Date

Place

Room H (Room Hall 1, 1F)
P2. Poster Session II
August 21, 2015 (Friday)
14:00 ~ 15:30

[P2-114]
14:00 ~ 15:30
Title:Improved Stability of Organic Light-Emitting Diodes Using Nickel Oxide Doped PEDOT:PSS
Jiho Sohn, Yongwon Kwon, and Changhee Lee (Seoul Nat'l Univ., Korea)
Abstract: Poly(ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT?:PSS) is one of the most interesting and studied materials in optoelectronic devices for its high conductivity, high transparency in the visible range and high workfunction. It has been widely used as hole injection layer (HIL) on top of the anode in organic light-emitting diodes (OLEDs). However, PEDOT?:PSS have several limitations especially that the nature of its acidity affects the organic/inorganic interface, leading to device failure. Here, we have investigated the effect of sol-gel nickel-oxide (NiOx) doping in PEDOT:PSS (PEDOT:PSS:NiOx), specifically in terms of the OLED device stability.NiOx thin films are p-type and transparent semiconductor with a band gap energy in the range of 3.6-4.0eV. The sol-gel processed NiOx has a deep LUMO level above 2eV which can be stable in air without being oxidized. Therefore, we have adopted sol-gel NiOx doped in PEDOT:PSS to improve OLED device stability. The effect of NiOx doping in PEDOT:PSS have been demonstrated using green phosphorescent emitter?with different NiOx doping concentrations. The device stability was measured through operation lifetime, fixing the initial luminance at 2000cd/m2 and supplying constant current to each device. The device with 10:1 volume ratio of PEDOT:PSS:NiOx exhibited extrapolated half-lifetime (LT50) of 14.3 hours, improving the operation lifetime nearly 200% compared to that of reference PEDOT:PSS (LT50 = 7.5 hours).
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