Liangliang Wu

Electrochromic devices have emerged as promising candidates for non-emissive displays due to their particular photoelectric performance in complex lighting environments. They exhibit considerable potential in emerging fields such as Internet of Things terminals, flexible wearables and human–computer interaction interfaces. In this study, we developed a low-power electrochromic display based on a Pt/FTO (Fluorine doped tin oxide) electrocatalytic counter electrode and a Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) porous gel electrolyte. The Pt catalyst enhances Br⁻/Br³⁻ redox reactivity, which reduces the driving voltage from 2 V to 1 V, and accelerates the electrode reaction kinetics. It is systematically explained by the Density Functional Theory (DFT) calculations and electrochemical characterization. Furthermore, we demonstrate a proof-of-concept multicolor display incorporating the electrocatalytic counter electrode with various viologen derivatives. This approach provides a significant advancement toward next-generation high-performance displays and is supportive of the development of energy-efficient optoelectronic devices.

Airy beams exhibit enormous application potential in the field of optics and microwave owing to their unique self-bending, self-accelerating, and non-diffracting characteristics. In this paper, the Airy beams are dynamically generated and manipulated in both reflection and transmission spaces utilizing a full space programmable metasurface, which can achieve an approximately 360° phase coverage in the reflection space and a nearly 180° phase coverage in the transmission space in the operating frequency band from 6 GHz to 7 GHz. The direct current (DC) bias voltage is applied to the varactor diodes integrated on the metasurface by precise control of the external feeding system, allowing dynamic generation and regulation of Airy beams. Numerical simulations and experimental measurements are performed at 6.5 GHz. The Airy beams with parameters a = 56 and 61 are generated in the transmission space, while the Airy beams with parameters a = 71 and 81 are achieved in the reflection space. The parabolic propagation trajectory of the main beams and acceleration in the transverse planes can be observed. The good agreement between the simulated and measured results demonstrates that the metasurface can dynamically generate and manipulate the Airy beams in full space. The suggested Airy beam manipulation system has a wide range of applications, including optical particle manipulation, imaging, and difficult terrain exploration.

Viologen‐based electrochromic devices have attracted great attention because of their tremendous potential in building energy conservation and low power display. However, the unsatisfactory performance at lower voltage limits their application, while the high driving voltage increases the energy consumption as well as safety risk. Herein, an electrocatalytic strategy is proposed for high‐performance viologen‐based electrochromic devices. Copper oxide (CuO_x) nanoparticles are uniformly deposited on the F‐doped Tin Oxide (FTO) glass for enhancing the catalytic activity of Br⁻/Br₃⁻ redox couple, thereby promoting the interfacial charge transfer. The driving voltage can be reduced by ≈30% without sacrificing its high transparency (up to 80%) and the cycling stability can be significantly improved within 200 cycles. Large‐area smart windows and electrochromic displays are fabricated, which can be driven by the 1.5 V dry battery. This work opens up a new path to optimize the electrochromic performance of viologens and also lays the foundation for the application of catalysis in optoelectronic devices.

Transition metal carbides and nitrides (MXenes), as a large family of emerging two-dimensional materials, have demonstrated extraordinary performance in many fields such as electronics, optics and energy storage. However, their susceptibility to oxidation during preparation and storage in ambient air environment is undesirable for long-term and stable applications. Here, we have demonstrated that the spontaneous oxidation of Ti ₃ C ₂ T _x can be harnessed ingeniously to prepare Ti ₃ C ₂ T _x /TiO ₂ in situ formed heterojunctions. Furthermore, a self-powered ultraviolet photodetector was constructed based on the photoelectrochemical performance of Ti ₃ C ₂ T _x /TiO ₂ heterojunctions. Since the highly conductive Ti ₃ C ₂ T _x can promote the separation and transfer of photogenerated carriers in TiO ₂ , the prepared photodetector exhibits high responsivity (2.06 mA W ⁻¹ ), short rise and decay times (45 and 69 ms) and long-term stability. This work demonstrates the controllable synthesis of Ti ₃ C ₂ T _x /TiO ₂ heterojunctions and provides a new promising potential of MXenes for photodetection applications.

Electrochromic displays with bistable color states provide a promising means toward transparent human–machine interfaces. However, the need for external power and the weak optical modulation in the visible light region of most electrochromic devices hinder their practical applications in displays. Here we prepare the MoO_3–y/WO_3–x films based on MoO_3–y nanosheets, which show a dark blue color that matches the response of the eye and meets visual comfort standards compared to pure WO_3–x film. By introducing the highly transparent Al³⁺ ion hydrogel layer, a convenient electrochromic device driven by the internal chemical potential has been designed. The device based on the MoO_3–y /WO_3–x film exhibits a high optical modulation in the whole visible light range and can operate at self-powered mode with fast response speed and excellent cycle stability. Moreover, we develop an ionic writing board based on the MoO_3–y/WO_3–x film to surmount the fixed display information issue in conventional electrochromic displays. The ionic writing board exhibits excellent visual display quality and realizes arbitrary writing with a self-powered characteristic. This work provides a simple mechanochemical synthesis procedure of MoO_3–y nanosheets and an ingenious design of self-powered electrochromic devices, which will enable the development of next-generation high-performance electrochromic displays.

Electrochromic technology plays a significant role in energy conservation, while its performance is greatly limited by the transport behavior of ions and electrons. Hence, an electrochromic system with overall excellent performances still need to be explored. Initially motivated by the high ionic and electronic conductivity of transition metal carbide or nitride (MXene), we design a feasible procedure to synthesize the MXene/WO_3−x composite electrochromic film. The consequently boosted electrochromic performances prove that the addition of MXene is an effective strategy for simultaneously enhancing electrons and ions transport behavior in electrochromic layer. The MXene/WO_3−x electrochromic device exhibits enhanced transmittance modulation and coloration efficiency (60.4%, 69.1 cm² C⁻¹), higher diffusion coefficient of Li⁺ and excellent cycling stability (200 cycles) over the pure WO_3−x device. Meanwhile, numerical stimulation theoretically explores the mechanism and kinetics of the lithium ion diffusion, and proves the spatial and time distributions of higher Li⁺ concentration in MXene/WO_3−x composite electrochromic layer. Both experiments and theoretical data reveal that the addition of MXene is effective to promote the transport kinetics of ions and electrons simultaneously and thus realizing a high-performance electrochromic device. This work opens new avenues for electrochromic materials design and deepens the study of kinetics mechanism of ion diffusion in electrochromic devices.