Cesium Hydroxide Doped Tris-(8-hydroxyquinoline) Aluminumrnas An Effective Electron Injection Layer In Inverted Bottom-emissionrnorganic Light Emitting Diodes

摘要

We demonstrate highly efficient inverted bottom-emission organic light-emitting diodes (IBOLEDs) by using cesium hydroxide (CsOH) doped tris-(8-hydroxyquinoline) aluminum (Alq_3) as the electron injection layer on indium tin oxide cathode, which could significantly enhance the electron injection, resulting in a large increase in luminance and efficiency. The maximum luminance, current efficiency, and power efficiency reach 21 000 cd/cm~2, 6.5 cd/A, and 3.5 lm/W, respectively, which are 40%-50% higher in efficiency than that of IBOLEDs with cesium carbonate (Cs_2CO_3) doped Alq_3 as the electron injection layer, where the efficiencies are only 4.5 cd/A and 2.2 lm/W. Our results indicate that CsOH doped Alq_3 should be an effective electron injection layer on a wide range of electrodes to fabricate high performance OLEDs.