Transparent Conducting Electrodes from Conducting Polymer Nanofibers and Their Application as Thin-Film Heaters

Transparent conducting electrodes attract attention in relation to solar cells, touch panels, displays, e-readers, and transparent heaters. In many cases, rarefied metal nets with optical transmittance of ≈90% and with minimal sheet resistance are sought after. Here, a mesh of conducting polymer nanofibers is developed as a transparent conducting electrode. A sheet resistance of 8.4 kΩ sq^-1 with 84% optical transmittance is achieved with polyethylene oxide/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEO/PEDOT:PSS) blended polymer nanofibers. This study also demonstrates that such nanofiber being deposited on a glass substrate can be used as a transparent film heater in relevant applications such as window heating or displays at harsh environments. Such a transparent heater is rated at 0.41 W in.^-2 for 120 V. It is also capable of heating a substrate up to ≈70 °C in 4 min at 60 V from room temperature without any degeneration of nanofiber network, rendering itself as a practically useful transparent heater. The performance of the PEO/PEDOT:PSS nanofiber-coated transparent glass heater is comparable to that of the relatively expensive indium tin oxide thin-film heaters.