High-Performance Flexible Organic Light-Emitting Diodes Using Embedded Silver Network Transparent Electrodes

Because of their mechanical flexibility, organic light emitting diodes(OLEDs) hold great promise as a leading technology for display and lighting applications in wearable electronics. To date, the most commonly used transparent conductive electrode(TCE), indium-tin-oxide(ITO), limits the further development of high-performance flexible OLED technology due to its inherent shortcomings such as brittleness, material scarcity, and a low-throughput deposition process. The development of flexible OLEDs requires high-quality transparent conductive electrodes with superior bendability and roll-to-roll manufacturing compatibility to replace indium tin oxide(ITO) anodes.Here, we present a flexible transparent conductor on plastic with embedded silver networks which is used to achieve flexible, highly power-efficient large-area green and white OLEDs. By combining an improved outcoupling structure for simultaneously extracting light in waveguide and substrate modes and reducing the surface plasmonic losses, the bottom-emitting flexible white OLEDs exhibit a power efficiency of 106 lm W-1 at 1000 cd m-2, and the transparent flexible white OLEDs exhibit a power efficiency of 112 lm W-1 at 1000 cd m-2. These results represent an exciting step toward the realization of ITO-free, high-efficiency OLEDs for using in a wide variety of high-performance flexible applications.In the other hand, Enhancing light outcoupling in flexible organic light-emitting diodes(FOLEDs) is an important task for increasing their efficiencies for display and lighting applications. Thus, a strategy for an angularly and spectrally independent boost in light outcoupling of FOLEDs is demonstrated by using the embedded silver networks with a low refractive index, consisting of a bioinspired optical coupling layer and a transparent conductive electrode composed of a silver network. The good transmittance to full-color emission(> 94 % over the whole visible wavelength range), ultralow sheet resistance to carrier injection(< 5 Ω sq-1), and high tolerance to mechanical bending of the ameliorated plastic substrates synergistically optimize the device performance of FOLEDs. The maximum power efficiencies reach 47, 93, 56, and 52 lm W-1 for red, green, blue, and white emissions, which are competitive with similarly structured OLEDs fabricated on traditional indium-tin-oxide(ITO) glass.The flexible device presented in this work has the potential to achieve an even higher efficiency if all the device parameters and optical structures are continuously optimized to reduce the energetic and outcoupling losses during electron-photon conversion. The approach demonstrated here opens up the opportunity to other large-scale roll-to-roll fabrication technologies for wearable optoelectronics with high performance and low manufacturing and materials cost.