Bulk-like molybdenum disulfide (MoS2) thin films were deposited on the surface of p-type Si substrates using dc magnetron sputtering technique and MoS2/Si p-n junctions were formed. The vibrating modes of E12g and A1g were observed from the Raman spectrum of the MoS2 films. The current density versus voltage (J-V) characteristics of the junction were investigated. A typical J-V rectifying effect with a turn-on voltage of 0.2 V was shown. In different voltage range, the electrical transporting of the junction was dominated by diffusion current and recombination current, respectively. Under the light illumination of 15 mW cm−2, the p-n junction exhibited obvious photovoltaic characteristics with a short-circuit current density of 3.2 mA cm−2 and open-circuit voltage of 0.14 V. The fill factor and energy conversion efficiency were 42.4% and 1.3%, respectively. According to the determination of the Fermi-energy level (∼4.65 eV) and energy-band gap (∼1.45 eV) of the MoS2 films by capacitance-voltage curve and ultraviolet-visible transmission spectra, the mechanisms of the electrical and photovoltaic characteristics were discussed in terms of the energy-band structure of the MoS2/Si p-n junctions. The results hold the promise for the integration of MoS2 thin films with commercially available Si-based electronics in high-efficient photovoltaic devices.

Using nanomaterials to develop multimodal systems has generated cutting-edge biomedical functions. Herein, we develop a simple chemical-vapor-deposition method to fabricate graphene-isolated-Au-nanocrystal (GIAN) nanostructures. A thin layer of graphene is precisely deposited on the surfaces of gold nanocrystals to enable unique capabilities. First, as surface-enhanced-Raman-scattering substrates, GIANs quench background fluorescence and reduce photocarbonization or photobleaching of analytes. Second, GIANs can be used for multimodal cell imaging by both Raman scattering and near-infrared (NIR) two-photon luminescence. Third, GIANs provide a platform for loading anticancer drugs such as doxorubicin (DOX) for therapy. Finally, their NIR absorption properties give GIANs photothermal therapeutic capability in combination with chemotherapy. Controlled release of DOX molecules from GIANs is achieved through NIR heating, significantly reducing the possibility of side effects in chemotherapy. The GIANs have high surface areas and stable thin shells, as well as unique optical and photothermal properties, making them promising nanostructures for biomedical applications.

Two‐dimensional‐material‐based self‐driven photodetectors show high sensitivity, fast and broadband response under built‐in electric field in a P–N junction configuration. However, the methods, including doping and multiple transfer processes, for constructing the heterostructures is complex and time‐costing. On the other hand, asymmetric Schottky barrier heights caused by metal electrodes scale, kinds, contact area and thickness can lead to zero‐bias driven photo‐response. In this work, a metal–semiconductor–metal irregular WS2 photodetector with symmetric electrodes are achieved by wet‐transfer. A high zero‐bias photo‐responsivity of 777 mA W−1, a fast response speed of 7.8/37.2 ms, a Ilight/Idark ratio of 104 and a high detectivity of 4.94 × 1011 Jones under 405 nm light are obtained because of a Schottky barrier height difference of ≈50.2 mV through Fermi‐level pinning effect and different contact area. The responsivity at −2 V is stable in the range of 2.23 to 3.45 A W−1 and the empirical factor reaches to 0.99 by the efficient carrier generation process. The WS2 asymmetric Schottky photodetectors outperform most heterostructure based photodiodes. This paper provides a facile route toward self‐powered photodetectors with high performance, easy processing and simple architecture for future applications.

In-plane anisotropic two-dimensional (2D) materials offer great opportunities for developing novel polarization sensitive photodetectors without in conjunction of filters and polarizers. However, owing to low linear dichroism ratio and insufficient...