Omnidirectional reflector based on Ta₂O₅ cylinder-filled IZO mesh structure for flexible and efficient blue TADF top-emission OLEDs

초록

Flexible top-emission organic light-emitting diodes (f-TEOLEDs) with a high aperture ratio canbe used in next-generation wearable electronic applications. However, the advancement off-TEOLEDs is being hindered by their low light extraction and poor mechanical stability. In thisstudy, we introduce an omnidirectional reflector (ODR) consisting of an Ag/SiO2/Ta(2)O(5 )cylinder-embedded indium zinc oxide (IZO) mesh (c-mesh) structure that improves both thelight extraction and mechanical flexibility of TEOLEDs using blue thermally activated delayedfluorescence emitters. The proposed ODR achieved a remarkable reflectance of over 96%,particularly in the transverse-electric mode. Furthermore, the Ta2O5cylinders effectivelycompensated for the diverse void-induced depths in the IZO mesh, significantly reducing theleakage current between the electrode and the organic layers. In addition, the ODR electrodesexhibited outstanding mechanical stability. Moreover, even after being subjected to 2000bending cycles over a 5 mm radius, the device luminance changed by less than 20%. Notably,the proposed f-TEOLEDs with Ag/SiO2/c-mesh electrodes demonstrated superior performance,achieving a low turn-on voltage (2.6 V), high current efficiency (33 cd<middle dot>A(-1)), and powerefficiency of 29.6 lm<middle dot>W-1. Finally, the devices featured a narrow full width at half maximum of27 nm under first-order microcavity effects.

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