Multiscale Synergistic Engineering of Constructed Devices Enables Ultrafast Real-Time Dynamic Photochromic-Electrochromic Optical Modulation

Photochromic–electrochromic dual-responsive devices hold great promise for dynamic optical modulation and energy-efficient smart systems. However, achieving rapid, reversible, and bidirectional color switching remains a significant challenge, limited by unbalanced charge transport and poor interfacial stability. Here, a multiscale synergistic design strategy is presented that integrates nanostructure engineering, charge transport regulation, and interface optimization. Molybdenum-doped tungsten oxide quantum dots are composited with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate to construct a dual-responsive functional layer. Mo doping introduces additional oxygen vacancies in tungsten oxide lattice, enhancing electrochemical activity and facilitating coupled ion/electron transport within the composite. The engineered interfacial architecture suppresses charge accumulation, accelerating the photo response and enhancing the synergistic photoelectric performance. The device fabricated by integrating a functional layer and a hydrogel electrolyte between two indium tin oxide electrodes exhibit bidirectional optical control: under a −3 V bias, visible light-induced coloration is enhanced, reducing transmittance from 19.6% to 10.5%; applying a +1.5 V bias enables ultrafast bleaching within 3 s—6 600 times faster than passive fading. Additionally, the device achieves a temperature drop of 10.25 °C, demonstrating its excellent passive insulation performance. This work offers a pathway toward next-generation chromic devices with fast, reversible, and energy-efficient performance for adaptive optoelectronics and sustainable building technologies.