Light extraction from organic light emitting diodes (OLEDs)

Abstract Organic light emitting diode (OLED) technology continues to make strides, particularly in display technology, with costs decreasing and consumer demand growing. Advances are also seen OLED solid state lighting (SSL) though broad utilization of this is lagging. This situation has prompted extensive R&D achieve high-efficiency SSL devices at cost-effective fabrication. Here we review the advances challenges enhancing forward outcoupling from OLEDs. Light conventional bottom-emitting OLEDs (through a transparent anode) typically ?20%, largely due external losses, i.e., substrate waveguide modes, internal modes between metal cathode anode/substrate interface, surface plasmon-polariton cathode/organic interface. We address these major photon loss paths, presenting various extraction approaches. Some approaches devoid structures; they include replacing commonly used ITO anode, manipulating refractive index and/or organic layers, evaluating emitters preferential horizontal transition dipoles. Other use structures such as microlens arrays, scattering layers patterned substrates, well substrates buried that planarized by high layers. A maximal quantum efficiency 78% was reported for white hemispherical lens extract mode. on flexible addressed, latter become increasing interest foldable displays decorative lighting, plastic being evaluated biomedical, wearable, automotive applications.