Highly transparent and stretchable organic light-emitting diodes with ultrathin metal films as double electrodes

Organic light-emitting diodes (OLEDs) with both high transparency and stretchability are of importance for next-generation wearable and deformable displays, which have not been studied in depth. In this work, highly flexible and transparent OLEDs (TrOLEDs) are achieved by using ultrathin metal films as both anode and cathode to fabricate stretchable TrOLEDs (S-TrOLEDs) based on a wrinkling strategy. The TrOLEDs show a transmittance value of 73% at 550 nm and a negligible micro-cavity effect with near Lambertian emission characteristics at a wide angle of view. Furthermore, almost symmetric electroluminescent properties are obtained from the anode and cathode, which is important for dual-side display. Two-dimensional S-TrOLEDs with random wrinkles show 50% stretchability and retain 80% of their initial luminance after 200 cycles of stretching. The effect of random wrinkles on the transmittance of S-TrOLEDs is researched and the transparency losses of the device are analyzed deeply. We hope that this work is meaningful for promoting the development of S-TrOLEDs in the display industries.