The table below provides a comparison of the two approaches. Film-type is the simplest to implement. Crucially, it decouples the production yield of the touch layer from that of the display layer. Furthermore, the films could be manufactured using lower cost assets. The scalability to larger areas will also be simpler and production speeds likely higher as R2R film production techniques can be deployed. Therefore, the film-based approach is a more accessible technology that offers an easier and lower cost roadmap towards larger-area flexible displays.
However, this approach falls short on performance. Material choices are now available which offer high flexibility and foldability. Metal mesh films are likely to be good enough for medium levels of folding. The picture for higher bending degrees becomes hazier, however technology options such as silver nanowires have already demonstrated that they can sustain the technology roadmap towards high bending levels. Clearly, all technology choices require further improvement however current issues are unlikely to be a fundamental showstopper. As such, transparent conductive layer technology choice itself is not a performance bottleneck.
The key advantage of this approach is that it eliminates the additional substrate, thus resulting in a thin and flexible solution. The challenge, however, is that it dramatically increases the cost of production defects in the touch layer as the entire stack- including the OLED and the TFT- will be thrown away. Success here, therefore, requires outstanding production know-how and optimization. Furthermore, this process ties up more expensive production assets on a usually low-cost item which is the touch layer. It is also likely to require slow and controlled deposition within the narrow parameter space limited by the already-deposited materials and layers. Importantly, it is not clear whether this approach can be readily scaled to larger areas or not. This is because one would require the inline TFE as well as the patterned touch electrode deposition processes to be scaled up without compromising quality or cost.
Top image: Royale Corporation