Outcoupling-Enhanced Flexible Organic Light-Emitting Diodes on Ameliorated Plastic Substrate with Built-in Indium–Tin-Oxide-Free Transparent Electrode
journal contributionposted on 28.07.2015, 00:00 by Heng-Yang Xiang, Yan-Qing Li, Lei Zhou, Hao-Jun Xie, Chi Li, Qing-Dong Ou, Lin-Sen Chen, Chun-Sing Lee, Shuit-Tong Lee, Jian-Xin Tang
Enhancing light outcoupling in flexible organic light-emitting diodes (FOLEDs) is an important task for increasing their efficiencies for display and lighting applications. Here, a strategy for an angularly and spectrally independent boost in light outcoupling of FOLEDs is demonstrated by using plastic substrates 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. This paradigm for light outcoupling enhancement in ITO-free FOLEDs offers additional features and design freedoms for highly efficient flexible optoelectronics in large-scale and low-cost manufacturing without the need for a high-refractive-index plastic substrate.