Interlayer UV-Photo-Cross-Linking Endowed PEDOT:PSS-Based Electrochromic Smart Windows with Highly Conductive and Physically/Chemically Multicross-Linked Mechanical Architectures

While electrochromic smart windows (ESWs) significantly enhance living comfort in energy-efficient buildings, their structural interfaces remain highly vulnerable to environmental factors and subsequent delamination. This study developed a UV-curing interfacial engineering strategy by synchronously incorporating photosensitive poly(ethylene glycol) dimethacrylate (PEGDMA) into both the electrolyte layer and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) active layer to construct a multicross-linked network. The PEDOT:PSS/PEGDMA film under optimal component ratios showed highly conductive feature (89.99 S cm⁻¹) with excellent water/solvent resistance. Spectroelectrochemical characterization revealed that the bleached-state PEDOT:PSS/PEGDMA film delivered outstanding optical properties at 642 nm, including a 95.87% high transmittance, 82.2% optical contrast (ΔT), and a remarkable coloration efficiency (CE) of 1201.62 cm² C⁻¹, though its ΔT declined from 82.2 to 62.63% after 20,000 s. UV-cured ESWs achieved a maximum transmittance of 92.53%, a ΔT of 77.42%, and a CE of 731.71 cm² C⁻¹. Following 500 cycles (20,000 s) of testing, the ΔT of the UV-cured ESWs dropped from 77.42 to 70.89%, while maintaining an optical memory effect for as long as 2 h post power-off. The photothermal barrier performance of such ESWs based on PEDOT:PSS/PEGDMA in the colored state was also demonstrated. This research provides a crucial material and technical foundation for advanced ESWs, paving the way for their broader application as switchable glass not only in smart architecture but also in vehicles, such as for intelligent sunroofs and autodimming rearview mirrors.