Single-frequency erbium-doped fiber laser based on self-injection feedback.

In this paper, a single-frequency erbium-doped fiber laser based on self-injection feedback is reported, which uses a high-reflectivity broadband fiber Bragg grating, an ordinary commercial high-doped erbium fiber and a low-reflectivity broadband fiber Bragg grating to form the main resonant cavity, and a stable narrow linewidth single-frequency laser output is achieved by connecting a single-mode fiber and a low reflectivity narrowband fiber Bragg grating to form self-injection feedback. Then, a saturated double-pass erbium-doped fiber amplifier and a saturable absorber were added to the self-injection optical path, which well suppressed the relative intensity noise and phase noise and the relaxation oscillation intensity was well suppressed by about 18.08 dB, and the phase noise was 36.

Regional differences and convergence of green innovation efficiency in China.

Green innovation facilitates high-quality economic development and ecological environmental protection. Herein, the minimum distance to strong efficient frontier (MinDS) model was used to measure green innovation efficiencies (GIEs) of 30 Chinese provinces over a period of 21 years (2000-2020). Gini coefficient decomposition and kernel density estimation methods were used to analyze the regional differences of GIE.

Inhibition of Phase Segregation in Cesium Lead Mixed-Halide Perovskites by B-Site Doping.

The emergence of all-inorganic halide perovskites has shown great potential in photovoltaic and optoelectronic devices. However, the photo-induced phase segregation in lead mixed-halide perovskites has severely limited their application. Herein, by real-time monitoring the photoluminescence (PL) spectra of metal mixed-halide perovskites under light irradiation, we found that the photo-induced phase transition can be significantly inhibited by B-site doping.

Controlled growth and ion intercalation mechanism of monocrystalline niobium pentoxide nanotubes for advanced rechargeable aluminum-ion batteries.

Rechargeable aluminum-ion batteries (RAIBs) have attracted increasing attention owing to their high theoretical volumetric capacity, high resource abundance, and good safety performance. However, the existing RAIB systems usually exhibit relatively low specific capacities limited by the cathode materials. In this study, we developed a one-step chemical vapor deposition method to prepare single-crystal orthogonal Nb2O5 nanotubes for serving as high-performance electrode materials for RAIBs, showing a high reversible capability of 556 mA h g-1 at 25 mA g-1 and good thermal endurability at elevated temperatures (50 °C).

Determination of complex optical constants and photovoltaic device design of all-inorganic CsPbBr perovskite thin films.

All-inorganic perovskites exhibit interesting properties and unprecedented stability compared to organic-inorganic hybrid lead halide perovskites. This work focuses on depositing and characterizing cesium lead bromide (CsPbBr) thin films and determining their complex optical constants, which is a key requirement for photovoltaic device design. CsPbBr thin films are synthesized via the solution method followed by a hot-embossing step to reduce surface roughness.

Nitrogen-Doped Carbon Nanotube Forests Planted on Cobalt Nanoflowers as Polysulfide Mediator for Ultralow Self-Discharge and High Areal-Capacity Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries with high theoretical energy density have caught enormous attention for electrochemical power source applications. However, the development of Li-S batteries is hindered by the electrochemical performance decay that resulted from low electrical conductivity of sulfur and serious shuttling effect of intermediate polysulfides. Moreover, the areal capacity is usually restricted by the low areal sulfur loadings (1.

Interface Engineering of Anchored Ultrathin TiO/MoS Heterolayers for Highly-Efficient Electrochemical Hydrogen Production.

An efficient self-standing hydrogen evolution electrode was prepared by in situ growth of stacked ultrathin TiO/MoS heterolayers on carbon paper (CP@TiO@MoS). Owing to the high overall conductivity, large electrochemical surface area and abundant active sites, this novel electrode exhibits an excellent performance for hydrogen evolution reaction (HER). Remarkably, the composite electrode shows a low Tafel slope of 41.

Porous-Shell Vanadium Nitride Nanobubbles with Ultrahigh Areal Sulfur Loading for High-Capacity and Long-Life Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries hold great promise for the applications of high energy density storage. However, the performances of Li-S batteries are restricted by the low electrical conductivity of sulfur and shuttle effect of intermediate polysulfides. Moreover, the areal loading weights of sulfur in previous studies are usually low (around 1-3 mg cm) and thus cannot fulfill the requirement for practical deployment.

CsPbSnIBr Based All-Inorganic Perovskite Solar Cells with Exceptional Efficiency and Stability.

The emergence of perovskite solar cells (PSCs) has generated enormous interest in the photovoltaic research community. Recently, cesium metal halides (CsMX, M = Pb or Sn; X = I, Br, Cl or mixed halides) as a class of inorganic perovskites showed great promise for PSCs and other optoelectronic devices. However, CsMX-based PSCs usually exhibit lower power conversion efficiencies (PCEs) than organic-inorganic hybrid PSCs, due to the unfavorable band gaps.

Solution synthesis and phase control of inorganic perovskites for high-performance optoelectronic devices.

An efficient method to synthesize well-crystallized inorganic cesium lead halide perovskites (CsPbX, X = I or Br) with high yield and high reproducibility was proposed. Notably, the as-prepared CsPbI in the yellow orthorhombic phase (y-CsPbI) can be easily converted to the black cubic perovskite phase CsPbI (b-CsPbI) after thermal annealing. Furthermore, two-terminal photodetectors and all-inorganic perovskite solar cells based on b-CsPbI were fabricated, exhibiting high performances.