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  • Periodic Reporting for period 1 - CLEARSILVER (Industrial manufacturing of conductive, transparent and flexible electrodes with nanoinks fororganic electronic devices such as OPV and OLED lighting)

CLEARSILVER Report Summary

Project ID: 733723

Periodic Reporting for period 1 - CLEARSILVER (Industrial manufacturing of conductive, transparent and flexible electrodes with nanoinks fororganic electronic devices such as OPV and OLED lighting)

Reporting period: 2016-09-01 to 2017-02-28

Summary of the context and overall objectives of the project

Nowadays, Indium Tin Oxide (ITO) is the main material used for transparent conductive films (TCF). These films have significant drawbacks such as fragility, indium depletion and high manufacturing cost. A promising alternative is a conductive patterned grid based on silver nanoparticles covered with a protective and conductivity enhancing zinc oxide nano-layer.

To accelerate the uptake of this processing technology, the printed electronics market needs a complete solution of industrial inks and inkjet printing at large scale and high speed. This is the objective of the CLEARSILVER solution proposed by KELENN Technology (KT) - manufacturer of industrial solutions for inkjet printing - and Genes’Ink (GNK) - leader on the conductive and semi-conductive nanoinks market.

The CLEARSILVER project is coordinated by GNK in collaboration with KT. This partnership benefits from their core technical and business expertise. Since beginning 2014, GNK and KT have successfuly developed a complete pilot solution including nanomaterials kilo-scale manufacturing and an online demonstrator printer, KSCAN-PE400 presented at LOPEC 2016. The SME Instrument funding will support our objective to bring to the market a sustainable industrial solution for TCF manufacturing.

CLEARSILVER’s main objectives concerns business, technological, environmental and social aspects:

• Provide a higly conductive TCF manufacturing solution to customers to penetrate the new emerging markets of OPV and OLED.
• Take the leadership in the field of TCF first in OPV and OLED and at a later stage in flexible display.
• Offer a cost-effective process by direct patterning with inkjet printers for conductive designs.
• Decrease the consumption of raw material by 50 times (customers feedback).
• Increase the throughput by a factor of 100: process time reduced from 40 min to 20 s (customers feedback).

• Develop a solid alternative to ITO based TCF: Printed conductive nano-Ag grid onto PET substrates covered with a ZnO nanoink layer allowing surface homogenization and TCF properties enhancement.
• Transpose printed TCF technology from pilot scale to industrial scale (TRL 6 → TRL 8).
• Enable the use of nanoinks at industrial scale.
• Develop an industrial inkjet printing solution with a high printing speed of 40 m/min.
• Integrate online substrate pre-treatment and TCF post-treatment allowing high speed production.

• Promote safe-by-design approaches to comply with the EU regulatory strategies .
• Propose environmentally friendly and sustainable solutions allowing greener and cleaner world for present and future generations.

All these objectives are in direct line with long-terms investments and funding done by the EU to push from “lab to market” cutting edge technologies.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Over the first 6 months of the project, the work and the results obtained are:

• First printing tests of Ag nanoparticles based inks manufactured by GNK were performed
The CLEARSILVER TCF was first tested as flexible transparent electrodes by our Partner CSEM, which will be involved as sub-contractor for the project. Ag ink was deposited onto a PET substrate using a non-optimised grid design and electrical characterization were made. First results are very promising: the overall electrical performance the CLEARSILVER TCF is equal and even better than the flexible ITO:
o Sheet resistance down to 10 ohm/sq along with > 84% of relative transmittance.
o No loss of conductivity is observed under bending, which is a key requirement for flexible devices.
Simulations were performed by the CSEM (sub-contractor) in order to define the best grid design for optimum properties (Transparency > 91%; Sheet resistance (Rsq) < 15 Ohm/sq for 300 nm layer thickness).

• Industrialisation of the nanomaterials production with optimisation studies and scale-up on both silver and zinc oxide. This task aims at up-scaling existing GNK production processes. Study of the following parameters is ongoing:
o Effect of stirring and heating
o Purification steps optimisation
o Batch to batch reproducibility.
A pilot line was dedicated to the production of ZnO and AZO nanoparticles. After optimization, synthesis yield was enhanced from 25 to 75% and 40 nm particle size ZnO and AZO nanoparticles were produced. This synthesis allows the production of 5 L ZnO ink/batch.
Concerning Ag NPs upscaling process, for the moment we are able to produced 2.5 L ink/week. Synthesis up-scaling optimization is ongoing in order to adjust all parameters and enhance production capacity.

• Industrial scale Printer manufacturing
Work made by KT has focused on the S2S inkjet printer manufacturing and the testing of the inks solution from Genes'Ink. Printing has been carried out in order to reach line width closed to 20 µm along with printing speed equal to 30 m/min. Software interface and tuning of each function and parameter of the machine have also been conducted. First S2S industrial printer was manufactured. To industrialize and attain a high performance with the Ag nanoparticles based inks, the S2S printer was mechanically modified based on the specifications needed.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

CLEARSILVER is a solution for replacing ITO through TCF manufacturing by large scale inkjet printing using Ag and ZnO nanoinks.

In addition to their conductivity and transparency, the next generation of TCF must be lightweight, flexible, cost effective and compatible with large scale manufacturing. These requirements seriously limit the use of ITO as transparent conductor because ITO films deposition methods are expensive and time consuming. Besides, they only allow ITO deposition on limited surface areas (< 400 cm2). Finally, ITO films lack of flexibility and indium is a scarce material . The OPV and OLED lighting applications is the first targeted market. The next mid-term step (5 years), after the integration of the technology by these early adopters, will be the flexible displays market. To this aim, we need to improve the printing resolution in order to be totally invisible to the human eye, < 5 µm.

The CLEARSILVER project will open the field of new possibilities for the entire printed electronic value chain. The foreseeable expected impacts are:

• To create new markets for GNK as nanoinks supplier and for KT as electronic printer manufacturer.
• To participate to the development of a competitive European printed electronics (PE) value chain.
• To promote closer collaboration between an ink supplier, an equipment manufacturer and end-users, addressing the full value chain and leading to a competitive advantage in the market introduction of the final products.
• To bring the flexible PE technology from lab to fab.
• To reduce the influence of mineral supply (Indium) on geopolitical conflicts .

The EU offers the best tool to support SMEs, allowing their transition to the industrial stage and enhancing their competiveness. According to GNK and KT business plans, the SME EU funding will accelerate the companies’ organic growth, their sales enhancement and profitability as well as their capacity to respond to market demand on time.

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