Posted on 28 Sep 09:27
Last July, we at Ossila had our application for an Innovate UK grant accepted, and started work in September. Now that the project has finished we thought we would share what we worked on.
We set out to anticipate the market, using our knowledge of the area to investigate products that would help people with the next stage of their research. The main areas of investigation were how to aid the transition to mass manufacture in Organic Electronics research, and to determine what tools were needed to aid the latest cutting edge research.
This included research into:
- Flexible substrates and equipment compatibility
- Producing ultra-clean surfaces
- Perovskites and their position in the industry
- Addressing the problems of scale up
Patterned Flexible Substrates
The potential for flexible electronics is one of the benefits that have made organic electronics a hot bed for research. We know it is a proud moment to get your research onto flexible substrates and to demonstrate your work in a futuristic manner. We investigated the costing and feasibility of pre-patterned flexible substrates as a product and apply our approach to affordable patterned ITO substrates to allow more groups to expand onto flexi. Unfortunately, patterned flexible substrates were not economically viable for us to provide in lab-scale quantities at the moment. While we are unable to provide you with the flexible substrates themselves, we will be looking back into this in the future as technologies advance and have developed the rest of the system to be fully flexi compatible.
To investigate other ways we could aid flexi research, we checked the compatibility of our current product range with flexible PET substrates. The Spin Coater has already been shown to work with flexible substrates:
We were also able to use our deposition masks with flexi substrates successfully. Below we show an example of an evaporated high density OFET pattern (the design with the smallest channel width (20um)) onto a PET substrate.
Our investigation into the technicalities of how to encapsulate flexible devices concluded quickly when we found our own Encapsulation Epoxy, previously used only on rigid substrates, was suitable for flexible substrates as well. The epoxy was shown to be suitably malleable to not crack when the substrate was bent.
Producing Ultra-clean Surfaces
The grant funding allowed us to commercialise several products we had been developing, including the UV Ozone Cleaner. The ability to clean the substrates of all organic matter has startling effects on the wetting properties of the substrate. The UV ozone cleaner was developed to be small enough to comfortably sit in fume hoods and glove boxes.
New Inks and Chemicals
Part of the project looked into new materials to determine which would be at the forefront of research in coming years. Our new DPP-DTT polymer was a direct result of this. We found that we were able to create OFET devices showing high mobilities (1-3 cm2/Vs) using our prefabricated substrates. DPP-DTT has also been shown to work as a donor material for photovoltaic applications, with an efficiency increase potentially possible with changes to crystal morphology.
Over the duration of the project it became clear that perovskites were making a large impact on photovoltaic research. We were able to formulate our own perovskite precursor inks, specifically designed for spin coating. Power conversion efficiencies of 13.1% and 11.8% were achieved in our air processing and nitrogen processing inks respectively. Technical details can be found on the product pages (air processing ink, nitrogen processing ink)
Addressing the Problems of Scale Up
Our pre-patterned ITO substrates have provided scientists with access to affordable and convenient substrates without the need to dedicate time making them themselves. To aid those who are looking to scale up their devices we have created a new range of off-the-shelf substrates with dimension of 25 x 75 mm. This will allow those currently using our substrates to transition easily to larger devices while working in the same framework. The range includes 5 designs:
Alongside this, compatible evaporation masks and cover slips have been designed. The complete system approach used in our smaller substrates has also been utilised here for our scale up substrates.
Slot Die Coater
A large part of this project was focused on developing a high throughput coating device. Scale up brings a new set of challenges and certain lab scale preparation techniques stop being appropriate.
While the control offered by spin coating makes it a prime method to fabricate high quality devices in the lab, it is not a mass manufacture technique and has a small upper limit of substrate size (~50 mm2).
Roll-to-roll printing is a high throughput printing technique most notable for being used to print newspapers. In a roll to roll set up, different coating techniques such as blade coating, screen printing and slot-die coating can be used. For coating without a pattern with minimal wastage of ink material, Slot Die Coating is a prime technique.
Scaling up can cause many unexpected problems; a change in deposition technique can cause different morphologies to arise, solution viscosities may become a problem when coating larger areas and so on. It can be difficult, and/or expensive, to be able to deal with these problems before the pilot plant development stage. We wanted to reduce the cost of coating with Roll-2-Roll compatible techniques, and bring it directly into the lab, or even fumehood.
For that reason we have started development of the Ossila small form slot die coater.
A broad range of our existing materials and equipment work with flexible substrates. These include the spin coater, the evaporation masks, and the encapsulation epoxy.
New materials and inks have been developed thus keeping our catalogue relevant to current research.
New tools, the UV Ozone and Slot Die Coater, have been developed along with new consumables to allow for easier upscaling.
We're always keen to get feedback from our customers, particularly at development stage, so if you'd like to discuss any of the project with us or have any suggestions or comments on what you'd like to see next, then get in touch with a member of the Ossila team at firstname.lastname@example.org