20‐4: Study on the Effect of OLED Device Lifetime Improvement according to Hole Injection Barrier and p‐Dopants

In testing a special anode pretreatment technique to improve the lifetime of fluorescent blue devices, we found that the characteristics of two different blue devices with similar device lifetimes appeared to be significantly different after pretreatment. One device experienced a slight rise in drive voltage after pretreatment, but an increase in efficiency and lifetime, while a dramatic decrease in both. Accompanied by device measurement and analysis, it was found that the cause of lifetime degradation was the formation of a hole injection barrier, which resulted in the reduction of charge accumulation and recombination in the emitting layer. Therefore, it was confirmed that the increase of p‐type doping concentration can overcome the lifetime degradation phenomenon by increasing the hole and also increase the lifetime by lowering the barrier by additional mild plasma treatment of anode.