Felix Widdascheck, Daniel Bischof and Gregor Witte developed a robust method to prepare air-stable molecular contact primer layers allowing to reduce hole injection barriers of printable silver electrodes into organic semiconductors.
Contact engineering is an important issue for organic electronics as it allows to reduce charge carrier injection barriers. While the use of molecular contact primer layers was demonstrated in many concept studies for single crystalline model substrates, the processability of electrodes and their robustness in real devices must also be considered. Although silver electrodes can be printed using silver ink, their low work function and sensitivity to oxidation severely limits their use for printable organic electronics.
In this study Prof. Witte and his coworkers demonstrate that F6TCNNQ monolayers provide a reliable approach to engineer high work function silver electrodes, which is examined for Ag(111) as well as polycrystalline and silver ink substrates. Notably, upon multilayer growth, a pronounced intercalation of silver into the molecular adlayer occurs, yielding thermally stabilized organometallic interphases extending over the entire adlayer. It is shown that heating allows their controlled desorption leaving behind a well-defined monolayer that is further stabilized by additional charge transfer. Such primer layers enhance the work function to 5.5-5.6 eV and can even withstand air exposure but show no interdiffusion into subsequently deposited p-type organic semiconductor, hence validating their use for organic electronic devices.
For further information, please see the press release by the Philipps-Universität Marburg (in German).
F. Widdascheck, D. Bischof, G. Witte
Engineering of Printable and Air-Stable Silver Electrodes with High Work Function using Contact Primer Layer: From Organometallic Interphases to Sharp Interfaces
Adv. Funct. Mater. (2021) DOI:10.1002/adfm.202106687
Prof. Dr. Gregor Witte
SFB project A2
Tel.: 06421 28-21384