Aqueous electrochromic battery (ECB) is a multifunctional technology that shows great potential in various applications including energy-saving buildings and wearable batteries with visible energy levels. However, owing to the mismatch between traditional electrochromic materials and the electrolyte, aqueous ECBs generally exhibit poor cycling stability which bottlenecks their practical commercialization. Herein, we present an ultrastable electrochromic system composed of lithium titanate (Li4Ti5O12, LTO) electrode and Al3+/Zn2+ hybrid electrolyte. The fully compatible system exhibits excellent redox reaction reversibility, thus leading to extremely high cycling stabilities in optical contrast (12 500 cycles with unnoticeable degradation) and energy storage (4000 cycles with 82.6% retention of capacity), superior electrochromic performances including high optical contrast (∼74.73%) and fast responses (4.35 s/7.65 s for bleaching/coloring), as well as excellent discharge areal capacity of 151.94 mAh m–2. The extraordinary cycling stability can be attributed to the robust [TiO6] octahedral frameworks which remain chemically active even upon the gradual substitution of Li+ with Al3+ in LTO over multiple operation cycles. The high-performance electrochromic system demonstrated here not only makes the commercialization of low-cost, high-safety aqueous-based electrochromic devices possible but also provides potential design guidance for LTO-related materials used in aqueous-based energy storage devices.
Ultra-thin-walled tubes of magnesium alloys have received more and more attention in producing precision components for medical devices. Therefore, thin-walled tubes with high quality are desperately needed. In this study, the process of multi-pass variable wall thickness extrusion was carried out on an AZ80 + 0.4%Ce Mg alloy with up to five passes—one-pass backward extrusion and four-pass extension—to fabricate the seamless thin-walled tube with an inside diameter of 6.0 mm and a wall thickness of 0.6 mm. The average grain size decreased from 46.3 μm to 8.9 μm at the appropriate deformation temperature of 350 °C with the punch speed of 0.1 mm/s. X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM), and the Vickers hardness (HV) tester were utilized to study the phases, microstructure, and hardness evolution. It can be observed that low deformation temperatures (240 °C and 270 °C) and low strain (1 pass extrusion and 1 pass extension) lead to twins that occupy the grains to coordinate deformation, and a slip system was activated with the accumulation of strain. The results of the Vickers hardness test showed that twinning, precipitation of second phases, twinning dynamic recrystallization (TDRX), and work hardening were combined to change the hardness of tubes at 240 °C and 270 °C. The hardness reached 93 HV after the third pass extension without annealing at 350 °C.
Stacked 2D perovskites provide more possibilities for next generation photodetector with more new features. Compared with its excellent optoelectronic properties, the good dielectric performance of metal halide perovskite rarely comes into notice. Here, a bifunctional perovskite based photovoltaic detector capable of two wavelength demultiplexing is demonstrated. In the Black Phosphorus/Perovskite/MoS2 structured photodetector, the comprehensive utilization of the photosensitive and dielectric properties of 2D perovskite allows the device to work in different modes. The device shows normal continuous photoresponse under 405 nm, while it shows a transient spike response to visible light with longer wavelengths. The linear dynamic range, rise/decay time, and self‐powered responsivity under 405 nm can reach 100, 38 µs/50 µs, and 17.7 mA W‐1, respectively. It is demonstrated that the transient spike photocurrent with long wavelength exposure is related to the illumination intensity and can coexist with normal photoresponse. Two waveband‐dependent signals can be identified and used to reflect more information simultaneously. This work provides a new strategy for multispectral detection and demultiplexing, which can be used to improve data transfer rates and encrypted communications. This work mode can inspire more multispectral photodetectors with different stacked 2D materials, especially to the optoelectronic application of the wide bandgap, high dielectric photosensitive materials.
Lead-free perovskite has attracted great attention in realizing high-performance optoelectronic devices due to their excellent atmospheric stability and nontoxic characteristics. Although a pronounced ion migration effect has been observed in this new class of materials, its potential in enhancing the overall device performance is yet to be fully explored. In this work, we studied the effect of ion migrations on the carrier transport behavior and found that the recoverable migration process can contribute to enhancing the on/off ratio in a lead-free CsCu 2 I 3 single-crystal microrod-based photodetector. In detail, we synthesized CsCu 2 I 3 single-crystal microrods via an in-plane self-assembly supersaturated crystallization approach. These microrods with well-defined morphologies were then used to construct ultraviolet (UV)-band photodetectors, which outperform most reported lead-free perovskite photodetectors based on individual single crystals. Simultaneously, ion migration can result in asymmetric band bending in the two-terminal device, as confirmed by surface potential profiling with Kelvin probe force microscopy (KPFM). Such an effect can be harnessed to increase the on/off ratio by almost an order of magnitude. Furthermore, the lead-free CsCu 2 I 3 single crystal exhibits excellent thermal and air stabilities. These findings demonstrate that the CsCu 2 I 3 single-crystal microrods can be used in stable and efficient photodetection, and the ion migration effect can potentially be utilized for improving the optoelectronic performance of lead-free devices.
Recently, halide perovskite materials have shown great potential in photodetection for their large light absorption coefficient and long carrier diffusion length. In contrast to the reported sandwich-structured devices and single-junction...
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