Efficiency enhancement of blue phosphorescent organic light-emitting diodes using mixed electron transport layer

Blue phosphorescent organic light-emitting diodes (OLED) using mixed electron transport layer (ETL) were fabricated with the device structure of ITO/NPB/mCP:Firpic-8%/TPBi:BCP or TPBi:3TPYMB/Liq/Al to observe mixed ETL’s influence on their electrical and optical characteristics. OLED device with mixed ETL of TPBi with BCP or 3TPYMB significantly improved its current efficiency to 30.4 and 34.2cd/A comparing to 19.8cd/A of single ETL with BCP only. We examined mixed ETL’s capability of electron transport and triplet exciton confinement enhancing phosphorescent OLED’s luminance and luminous efficiency.