The ITO replacement for flexible panels

Indium-Tin Oxide (ITO) has been widely used as transparent conducting material for various display devices. Whereas this material has some problems, such as the conductivity and the flexibility. High conductivity is required for responsivity when the panel size becomes larger. Flexibility is required at bending or folding. For those reasons, many effort has been made to develop alternatives to ITO.

ITO/Ag/ITO multilayer structure is one of the alternatives to ITO, which has a high transmittance and low resistance. Moreover, it is expected that it can improve the flexibility due to the ductility of Ag. One of the biggest challenge for ITO/Ag/ITO structure is the instability of ultra-thin Ag film, in other words, the degradation by the Ag agglomeration. Theoretically, when Ag film becomes thinner, the film transmittance becomes higher due to the decrease of the film absorption. Actually, Ag film becomes discontinuous (‘the aggregated Ag islands’) when the film is thinner than a certain thickness. As the result, the optics and electric characteristics degrades considerably. Furthermore, a thermal factor promotes the film agglomeration. Therefore, thermal resistance is also a big challenge. 

Some Ag alloys with added elements can overcome the above challenges.It is expected that this Ag alloy can make the practical ITO/Ag/ITO structure a substitute for ITO.