Starburst-type triarylphosphine oxide trimers forming a stable amorphous n-type layer in solution-processed multilayer OLED

摘要： Novel starburst-type triphenylphosphine oxide trimers PO-1 and PO-2 were synthesized aimed at application as an electron-transporting material for multilayer organic light-emitting diodes (OLEDs). They showed high glass transition temperatures (Tg; 175 and 205 (cid:1)C, respectively) and high lowest triplet energies (T1; 2.81 and 2.78 eV, respectively). Their high solubility in 2-propanol allowed us to fabricate multilayer OLEDs by solution processing, and a double-emitting layer OLED consisting of poly(9-vinylcarbazole)-based p-type and PO-1-based n-type layers doped with a phosphorescent material (FIrpic) showed efficient sky-blue electroluminescence with a maximum external quantum efficiency of 9.33%.