Development of a highly efficient, strongly coupled organic light-emitting diode based on intracavity pumping architecture

We report a highly efficient polariton organic light-emitting diode (POLED) based on an intracavity pumping architecture, where an absorbing J-aggregate dye film is used to generate polariton modes and a red fluorescent OLED is used for radiative pumping of emission from the lower polariton (LP) branch. To realize the device with large-area uniformity and adjustable coupling strength, we develop a spin-coating method to achieve high-quality J-aggregate thin films with controlled thickness and absorption. From systematic studies of the devices with different J-aggregate film thicknesses and OLED injection layers, we show that the J-aggregate film and the pump OLED play separate roles in determining the coupling strength and electroluminescence efficiency, and can be simultaneously optimized under a cavity design with a good LP-OLED emission overlap for effective radiative pumping. By increasing the absorption with thick J-aggregate film and improving the electron injection of pump OLED with Li2CO3 interlayer, we demonstrate the POLED with a large Rabi splitting energy of 192 meV and a maximum external quantum efficiency of 1.2%, a record efficiency of POLEDs reported so far. This POLED architecture can be generally applied for exploration of various organic materials to realize novel polariton devices and electrically pumped lasers.