B5: Nirbhika Nandakumar
After completing my masters in organic and molecular electronics, I knew that I wanted to remain in this field, given its significance in our quest for sustainability and also for innovations in the biomedical field that will improve the quality of life. I was excited to have found the position in the RTG 2767 within the field of organic electronics. I am very happy that the RTG gives me the opportunity to connect with my peers in adjacent fields giving us the opportunity to exchange ideas and collaborate. My research will focus on transparent metallic electrodes for OLEDs.
Supervisors: Caroline Murawski, Alexander Eychmüller
Organic light-emitting diodes (OLEDs) have properties that give them immense potential for various applications: They are capable of producing homogeneous light emission from large areas, can be structured to micron-sized pixels with high resolution, and can be fabricated on various substrates including flexible plastic films. These properties make OLEDs highly desirable candidates for flexible displays, wearables and biological applications, where conformability of electronic devices to soft tissue is required. However, the fabrication of flexible substrates with encapsulation layers that are strong enough to protect organic electronic devices from ingress of oxygen and moisture for months or even years is very challenging . In this context, 6 μm thin conformal barrier layers of parylene-C and metal oxides fabricated via atomic layer deposition may yield extremely flexible, water-resistant OLEDs .
In order to enable charge injection into flexible OLEDs, bendable, transparent and highly conductive electrodes are required. Until now, most transparent electrodes used in OLEDs are based either on transparent conductive oxides, which are brittle and require high fabrication temperatures, or on thin metals, which provide only low transparency. Other possibilities include carbon-based electrodes, which are complicated to process, and polymer-based electrodes, which suffer in terms of conductivity and transparency.
Recently, 2D metal aerogels have been synthesized via phase-boundary gelation . The aerogels are extremely thin (4 – 15 nm), conductive (sheet resistance 56 Ω/□), and highly transparent (up to 97 %), thus, making them ideal candidates to be used as electrodes for flexible OLEDs.
 Eun Gyo Jeong, Jeong Hyun Kwon, Ki Suk Kang, So Yeong Jeong & Kyung Cheol Choi: Journal of Information Display 21 (2020), p 19
 Keum, C. Murawski, E. Archer et al: Nature Communications 11 (2020), p 6250
 Hiekel, S. Jungblut, M. Georgi, & A. Eychmüller: Angew. Chem. Int. Ed. 59 (2020), p 12048