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INdustrial Scale Production of Innovative nanomateRials for printEd Devices

Periodic Reporting for period 3 - INSPIRED (INdustrial Scale Production of Innovative nanomateRials for printEd Devices)

Reporting period: 2018-01-01 to 2018-12-31

Traditional electronic manufacturing technologies are based on subtractive processing which often involves numerous expensive processing steps and can produce unwanted waste/pollution. Electronics manufacture in Europe using these traditional processes has become challenging due to high labour costs and stringent environmental legislation. As a result, global electronics manufacture is dominated by producers in the Far-East, with Europe losing market share.
Printed electronics is set to revolutionise the electronics industry over the next decade. It allows for the direct printing of a range of functional (conductive, resistive and semi-conducting) nano-scale materials (“nanomaterials”) formulations to enable a simpler, more cost-effective, high performance and high-volume processing. However, the migration towards low-cost, liquid-based, high resolution deposition and patterning using high throughput techniques, such as inkjet printing, requires that suitable functional nanomaterials and formulations (e.g. inks) are available for end users in industrially relevant quantities. Presently, there are issues with industrial supply of nanomaterials which are low cost, high performance, environmentally friendly and tailored for high throughput systems. Therefore, better collaboration is required between supply chain partners to ensure nanomaterial production and nanomaterial formulations are tailored for end use applications to meet this need. Also, suitable equipment/processes must be available to use these materials. The INSPIRED project was set up to address these fundamental issues, by linking partners from the full value chain for electronics manufacture.
With the end of the project approaching, we can summarize the work performed in the following areas.

Producing new materials

In the area of new materials synthesis, the work performed concentrated on up-scaling the production of three new nanomaterials formulations. These were copper nanoparticles for inks and pastes, silver nanowires and graphene nanoplatelets. During the project both the silver nanowires and graphene production was scaled up from lab-scale quantities to commercially available products manufactured at industrial scale. New formulations of the copper nanomaterials were produced to address the demonstrator devices successfully but were not fully scaled.
New manufacturing processes
Along with the new materials, came the requirement to handle them in new ways. In the project a range of new processing techniques were developed. These included laser processing to produce fine scale circuit patterns in all the materials; inkjet printing of the inks and spray coating of the nanowires and graphene. For the copper nanoparticle inks a novel laser sintering process was developed to produce conductive tracks with similar electrical properties of the conventional silver materials.

New demonstrator electronic devices

Using the new processes and materials developed during the project, a range of demonstrator electronic devices were produced to meet the requirements of the end-users of the project and to showcase the technologies. These demonstrators included capacitive touch screens using printed copper electrical connections or silver nanowire conductive coatings, LCD signage devices with silver nanowire transparent screens, and solar cells with low-cost printed copper electrodes.

Pilot production equipment

In order to produce real working devices, using the new materials and processes, there is also a requirement to demonstrate industrial scale equipment on which to use them. The key part of the machine concept was to facilitate manufacturing printed electronics devices on arbitrarily-sized substrates up to “Gen 5” (1.3 m x 1.1 m) to address the requirements of all the project partners and for tackling real-world scale samples e.g. full-scale solar cell panels. This pilot system, with inkjet printing laser pattering and sintering capabilities was built successfully and is in full operation at M-Solv. In addition to this large system, the project also produced two other pilot production machines for the end users: A silver nanowire and graphene spray coating system was produced and tested and a novel laser system to sinter the copper electrodes on solar cells, which was installed at one of the end-user’s sites.

Nanosafety

There are many known hazards of nanomaterials, and these may increase as the production volume is scaled-up, and these should be considered if there are plans to use a nanomaterial in a commercial capacity. INSPIRED brought together various partners in different sectors of the nanotechnology industry to help with studying the safety of nanomaterials throughout different scale-up processes. In this context, the INSPIRED project developed a wide range of guidelines and a Best Practice Guide to support the safe handling and use of conductive nanomaterials for printed electronics applications, considering integrated strategies to control the exposure to nanoparticles in industrial settings, and provide the end-users with appropriate knowledge to minimise and control the nanoparticles released.
Since the beginning of the project there have been a significant number of important advancements beyond the state-of-the-art. These are summarised here:

• A new exfoliation method for producing graphene was scaled up to pilot production.
• An advanced model has been developed for the plasma synthesis of copper nanoparticles.
• New copper nanoparticle-based inkjet inks have been developed with improved performance on transparent conductive substrates.
• New formulations of copper pastes were demonstrated with greater conductivity and adhesion than have been achieved previously.
• New improved optical designs for laser sintering have been developed.
• The pilot-scale inkjet and sintering system was the first of its kind and is a unique facility for the printed electronics industry.
• The first demonstration of working copper interconnects for CIGS solar cells was made.
• Highly transparent and conductive Ag nanowires have been developed and scaled up to production volumes.
• The first demonstration of working silver nanowire touch sensor has been formed by spray coating and laser pattering.
• Silver nanowire top contacts for CIGS cells have also been demonstrated for the first time.

The above developments beyond the state of the art have led to ten patent applications and 8 scientific publications so far. 118 dissemination & communication activities have taken place to date. The immediate impact will be on the advancement of the production of the nanomaterials, manufacture and performance of inks for printed electronics as well as the equipment for printing and processing these materials, and the advancement of their potential uses in touchscreens, displays and CIGS solar cells. In the longer term the project will have a direct positive impact across the entire printed electronics sector value chain, benefiting the nanomaterial suppliers, ink manufacturers, printing companies and equipment suppliers and the high value manufacturing sectors. The printed electronics developed from these nanoparticles will reduce the impact to the environment of hazardous chemicals used in current electronics processing. The health and safety assessments in INSPIRED will lead to guidelines for the safe use and production of the nanomaterials.
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