Ultrasonic spray deposition of high performance WO3 films using template-assisted sol–gel chemistry

Tungsten oxide (WO3) thin films with nanoscale porosity were prepared by adopting templating sol–gel chemistry to ultrasonic spray deposition (USD). It was found that the electrochromic performance was strongly correlated to the annealing conditions used to remove the triblock copolymer template. Optimized films display state-of-the-art performance with respect to coloration efficiency (> 50 cm2/C), optical modulation (> 75%), and switching times (< 10 s). The films exhibit good durability, displaying disordered, nanocrystalline morphology. USD is compatible with in line manufacturing, and the performance was notably improved over films deposited by spin coating using the same chemistry.

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► Mesoporous WO3 thin films were prepared using scalable ultrasonic spray deposition.
► This method employs sol–gel chemistry with a triblock copolymer templating agent.
► State-of-the-art coloration efficiency (> 50 cm2/C), modulation (> 75%), switching times (~ 6 s)
► Performance is correlated to the nanoscale morphology produced during annealing.
► The disordered, nanocrystalline films exhibit good stability.