Materials research is an important area for the field of flexible and printed electronics, and much of that work is centered on finding replacements for indium tin oxide, or ITO.

ITO is transparent and offers excellent electrical conductivity. It is primarily deposited on thin films through the use of vapor deposition, and is frequently found in OLEDs, solar cells and touch displays.

However, ITO also has numerous drawbacks. Due to the limited supply of indium, the cost of ITO is high, although ITO manufacturers have been reducing their prices. There is a limited supply of indium. Vapor deposition is also an expensive process relative to other printing and coating processes. ITO’s brittleness is also of concern to flexible display manufacturers.

With this in mind, Flexibilis was formed to research alternatives to ITO. Flexibilis is a pan-European collaborative R&D project which began in March 2013 and finishes in February 2016. The project is already addressing a number of problems that inhibit the uptake of flexible OLED and PV technologies.

Flexibilis has two primary goals: finding an ITO replacement and discovering flexible barrier materials.

“In simple terms, the project seeks to be in a position to define if there is a replacement material for ITO and whether it still yields the cost, flexibility and lifetime efficiency requirements at pilot production scale, and to identify whether replacement materials for ITO exist that are suitable for OLED and PV applications.” said Phil Hollis of the Centre for Process Innovation (CPI), who is the program manager for Flexibilis “In 16 month’s time, the consortium will be well placed to answer the million-dollar question, having analyzed and evaluated a number of potential materials both in the lab and in a manufacturing environment.

“The second goal of the project is to evaluate the performance and price points of novel flexible barrier materials for OLED and PV applications,” Hollis added. “The consortium is utilizing a range of technologies, including sputtering and chemical vapor deposition techniques, to achieve this. The alternative materials under evaluation are benchmarked against more established barrier products that are in the market today.”

Hollis noted that the commercialization of OLED- and PV-based applications such as flexible displays, lighting and energy harvesting devices is heavily dependent on the use of ITO for transparent conducting films, and encapsulation films with high performance barrier properties. He added that alternative technologies are needed to advance the field of flexible and printed electronics.

“There is an industry need for the creation of alternative technologies and materials that have equal performance but deliver low cost, sustainable, transparent and flexible products for these applications,” Hollis said.

The problem is that while the ITO alternatives work well in the lab, manufacturing is another story.

“Throughout Europe, it is proving extremely difficult to develop the manufacturability of these alternative materials beyond laboratory scale to the position where they are available in large area quantities to enable a price compatible with supporting market growth,” Hollis reported.

Barrier technology also needs to be developed for flexible applications.

“The project also seeks to produce a high performance flexible barrier that is compatible with OLED and PV devices,” Hollis said. “These types of devices require a water barrier showing a water transmission rate between 10-4 and 10-6 g/m2 per day. This is extremely challenging and the race is on within Europe to achieve these results.”

To solve these challenges, the Flexibilis project brings together some leading European researchers to develop the technologies needed for the replacement of ITO in flexible electronic applications. The project includes CPI; Teer Coatings Limited (part of Miba); the University of Bolton; and NanoTecCenter Weiz Forschungsgesellschaft mbH; and High Tech Coatings GmbH (also part of Miba).

Hollis said that CPI’s role in the project as a technology innovation center is to manage the project and provide the infrastructure and skill set needed to take the identified replacement materials from lab scale to a pilot production environment.

“CPI is also providing OLED and PV demonstrator samples with NanoTecCenter Weiz,” Hollis added. “The project draws upon Miba’s extensive coatings capability and utilizes Bolton University’s knowledge of multi-scale materials modeling and nanomaterials. In addition to the samples, NanoTecCenter Weiz is bringing vital experience in the research and development of nanoscale materials and nanotechnology for OLED and PV applications.”

While confidentiality agreements preclude releasing any details of the testing until early 2016, Hollis said that some of the replacement materials look promising.

“Over the first 18 months, we have evaluated a series of materials in the replacement of ITO,” Hollis said. “We can say that a number of materials have shown enough promise that they are in the process of being tested beyond lab scale development and are moving towards market scale devices.”

“Future development work beyond the lifetime of the project will be focused on upscaling candidate materials in devices beyond demonstration scale to a price point that enables volume production so that we can start to see the emergence of novel OLED and OPV applications in the mass market,” Hollis concluded.