Peripheral modification of 1,3,5-triazine based electron-transporting host materials for sky blue, green, yellow, red, and white electrophosphorescent devices

Abstract

A systematic comparison of the physical properties and the dual-role (host and electron transport) applications of star-shaped 1,3,5-triazine-based ET-type hosts (T2T, 3N-T2T, 3P-T2T, and oCF3-T2T) with differential peripheral groups was reported. The introduction of N-heterocyclic polar peripheries onto a 1,3,5-triazine core gave evident benefits to the electron injection/transport properties, rendering efficient PhOLEDs with a simpler device configuration feasible. Among these hosts, 3P-T2T can serve both as a promising host and electron-transport material for various Ir-based electrophosphorescence devices. These PhOLEDs configured with the same device structure exhibited low operation voltages with a maximum η_ext of 8%, 15.7%, 16.9%, 16.4% and 10.8% for sky blue (FIrpic), green [(PPy)₂Ir(acac)], yellow [(Bt)₂Ir(acac)], red [(Mpq)₂Ir(acac)] and white [FIrpic + 0.5 wt%(Mpq)₂Ir(acac)], respectively.