Title : Tungsten trioxide cathode films for electrochromic devices
Abstract:
Template-assisted sol gel chemistry provides a versatile approach to introduce order and porosity into nanostructured materials. However conventional evaporation induced self-assembly techniques are not easily scaled to produce films with sufficient thickness over large areas at the throughput required by electrochromic windows. The principles of sol gel chemistry may be deployed using ultrasonic spray deposition (USD) for scalable synthesis of nanocrystalline WO3 films with unrivalled electrochromic performance are demonstrated. Systematic manipulation of sol chemistry enabled the production of mesoporous films with high specific surface area (>100 m2/g), mean pore sizes of ~5 nm, and narrow pore size distributions. Film thickness is found to be proportional to the sol concentration and number of spray passes, and various combinations are shown to produce films capable of modulating >98% of incident solar radiation in the visible spectrum (450–900 nm). Elimination of haze enables full transmission in the bleached state, while the broadband coloration is attributed to the exceptionally high charge density (>120 mC/cm2). The materials have good switching speeds which improve with specific surface area, and the long term durability is promising.
Audience Takeaway:
- The audience will be able to use what they learn to improve the performance of the materials.
- This research will help the audience to design a material that exhibits higher charge density of optoelectrochemical device.
- This research can provide a practical solution to enhance the specific surface area of a material.
