Ultrathin Fully Printed Light‐Emitting Electrochemical Cells with Arbitrary Designs on Biocompatible Substrates

Abstract Organic electronic devices are often highlighted in terms of cost‐efficient solution processing and potential printability. However, few studies are reporting truly full‐solution‐processed devices taking into account the electrodes as well as all other layers. This results in a production method that only partially benefits from the cost efficiency of solution processing and that still depends on costly and elaborate techniques like evaporation and/or lithography. This lack of knowledge is addressed by presenting a truly fully printed light‐emitting electrochemical cell on ultraflexible parylene C substrates usable for conformable electronics. All device parts are fabricated by industrial relevant printing‐techniques under ambient atmosphere. Inkjet printing is used for the structuring of the device layout and is therefore able to implement and create arbitrary designs. Further layers are produced by blade coating which is well suited for the coating of large areas. The devices show stable operation at a luminance higher than 100 cd m⁻² for 8.8 h, can reach a maximum brightness of 918 cd m⁻², and exhibit a turn‐on time of 40 s to reach 100 cd m⁻². Moreover, biocompatible and biodegradable materials are utilized to allow potential applications in life science and bioelectronics.