In this paper, the resistive switching characteristics in a Cu/HfO(2):Cu/Pt sandwiched structure is investigated for multilevel non-volatile memory applications. The device shows excellent resistive switching performance, including good endurance, long retention time, fast operation speed and a large storage window (R(OFF)/R(ON)>10(7)). Based on the temperature-dependent test results, the formation of Cu conducting filaments is believed to be the reason for the resistance switching from the OFF state to the ON state. By integrating the resistive switching mechanism study and the device fabrication, different resistance values are achieved using different compliance currents in the program process. These resistance values can be easily distinguished in a large temperature range, and can be maintained over 10 years by extrapolating retention data at room temperature. The integrated experiment and mechanism studies set up the foundation for the development of high-performance multilevel RRAM.

Cation-based resistive switching (RS) devices, dominated by conductive filaments (CF) formation/dissolution, are widely considered for the ultrahigh density nonvolatile memory application. However, the current-retention dilemma that the CF stability deteriorates greatly with decreasing compliance current makes it hard to decrease operating current for memory application and increase driving current for selector application. By centralizing/decentralizing the CF distribution, this current-retention dilemma of cation-based RS devices is broken for the first time. Utilizing the graphene impermeability, the cation injecting path to the RS layer can be well modulated by structure-defective graphene, leading to control of the CF quantity and size. By graphene defect engineering, a low operating current (≈1 µA) memory and a high driving current (≈1 mA) selector are successfully realized in the same material system. Based on systematically materials analysis, the diameter of CF, modulated by graphene defect size, is the major factor for CF stability. Breakthrough in addressing the current-retention dilemma will instruct the future implementation of high-density 3D integration of RS memory immune to crosstalk issues.

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Graphene-Si Schottky junction solar cells are promising candidates for high-efficiency, low-cost photovoltaic applications. However, their performance enhancement is restricted by strong carrier recombination and relative low barrier height. Here, we demonstrated the successful construction of high-efficiency graphene-planar Si solar cells via modification of the Si surface with a molecule monolayer as well as tuning the interface band alignment with an organic electron blocking layer.Methylated Si showed the capability to effectively suppress the surface carrier recombination, leading to a remarkable improvement of device efficiency. The recombination was further reduced by inserting a thin P3HT organic layer; the unique band alignment could prevent electron transfer from n-Si to the graphene anode so as to minimize the current leakage. These methods, along with careful control of the graphene doping level and layer number, gave rise to a power conversion efficiency (PCE) as high as 10.56%. The scalability of the devices was further investigated by studying the device area dependent photovoltaic performance.

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This paper introduces the Flexible Global Ocean‐Atmosphere‐Land System Model: Grid‐Point Version 3 (FGOALS‐g3) and evaluates its basic performance based on some of its participation in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) experiments. Our results show that many significant improvements have been achieved by FGOALS‐g3 in terms of climatological mean states, variabilities, and long‐term trends. For example, FGOALS‐g3 has a small (−0.015°C/100 yr) climate drift in 700‐yr preindustrial control (piControl) runs and smaller biases in climatological mean variables, such as the land/sea surface temperatures (SSTs) and seasonal soil moisture cycle, compared with its previous version FGOALS‐g2 during the historical period. The characteristics of climate variabilities, for example, Madden‐Julian oscillation (MJO) eastward/westward propagation ratios, spatial patterns of interannual variability of tropical SST anomalies, and relationship between the East Asian Summer Monsoon and El Niño–Southern Oscillation (ENSO), are well captured by FGOALS‐g3. In particular, the cooling trend of globally averaged surface temperature during 1940–1970, which is a challenge for most CMIP3 and CMIP5 models, is well reproduced by FGOALS‐g3 in historical runs. In addition to the external forcing factors recommended by CMIP6, anthropogenic groundwater forcing from 1965 to 2014 was incorporated into the FGOALS‐g3 historical runs.

The annealing effects on Langmuir-Blodgett (LB) films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (abbreviated as octadecyl-TCNQ) have been investigated by atomic force microscopy (AFM) and ultravioletvisible (UV-vis) and infrared (IR) spectroscopies. An AFM image of a one-layer LB film of octadecyl-TCNQ scanned at room temperature shows that the film consists of numerous platelike microcrystal domains. A periodic structure of octadecyl-TCNQ molecules with a period of 0.85 nm can be observed inside these domains. After the annealing, cooling down the film from 130 to 30°C, some of these domains lie on top of one another, keeping their original morphology. The rest seem to melt into a globular bulk sample. In the case of an 11-layer film, it can be seen from its AFM images that a number of domains with smaller size cover the substrate and that they completely melt after the annealing cycle. The UV-vis spectra of the oneand 11-layer films measured before and after the annealing show that the stacked structure of the TCNQ chromophore recovers partially for the one-layer film, but it recovers little for the 11-layer film. The IR measurements of the one-, three-, seven-, and 11-layer LB films before and after the annealing reveal that the subcell packing of the hydrocarbon chain changes due to the cyclic temperature treatment up to 130°C. The present study also demonstrates that the annealing effects on the LB films of octadecyl-TCNQ are largely different from those on LB films of simple amphiphilic compounds such as fatty acids.

1-(5-(Anthracen-9-yl)-3-(4-methoxyphenyl)-4,5-dihydropyrazol-1-yl)ethanone was synthesized and crystallized to provide three types of crystals with different fluorescent colors and host−guest structures. Crystal structure analysis reveals that this compound possesses twisted π-conjugated structure and different degrees of distortion depending on guest molecules in the three crystal structures. The anthracene fluorophore stacking modes are regulated from monomer arrangement to face-to-face πstacked arrangement by means of the entrapment of organic acid molecules in the lattice. The vibrational spectroscopy, thermal behaviors, diffuse reflectance absorption spectroscopy, solid-state fluorescence properties, and fluorescence quantum yields and lifetimes of the three types of crystals were investigated. Such properties are closely related to the fluorophore stacking modes and intermolecular electronic interactions in crystals. The π-stacked geometries of anthracene fluorophores are responsible for the red-shifted emissions and longer fluorescence lifetimes. It indicates that the optical properties of organic materials could be modulated by entrapping different guest molecules in lattice.