W₁₈O₄₉ is a promising multifunctional material for electrochromic energy storage applications, owing to its abundant oxygen vacancies and distinctive crystalline structure. However, the contradiction between the high transmittance modulation for electrochromism and the high material loading for energy storage severely restricts the development of W₁₈O₄₉ in multifunctional smart windows. This work found that different metal doping (Mo, Ti, Fe) exhibited significant differences in regulating the electrochromic performance and energy storage of W₁₈O₄₉. And the oxygen vacancies of W₁₈O₄₉ can be further controlled by adjusting the metal doping concentration, simultaneously achieving excellent electrochromic properties and energy storage. 5% Ti-doped W₁₈O₄₉ not only exhibits a high transmittance modulation of 82.3% (633 nm) and 81.0% (1050 nm) with fast coloration/bleaching times of 9.8/5.8 and 3.8/5.8 s, but also shows a good energy storage of 32.5 mF·cm⁻² at 0.1 mA·cm⁻². Theoretical calculations indicate Ti doped W₁₈O₄₉ shows a more delocalized characteristic in band decomposition charge densities and a lower diffusion energy barrier, which is conducive to enhancing the electrochemical performance. This work demonstrates metal doping plays a significant role in simultaneously regulating electrochromism and energy storage, providing a new perspective for the development of multifunctional electrochromic materials.

Organic–inorganic hybrid perovskites are quite promising candidates in the field of electromagnetic wave (EMW) absorption due to their unique physicochemical properties. However, it is still a considerable challenge to satisfy the light weight, broad bandwidth, and strong absorption properties simultaneously. Herein, the solution of methylammonium lead iodide (MAPbI₃) perovskites was infiltrated into the pores of reduced graphene oxide (rGO) aerogels. After drying, a series of MAPbI₃/rGO composite aerogel (MGA) materials were synthesized by anchoring the MAPbI₃ perovskite nanoparticles to rGO sheets with the assistance of rGO templates. Through the adjustment of component ratios, excellent EMW absorption properties are obtained with the synergistic effects of polarization loss, conduction loss, and multiple reflection and scattering of MAPbI₃ and rGO. The porous structure of the aerogel and the suitable group distribution ratio allowed the MGA-4 samples to obtain excellent impedance matching and ultra-low density of ~ 7.69 mg·cm⁻³. At a low filling ratio of 15 wt.%, the MGA-4 sample simultaneously achieves highly efficient and broadband EMW absorption performance at a thin thickness. The MGA-4 sample obtained a minimum reflection loss value of −64.35 dB and the effective absorption bandwidth (EAB) value of 5.4 GHz at a thickness of 2.08 mm and a maximum EAB (EAB_max) value of 6.2 GHz under 2.22 mm. The MGA-5 sample obtained a maximum EAB value of 6.4 GHz with the thinckness of 2.16 mm. Furthermore, the simulation results of the radar cross-section (RCS) verified the component-optimized composites are capable of achieving excellent EMW attenuation. This paper provides a new approach and valuable reference for the development of hybrid perovskite-based microwave absorption materials with lightweight, ultra-broadband, and strong absorption properties.