermore, a wearable moisture analysis system is assembled for real‐time monitoring of ambient humidity and human breathing states. Benefiting from the sensitive and rapid response to fingertip humidity, the sensors are successfully applied to both a smart noncontact multistage switch and a novel flexible transparent noncontact screen for smart mobile devices, demonstrating the potential of the MoO3 nanosheets‐based humidity sensors in future HMI systems.

Due to remarkable electronic property, optical transparency and mechanical flexibility, monolayer molybdenum disulfide (MoS2) has been demonstrated to be promising for electronic and optoelectronic devices. To date, the growth of highquality and large-scale monolayer MoS2 has been one of the main challenges for practical applications. Here we present a MoS2-OH bilayer mediated method that can fabricate inch-sized monolayer MoS2 on arbitrary substrates. This approach relies on a layer of hydroxide groups (-OH) that are preferentially attached to the (001) surface of MoS2 to form MoS2-OH bilayer structure for growth of large area of monolayer MoS2 during the growth process. Specifically, the hydroxide layer impedes vertical growth of MoS2 layers along the [001] zone axis, promoting the monolayer growth of MoS2, constrains growth of the MoS2 monolayer only in lateral direction into larger area, and effectively reduces sulfur vacancy and defects according to density functional theory calculations. Finally, the hydroxide groups advantageously prevent the MoS2 from interface oxidation in air, rendering high-quality MoS2 monolayers with carrier mobility up to ~ 30 cm 2 V-1 s-1. Using this approach, inch-sized uniform monolayer MoS2 has been fabricated on the sapphire and mica and high-quality monolayer MoS2 of single crystalline domains exceeding 200 μm has been grown on various substrates including amorphous SiO2 and quartz and crystalline Si, SiC, Si3N4 and graphene This method provides a new opportunity for the monolayer growth of other two-dimensional (2D) transition metal dichalcogenides (TMDs) such as WS2, MoSe2.

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Non-layered 2D ZnSb nanoplates are successfully synthesized to fabricate infrared polarized photodetectors, exhibiting, high responsivity, fast photoresponse speed, great stability, high anisotropic conductivity and linear polarization sensitivity.

Organic photodetectors (OPDs) have attracted great attention because of their advantages including tunable response range, easy processability, and flexibility. Various conjugated polymers have been developed for high-performing OPDs. Herein, a series of tellurophene-based random copolymers containing two typical electron-withdrawing units naphthalene diimide (NDI) and perylene diimide (PDI) are designed and synthesized. Through varying the ratio of PDI/NDI moieties of the analogous polymers, the optophysical properties and film morphology, together with photodetector performances, are systematically tuned. It was demonstrated that the photodetectors based on the polymer with the molar ratio of PDI/NDI units of 70/30 possessed strong photoinduced absorption and favorable morphology via transient absorption spectra and atomic force microscopy studies. As a result, a high responsivity about 19.1 A/W at 600 nm and an excellent detectivity more than 10 Jones ranging from 350 to 600 nm were successfully achieved, which are among the highest values for OPDs and comparable to inorganic counterparts.

Heterostructured ZnS/InP nanowires, composed of single-crystalline ZnS nanowires coated with a layer of InP shell, were synthesized via a one-step chemical vapor deposition process. As-grown heterostructured ZnS/InP nanowires exhibited an ultrahigh I/I ratio of 4.91 × 10, a high photoconductive gain of 1.10 × 10, a high detectivity of 1.65 × 10 Jones and high response speed even in the case of very weak ultraviolet light illumination (1.87 μW cm). The values are much higher than those of previously reported bare ZnS nanowires owing to the formation of core/shell heterostructures. Flexible ultraviolet photodetectors were also fabricated with the heterostructured ZnS/InP nanowires, which showed excellent mechanical flexibility, electrical stability and folding endurance besides excellent photoresponse properties. The results elucidated that the heterostructured ZnS/InP nanowires could find good applications in next generation flexible optoelectronic devices.

A simple self-catalyzed chemical vapor deposition process was conducted to synthesize single-crystalline GaSb nanowires, where Ga droplets were utilized as the catalysts. The as-grown GaSb nanowires exhibited typical p-type semiconductor behavior with the calculated hole mobility of about 0.042 cm 2 V −1 s −1 . The photoresponse properties of the GaSb nanowires were studied by fabricating nanowire photodetectors on both rigid and flexible substrates. The results revealed that the photodetectors exhibited broad spectral response ranging from ultraviolet, visible, to near-infrared region. For the device on rigid substrate, the corresponding responsivity and the detectivity were calculated to be 3.86×10 3 A W −1 and 3.15×10 13 Jones for 500 nm light, and 7.22×10 2 A W −1 and 5.90×10 12 Jones for 808 nm light, respectively, which were the highest value compared with those of other reported Ga 1−x In x As y Sb 1−y structure nanowires. Besides, the flexible photodetectors not only maintained the comparable good photoresponse properties as the rigid one, but also possessed excellent mechanical flexibility and stability. This study could facilitate the understanding on the fundamental characteristics of self-catalyzed grown GaSb nanowires and the design of functional nano-optoelectronic devices based on GaSb nanowires.