Flexible optoelectronic devices attract considerable attention due to their prominent role in creating novel wearable apparatus for bionics, robotics, health care, and so forth. Although bulk single-crystalline perovskite-based materials are well-recognized for the high photoelectric conversion efficiency than the polycrystalline ones, their stiff and brittle nature unfortunately prohibits their application for flexible devices. Here, we introduce ultrathin single-crystalline perovskite film as the active layer and demonstrate a high-performance flexible photodetector with prevailing bending reliability. With a muchreduced thickness of 20 nm, the photodetector made of this ultrathin film can achieve a significantly increased responsivity as 5600A/W, 2 orders of magnitude higher than that of recently reported flexible perovskite photodetectors. The demonstrated 0.2 MHz 3 dB bandwidth further paves the way for high-speed photodetection. Notably, all its optoelectronic characteristics resume after being bent over thousands of times. These results manifest the great potential of single-crystalline perovskite ultrathin films for developing wearable and flexible optoelectronic devices.

No abstract

A novel magnetic responsive Ni-based metal–organic framework material was developed to efficiently separate and immobilize thermal enzymes with high catalytic performance.

CO2foam is stabilized using by-product fly ash and recyclable iron oxide nanoparticles.

No abstract

Most polarization-sensitive photodetectors detect either linearly polarized (LP) or circularly polarized (CP) light. Here, we experimentally demonstrate a multiple-polarization photodetector based on a hybrid organic–inorganic perovskite (HOIP) metasurface, which is sensitive to both LP and CP light simultaneously. The perovskite metasurface is composed of a HOIP antenna array on a single-crystal HOIP film. Owing to the antenna anisotropy, the absorption of linearly polarized light at the metasurface depends on the polarization angle; also, due to the mirror asymmetry of the antenna elements, the metasurface is also sensitive to different circular polarizations. Polarization-dependent photocurrent responses to both LP and CP light are detected. Our results highlight the potential of perovskite metasurfaces for integrated photoelectric applications.

The miniaturization and integration of optoelectronic devices require progressive size reduction of active layers, resulting in less optical absorption and lower quantum efficiency. In this work, we demonstrate that introducing a metasurface made of hybrid organic−inorganic perovskite (HOIP) can significantly enhance broadband absorption and improve photonto-electron conversion, which roots from exciting Mie resonances together with suppressing optical transmission. On the basis of the HOIP metasurface, a broadband photodetector has been fabricated where photocurrent boosts more than 10 times in the frequency ranging from ultraviolet to visible. The device response time is less than 5.1 μs at wavelengths 380, 532, and 710 nm, and the relevant 3 dB bandwidth is over 0.26 MHz. Moreover, this photodetector has been applied as a signal receiver for transmitting 2D color images in broadband optical communication. These results accentuate the practical applications of HOIP metasurfaces in novel optoelectronic devices for broadband optical communication.

Understanding and controlling the growth morphology of two-dimensional crystals of transition metal dichalcogenides (TMDs) is essential in developing high-quality crystalline material for spintronics, valleytronics, electronics, and optics. Here we report our studies on the evolution of crystallite morphology of MoS2 observed in chemical vapor deposition. It is shown that as time goes on, the growth morphology of MoS2 flakes undergoes a transition from a triangle to a star shape, then back to a triangle, and finally to a bulgy irregular morphology. By tuning the temperature of the element sources, the atomic ratio of S and Mo on the growing interface can be adjusted. The variation of the S/Mo ratio affects the edge diffusion length and nucleation behavior on the edge of crystallite, leading to different growth morphologies. Our observations provide clues on how to engineer the morphology and control the quality of TMD crystalline sheets.