Abstract
In this study, the effects of indium tin oxide (ITO) surface treatment by various inductively coupled plasmas using O 2, CF 4, and CH 4 on the device characteristics of the organic light emitting diodes (OLEDs) consisted of ITO glass/2-TNATA/α-NPD/Alq 3/LiF/Al were investigated. Among the various plasma treatments, the treatment by the CF 4 plasma showed the best OLED device characteristics while the treatment by the CH 4 plasma showed the worst OLED characteristics. The best OLED device characteristics obtained with the CF 4 plasma treatment was believed to be related to the decrease of hole injection barrier by the formation of a thin CF x buffer layer between the ITO and OLED material in the OLED device. Also, it was believed to be related to the decrease of hole injection property by the increase of work function and the decrease of resistance of ITO with the increase of the (O + F)/(In + Sn) ratio and the decrease of the Sn 4+/In ratio on the ITO surface after the CF 4 plasma treatment. The OLED device obtained after the ITO surface treatment by the CF 4 plasma decreased the turn-on voltage from 4.8 to 3.0 V, increased the highest power efficiency from ∼ 0.58 to 1.35 lm/W, and increased the highest luminescence from 29,000 to 50,000 cd/m 2.
Published Version
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