Flexible, transparent heaters have rapid response
Flexible, transparent heaters have rapid response lead image
A transparent heater, made from growing thin layers of doped zinc oxide (ZnO) on mica with van der Waals epitaxy, exhibits rapid thermal response and better bending properties than previously realized. These flexible, transparent heaters described in Applied Physics Letters have a number of applications, including window defogging and deicing for liquid crystal displays, and in electronic devices designed for use in extreme environments.
The authors used pulsed laser deposition to grow a film of aluminum-doped ZnO (AZO) on a sheet of muscovite mica. Mica has a layered structure similar to graphene in which adjacent layers are attracted to one another via van der Waals forces, rather than covalent bonds. The rapid thermal response of the resulting samples depends on a number of properties, but one of the most important is the thickness of the mica substrate, which can be quite thin due to the mechanical exfoliation process used to produce the substrate layer.
The resulting AZO-mica devices reach their target temperature in under two seconds when applying 6 volts. This is one to two orders of magnitude faster than for carbon-based and AZO-glass heaters. The ratio of average transmittance of visible light through the transparent electrode to its electrical resistance can be used to quantify device performance.
This work reports a ratio of 17.6 for AZO-mica, over an order of magnitude larger than for similar devices made from AZO layered over a polyethylene terephthalate (PET) substrate. PET is one of the most widely used materials for existing flexible, transparent heaters, so this work represents a considerable technological advance.
Source: “van der Waals epitaxy of Al-doped ZnO film on mica as a flexible transparent heater with ultrafast thermal response,” by Shanming Ke, Jing Xie, Chang Chen, Peng Lin, Xierong Zeng, Longlong Shu, Linfeng Fei, Yu Wang, Mao Ye, and Danyang Wang, Applied Physics Letters (2018). The article can be accessed at https://doi.org/10.1063/1.5010358 .
