A Solution Processed Flexible Nanocomposite Substrate with Efficient Light Extraction via Periodic Wrinkles for White Organic Light‐Emitting Diodes

A new flexible nanocomposite substrate is reported to enhance the light outcoupling efficiency of white organic light‐emitting diodes (OLEDs). The substrate comprises silver nanowires as electrode and periodic wrinkles as external structures for light extraction. It can outcouple both the waveguide and substrate modes. With the optimized external light extraction structures, white OLEDs based on the nanocomposite substrates show external quantum efficiency (EQE) enhancement factor of 2.34 compared to control devices on indium tin oxide (ITO)/glass, with an EQE of (38.4 ± 2.7)%, a power efficiency of 85.8 ± 2.9 lm W −1 , and a current efficiency of 100.3 ± 7.1 cd A −1 at luminance of 1000 cd m −2 . Moreover, the external wrinkles improve the spectral uniformity over a wide range of viewing angles, which is an important feature for lighting applications. The nanocomposite substrate is fully solution‐processed and thus can potentially lower the manufacturing cost of high‐efficiency flexible OLEDs.