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With the unusual luminescence and photoconductive characteristics, the CsPbI3 perovskite has attracted a lot of attention in the field of material synthesis and device fabrication. The general synthesis methods of CsPbI3 are through the organic solvent spin-coating and heating. To avoid the toxic organic solvent, herein we reported the organic solvent-free synthesis method. The precursors PbI2 and CsI were solved in aqueous solution and heated to form the CsPbI3 perovskite. It is found that the Na2S2O3 as a reaction additive could enhance the CsPbI3 crystal quality and the synthesis temperature could be lowered down to 80 °C. The content of Pb2+ was increased by combination with S2O32− in Na2S2O3 aqueous solution. The photoluminescence (PL) spectra showed the PL of CsPbI3 perovskite can disappear/recover through absorbing/removing to moisture, respectively. By integrating the CsPbI3 film to the blue diode, we obtained an LED device. Our method provides an innovative strategy to prepare CsPbI3 perovskites in aqueous solution. We reported water mediated synthesis of phase-stable red-emitting CsPbI3 nanocrystals at the reaction temperature as low as 80 °C with the introduced Na2S2O3 additive. The photoluminescence (PL) spectra with could be fully recovered after continuous cycles of moisture absorption and removal. The temperature-dependence PL spectra demonstrated that the CsPbI3 prepared in the presence of Na2S2O3 exhibited the better PL properties and crystal quality compared with that in the absence of Na2S2O3.

Spectrally selective narrowband Si photodetection is critical for near-infrared (NIR) medical imaging, optical communication, light detection and autonomous mobiles. For conventional inorganic semiconductors such as silicon with broadband absorption from visible until 1.1 µm, it remains challenging to achieve narrowband photodetection without integrating optical filters. We demonstrate the very first narrowest NIR silicon photodetectors without any bandpass filter, reaching the full-width-at-half-maximum of only 26 nm at 912 nm. The narrowband response is inherently attributed to the resonant enhancement effect of optical microcavities formed by patterned Si nanograting combined with the organic D18:Y6 blend film. The Conductive-Atomic Force Microscope (C-AFM), Kelvin Probe Force Microscope (KPFM) and transient absorption (TA) spectroscopy characterization indicate effective charge transfer between Si and organic layers, significantly contributing to ultrafast photoresponse of 74 \(\mu s\). Therefore, this design concept opens up the new possibility of developing filter-less and effective low-cost NIR detection, enabling entirely new configurations of optical imaging devices with narrowband tunability for telecommunications and imaging applications.

Monolayer tungsten disulfide (WS2) with a direct band gap of ca. 2.0 eV and stable properties has been a hotspot in two-dimensional (2D) nanoelectronics and optoelectronics. However, it remains challenging to successfully prepare monolayer WS2. In this paper, we report the chemical vapor deposition (CVD) growth behavior of hexagonal WS2 monolayers by using WS2 powders and sodium triosulfate (Na2S2O3) as precursors. We observed the Na2S2O3 has a significant effect on the WS2 triangular and leaf-like shapes. In addition, based on proposed S-termination and W-termination theory, the growth mechanisms for different shapes of WS2 were discussed.

Two-dimensional (2D) tungsten disulfide (WS2) has inspired great efforts in optoelectronics, such as in solar cells, light-emitting diodes, and photodetectors. However, chemical vapor deposition (CVD) grown 2D WS2 domains with the coexistence of a discontinuous single layer and multilayers are still not suitable for the fabrication of photodetectors on a large scale. An emerging field in the integration of organic materials with 2D materials offers the advantages of molecular diversity and flexibility to provide an exciting aspect on high-performance device applications. Herein, we fabricated a photodetector based on a 2D-WS2/organic semiconductor materials (mixture of the (Poly-(N,N′-bis-4-butylphenyl-N,N′-bisphenyl) benzidine and Phenyl-C61-butyric acid methyl ester (Poly-TPD/PCBM)) heterojunction. The application of Poly-TPD/PCBM organic blend film enhanced light absorption, electrically connected the isolated WS2 domains, and promoted the separation of electron-hole pairs. The generated exciton could sufficiently diffuse to the interface of the WS2 and the organic blend layers for efficient charge separation, where Poly-TPD was favorable for hole carrier transport and PCBM for electron transport to their respective electrodes. We show that the photodetector exhibited high responsivity, detectivity, and an on/off ratio of 0.1 A/W, 1.1 × 1011 Jones, and 100, respectively. In addition, the photodetector showed a broad spectral response from 500 nm to 750 nm, with a peak external quantum efficiency (EQE) of 8%. Our work offers a facile solution-coating process combined with a CVD technique to prepare an inorganic/organic heterojunction photodetector with high performance on silicon substrate.

Monolayer tungsten disulfide (WS

Photodetectors (PD) with high detectivity, high quantum efficiency and fast response are fundamental units to achieve sensors, imagers, and many others functional optoelectronics. Here we demonstrate high performance vertical stacked 2D MoS2/CuPc heterojunction based photodetectors with high sensitivity, high external quantum efficiency and ultrafast response time. The functional p-type organic thin film of CuPc was thermally evaporated on n-type two-dimension (2D) MoS2 monolayer to create an ideal type II heterojunction interface, where ultrafast charge transfer (CT) occur in 16 ps, followed by effective exciton separation and charge collection. As a result, photoresponse time as fast as 436 μs has been obtained for 2D MoS2/CuPc PDs, as well as a profound responsivity of 3.0 × 10 3 A/W and a detectivity of 2.0 × 1010 Jones with a peak external quantum efficiency (EQE) of 483%. This work suggests a feasible route to develop ultrasensitive visible light photodetector by 2D materials.

Monolayer tungsten disulfide (2D WS2) films have attracted tremendous interest due to their unique electronic and optoelectronic properties. However, the controlled growth of monolayer WS2 is still challenging. In this paper, we report a novel method to grow WS2 through chemical vapor deposition (CVD) with ZnO crystalline whisker as a growth promoter, where partially evaporated WS2 reacts with ZnO to form ZnWO4 by-product. As a result, a depletion region of W atoms and S-rich region is formed which is favorable for subsequent monolayer growth of WS2, selectively positioned on the silicon oxide substrate after the CVD growth.

Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious: large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.

This paper presents a new-developed in situ gas-tight pore water sampler for deep-sea sediments,particularly introducing its configuration,feature and working principle.Marine tests and laboratory simulations showed that the sampler was able to be employed to sample pore water of the seafloor sediments with thicknesses of 3～5.5 m,at water depths between 500 and 4 200 m under the sea,and can simultaneously obtain 11 bottles of pore water,each of which is more than 100 mL at volume.