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Updated: Jun 1, 2026
Development of Efficient OLEDs from Solution Deposition
Published on: November 4, 2022
Creating a pseudometallic state of K+ by intercalation into 18-crown-6 grafted on polyfluorene as electron injection
Hsin-Hung Lu1, Yun-Sheng Ma, Neng-Jye Yang
1Chemical Engineering Department, National Tsing-Hua University, Hsinchu 30041, Taiwan, ROC.
Abstract:
Polymer light-emitting diodes (PLEDs) suffer from inadequate lifetimes because of the use of environmentally sensitive metals as the cathodes. We present the use of water/methanol-soluble polyfluorene grafted with 18-crown-6 chelating to K(+) as the electron-injection layer (EIL) for deep-blue-emission PLEDs, allowing the use of environmentally stable Al as the cathode since electron donation from the 18-crown-6 can reduce K(+) to a stable "pseudometallic state", enabling it to act as an intermediate step for electron injection. Furthermore, when poly(ethylene oxide) was blended into the EIL to provide hole blocking (HB), the device exhibited the highest performance reported to date for a deep-blue-emission PLED based on a conjugated polymer as the emitting layer, with a brightness of 54,800 cd/m(2) and an external quantum efficiency of 5.42%. The use of such an EI-HB layer opens a broad avenue leading toward industrialization of PLEDs.
