Carbazole and dibenzo[b,d]furan-based hole transport materials with high thermal stability

Abstract

High thermal stability is of pivotal significance for hole transport materials (HTMs) owing to thermal evaporation and device operation stability requirements. In this study, two new HTMs, namely FCzTPA and FCzDPNA, were developed by using easily accessible carbazole/dibenzo[b,d]furan derivatives. The rigid structures bring about excellent thermal stability, with a decomposition temperature (T_d) of up to 400 °C and glass transition temperature (T_g) above 190 °C. Moreover, benefiting from the twisted spatial configuration and constituent units, they both exhibit suitable triplet energy levels (E_T = 2.56, 2.74 eV). When hosting red phosphorescent organic light emitting diodes (PhOLEDs), the FCzTPA-based device shows a turn-on voltage (V_on) of 3.4 V and the maximum external efficiency (EQE_max) of 18.61%, indicating that the synthetic compounds are potential building blocks for highly efficient OLEDs.