High performance transparent conductive oxides (TCOs) can provide a continuous electrically conductive surface when deposited onto a substrate, but over large areas (over a couple centimeters in dimensions), there can be significant voltage drops. This can be overcome by adding conductive busbars (metal lines) to create long-range high conductivity pathways. 

Typical devices using high-performance TCOs require busbars to achieve desirable performance. With higher electronic conductivity, there is significant reflection of radio frequency (RF) radiation.  The combination of TCO with busbars results in low sheet resistance and is unsuitable for large electrochemical devices, such as in smart windows. 

The alternative for TCOs with busbars is metal meshes since they have high conductivity, but the meshes also have drawbacks.  They provide a limited electrochemically active surface. They also lose RF transparency as their spacing separation distance approaches the wavelength of incoming electromagnetic radiation. Common metal meshes are square or hexagonal arrays of wires and effectively block all EM radiation above a certain wavelength. 

The ability to maintain sufficient conductivity of electrochemical device substrates while maintaining adequate RF transparency would allow for creation of new, useful electrochemical and electrochromic devices.