A substrateless, flexible, and water-resistant organic light-emitting diode

Changmin Keum,Malte C Gather,Andreas Mischok,Emily Archer,Caroline Murawski,Seonil Kwon

doi:10.1038/s41467-020-20016-3

Abstract

Despite widespread interest, ultrathin and highly flexible light-emitting devices that can be seamlessly integrated and used for flexible displays, wearables, and as bioimplants remain elusive. Organic light-emitting diodes (OLEDs) with µm-scale thickness and exceptional flexibility have been demonstrated but show insufficient stability in air and moist environments due to a lack of suitable encapsulation barriers. Here, we demonstrate an efficient and stable OLED with a total thickness of ≈ 12 µm that can be fully immersed in water or cell nutrient media for weeks without suffering substantial degradation. The active layers of the device are embedded between conformal barriers formed by alternating layers of parylene-C and metal oxides that are deposited through a low temperature chemical vapour process. These barriers also confer stability of the OLED to repeated bending and to extensive postprocessing, e.g. via reactive gas plasmas, organic solvents, and photolithography. This unprecedented robustness opens up a wide range of novel possibilities for ultrathin OLEDs.

Highlights

Despite widespread interest, ultrathin and highly flexible light-emitting devices that can be seamlessly integrated and used for flexible displays, wearables, and as bioimplants remain elusive
Our flexible Organic light-emitting diodes (OLEDs) are composed of two ≈6 μm thick thin-film encapsulation (TFE) barrier films sandwiching the actual device, which consists of a semitransparent metal anode, the active organic layers, and a highly reflective metal cathode (Fig. 1a)
Organic semiconductors degrade in the presence of hard radiation, high energy particles and high process temperatures. This makes the use of common high-throughput physical vapor and plasma-assisted deposition processes on top of OLED stacks problematic and renders them less preferable for the manufacture of TFE barriers on OLEDs

Summary

Introduction

Ultrathin and highly flexible light-emitting devices that can be seamlessly integrated and used for flexible displays, wearables, and as bioimplants remain elusive. The active layers of the device are embedded between conformal barriers formed by alternating layers of parylene-C and metal oxides that are deposited through a low temperature chemical vapour process These barriers confer stability of the OLED to repeated bending and to extensive postprocessing, e.g. via reactive gas plasmas, organic solvents, and photolithography. The development of mechanically flexible OLEDs has inspired smartphones and TVs with curved displays and first products with simple foldable displays are entering the market Beyond their use in displays, flexible OLEDs enable a multitude of promising new applications in which conformal integration or resilience against mechanical deformation are essential, e.g., for wearable and biomedical devices[11,12,13].

Methods

Results

Conclusion