Porous Electrochromic Structures: A Review

Electrochromic technology has gained significant attention due to its wide applications in smart windows, adjustable optoelectronic devices, and energy storage systems. The strategic incorporation of porous architectures has emerged as a pivotal approach for enhancing electrochromic material performance. This approach effectively addresses critical challenges, including volume expansion mitigation, stability enhancement, and ion transport efficiency optimization, thereby improving both electrical conductivity and response kinetics. This review systematically examines principal strategies and synthesis methodologies for developing porous electrochromic materials. First, nanoparticle-stacked particulate films demonstrate enhanced electrolyte permeability through their inherent porous configurations, significantly increasing accessible reactive sites. Second, template-assisted approaches utilizing hard templates (e.g., polystyrene [PS] nanospheres, silica nanospheres) and soft templates (e.g., cetyltrimethylammonium bromide [CTAB], polyethylene glycol [PEG]) enable precise pore size regulation while effectively mitigating structural deformation. Third, coordination modulation strategies involving the length adjustment of organic ligands and the functionalization of metal/organic centers facilitate the fabrication of nanocrystalline mesoporous materials with uniform pore distribution, offering tailored electrochromic optimization pathways. Through in-depth analysis of these porous design strategies, this review elucidates the critical structure-performance relationships between porous architectures and electrochromic behaviors. The findings provide valuable guidance for the rational synthesis of high-performance electrochromic materials, thereby advancing the development of next-generation electrochromic technologies. © 2025 The Author(s). SmartMat published by Tianjin University and John Wiley & Sons Australia, Ltd.