Solution processed polymer light emitting diode with vanadium‐oxide doped PEDOT:PSS

We studied the solution processed vanadium pentoxide (V 2 O 5 ) doping effect in PEDOT:PSS for use in hole injection layer (HIL), and as a result, V 2 O 5 doped PEDOT:PSS improved the performance of polymer light‐emitting diode (PLED) significantly. The improvement is related to the increased conductivity of PEDOT:PSS by V 2 O 5 doping. This improvement enhances hole injection into the emission layer, and it will improve the charge balance. The PLED with PEDOT:PSS HIL and super yellow polymer has maximum current and power efficiencies of 12.01 cd A −1 and 9.67 lm W −1 , respectively. On the other hand, the device with V 2 O 5 (10:1) doped PEDOT:PSS indicates the maximum current and power efficiencies of 15.12 cd A −1 and 12.66 lm W −1 , respectively, indicating that the efficiencies increase over 20% compared to the control device. The leakage currents of the PLED decrease to ∼10% of the control PLED. Note also that V 2 O 5 suppressed the diffusion of indium from anode to PEDOT:PSS, and also prevented the acidic damage from sulfate ions of PEDOT:PSS to IZO and active layer.