Amruth's Slot-Die Secondment

Posted on Tue, Feb 20, 2018 by Ashley Wong
Amruth is a PhD student currently based at Department of Molecular Physics in the Lodz University of Technology, Poland, as a part of the Excilight Innovative Training Network (ITN) programme. Lodz University of Technology Logo

As an industrial partner in the EU-funded Excilight Innovative Training Network (ITN) Programme, Ossila recently hosted Amruth, a PhD student who was on secondment with us from November 2017, and primarily worked with our Slot-Die Coater. As his secondment with Ossila drew to a close earlier this month, we thought it would be great for him to share his experiences and some of his research findings with you!


Excilight PhD student, Amruth, with his finished OLED device
Amruth with his finished OLED device.


What were you working on before joining Excilight?

I worked in the field of printed electronics for over 5 years, carrying out industrial R&D in India. However, I had a desire to conduct more innovative scientific research and publish academic articles, which is why I chose to pursue a PhD with the Excilight Training Network.


How has your Excilight experience been so far?

I am based at the Technical University of Lodz (TUL) in Poland, where for the past 2 years I mainly worked on inkjet printing of OLEDS, printing light-emissive materials and fabricating devices. Having not specifically worked with OLEDs previously, this was a slightly new experience where the underlying physics was different, but the engineering was similar (to my time in printed electronics). Poland is beautiful! The people are friendly and welcoming, everything is so organised and I found it easy to assimilate. Having collaborated with TUL back when I worked in India, it was exciting to be working there myself. Coincidentally, I also used quite a few Ossila products in TUL before coming here for my secondment - namely the pre-patterned substrates, deposition masks for OLEDs, and other materials - so it has been nice getting to see what goes on behind-the-scenes! 


Slot-Die Coater | Ossila
A device being coated by the Ossila Slot-Die Coater.

What have you been working on during your secondment at Ossila?

Initially, my time was spent getting to know everything about the Ossila Slot-Die Coater and the techniques, e.g. basic parameters, how it prints, etc. Unlike the larger alternatives I've used before, Ossila's Slot-Die Coater has very little ink wastage due to its compact size. For example, just 2-3ml of ink allows me to obtain about 20-30 coatings, and I don't need any extra ink to get the process started, so it saves me time and money. Because it is small, I can easily move it around the lab, and I think researchers who are looking for ways to make quick small batches of prototypes will enjoy using it!


Ossila Slot-Die Coater being used in the lab by Excilight PhD student, Amruth
Amruth using Ossila's Slot-Die Coater in the lab.


Since then, I've been optimising the conditions of Ossila's Slot-Die Coater for producing the PEDOT:PSS and fluorescent green light-emitting layer for OLED applications. By tuning the various parameters of the slot-die coater, it was possible to obtain PEDOT:PSS film with thicknesses of 30 to 60 nm and a light-emitting layer with thicknesses of 50 nm to 70 nm. The thicknesses of these layers are adequate for the fabrication of high-quality OLEDs. With a device structure of: Glass/ITO/PEDOT:PSS (slot-die coated)/fluorescent light-emitting layer (slot-die coated)/LiF/Aluminum, I fabricated OLEDs with a brightness of 400cd/m2 and an efficiency of 1.5cd/A. The device area is free from pinholes, and light emission was uniform across the device, as it was fully emitting light. I believe that by further optimising the slot-die process, one can improve device performances.


Slot-Die Coater | Ossila
Slot-die coating of the fluorescent polymer layer.


What are some of the things you've learned whilst working at Ossila?

People here have been very friendly and open to helping me whenever I have any questions. I like the structure of Ossila's weekly meetings - they start out with someone sharing what they've learned from a book on business/management, and then carrying on with important updates from different departments. Also, I've now spent a considerable amount of time working on slot-die coating, and that adds to my experience in printable electronics - nearly a decade's worth of knowledge now.


Tell us about your most memorable moment here!

That would be the office Secret Santa & Christmas Dinner - it was my first time celebrating Christmas in the West, so it was a very interesting experience!


Finally, what advice would you give to someone who is wanting to pursue a PhD in this field?

Printed electronics is a promising field that hopes to integrate many everyday electronics (e.g. screen display, solar cells, antennas, battery, sensors, and electronic circuits) on to surfaces like textiles, plastic films, paper, and metal. This technology opens the door to create new products that are cost-effective by adapting printing technology - meaning that there will be opportunities for building business start-ups. However, because there are still challenges to be addressed in terms of processing techniques and materials science, this means that there are many interesting topics and opportunities to be studied in-depth in a PhD thesis. Lastly, pursuing a PhD  in this field has enabled me to explore new things, developed my ability to understand and solve scientific problems, and made me a better communicator. 


Author: Ashley Wong

Hailing from a Psychology background, Ashley has an MSc in Organizational/Work Psychology from the Sheffield University Management School. Prior to joining Ossila, Ashley worked with two multi-national organizations, researching emotional labour in the life insurance industry. In 2017, she successfully led the process of writing & applying for a prestigious Institute of Physics Business Innovation Award, which resulted in Ossila winning its first-ever industrial award.