Xiudi Xiao

At present, the realization of multi-band regulation has gradually become the main research trend of electrochromism. It aims to achieve artificial control of the visible band for the change of the external color of the object, and the electronically controllable infrared emissivity makes it further enhance the camouflage ability. Regrettably, the function of achieving multi-band regulation is accomplished by two independent parts in most studies, which implies the non-intelligence of the design. Here, a novel electrochromic electrode-based WO _x photonic crystal (PC) was proposed, which was constructed by an alternate depositing WO _x layer with different substrate angles on indium-tin-oxide (ITO) coated glass by the glancing-angle magnetron sputtering at room temperature. Different initial colors were obtained for WO _x PC films through the regulation of refractive index and thickness. Combined with the electrochromic property, the color gamut of WO _x PC films has been further expanded, achieving multi-color tunability. Importantly, the average modulation of maximum infrared emission can be achieved at 0.29 (3–5 μm) and 0.18 (8–14 μm), indicating that the simultaneous realization of visible-infrared dual bands regulation based on a single WO _x functional layer is expected to provide a new solution for multi-band regulation.

A frost-resistant hydrogel electrolyte with high ionic conductivity at −40 °C has been developed for wearable Zn//WO _{3− x} electrochromic devices.

V₂O₅, an inorganic electrochromic (EC) material with rich color variation and natural abundance, has received extensive attention due to its polychromatic properties during the EC process. However, research on achieving multicolor tuning by combining the structural color generated from the light-matter interactions with the EC properties of V₂O₅ is rare. Here, based on the detailed investigation of the process parameters of V₂O₅, we propose a new optical design of the colorful EC electrode with the V₂O₅/W Fabry–Pérot cavity constructed by magnetron sputtering on the glass substrate. By varying the thickness of the top layer of V₂O₅, the reflective electrodes exhibit seven different initial colors. Importantly, the designed EC electrode exhibits a vivid and rich wide color gamut when applying a voltage of −0.6–1.6 V. After 200 cycles, the color of the EC electrode and device can still change, demonstrating the potential of the glass/W/V₂O₅ EC electrodes in the fields such as camouflage and anti-counterfeiting.

Three strategies for achieving multicolor based on inorganic electrochromic materials: intrinsic color, structural color, and stacked color.

The pursuit of high‐resolution and advanced anti‐forgery technology has stimulated a growing demand for anti‐counterfeiting and encryption strategies with real‐time response and high security. Polarized patterns taking the advantage of high security, rapid response, simple operation, and great selectivity enable real‐time and non‐invasive detection by monitoring in different polarization directions. Here, a new strategy to design and fabricate the polarized CsPbBr₃ quantum dot (QD) line arrays by femtosecond (fs) laser writing in a transparent glass matrix is proposed. The obtained line array structures endow isotropic CsPbBr₃ QDs with macroscopic polarized emission with a polarization degree up to 0.189. Through programable design, the authors have created 2D and 3D polarized luminescent patterns made up of vertical and horizontal lines inside the glass for polarization‐sensitive optical anti‐counterfeiting patterns. The CsPbBr₃ QD line arrays used in anti‐counterfeiting can be well maintained in the water environment. The successful demonstration of the laser writing CsPbBr₃ QD polarization structures in glass highlights the versatility of anti‐counterfeiting and encryption.

CsPbIBr₂ has shown great potential in the optoelectronics field due to its well‐balanced relationship between bandgap and durability among all‐inorganic perovskites materials. However, the CsPbIBr₂ thin films prepared by the traditional one‐step spin coating method suffer from unsatisfactory morphology, poor crystallinity, and high defect density, which lead to the degradation of device performance. Herein, a simple preannealing method is used to form unstable transition films which are then annealed at high temperature to obtain CsPbIBr₂ perovskite films with uniform morphology, free pinholes, and strong crystallinity. The performance of the device can be effectively improved due to the reduction of defects and the optimization of the contact between functional layers. Therefore, the power conversion efficiency of 9.6% is obtained, which is nearly 100% improvement compared with that of the control device.

All‐inorganic perovskite solar cells (PSCs) have been demonstrated to solve the thermal instability problem of organic–inorganic hybrid PSCs. Therefore, NiO _x film is prepared by electron beam evaporation as a hole transport layer of all inorganic CsPbIBr₂ PSCs. Then, the postannealing is used to promote the diffusion of NiO _x into the gold electrode, and enhance interface contact and reducing the electrical resistance of NiO _x /Au. After optimizing NiO _x /Au interface, the devices based on NiO _x achieved a power conversion efficiency (PCE) of 6.7%. Furthermore, the best all‐inorganic CsPbIBr₂ PSC free of encapsulation retains 95% of initial efficiency over 100 h at 85 °C. Herein, an effective postannealing strategy is provided for optimized NiO _x /Au interface to make stable and efficient all‐inorganic CsPbIBr₂ PSCs.