A multifunctional dipyrimidylpyridine electron-transporter combined with Ag for robust and efficient organic light-emitting diodes

Abstract The development of state-of-the-art organic light-emitting diode (OLED) displays still faces two unavoidable challenges: lowering power consumption and achieving long operational stability. These difficulties originate largely from the complex multilayer OLED architecture, where several organic/organic and organic/inorganic heterointerfaces critically influence charge injection, carrier balance, and long-term stability. To address these interface-related issues, we designed a multifunctional electron-transport material, DPmPy-DBF1, that enables efficient electron injection when combined with silver (Ag). DPmPy-DBF1 integrates a dipyrimidylpyridine (DPmPy) unit, capable of strong Ag coordination, with a thermally robust dibenzofuran (DBF) unit through a meta-phenylene linker. This design suppresses excessive conjugation, increases conformational diversity, and produces an amorphous thin film with a high triplet energy of 2.9 eV. The material exhibits excellent thermal stability, including a glass-transition temperature of 127 °C, and favorable energy alignment that mitigates electron accumulation at organic/organic interfaces. When doped with Ag, DPmPy-DBF1 demonstrates superior electron-injection ability, as confirmed by UPS analysis and electron-only devices. A green phosphorescent OLED using DPmPy-DBF1 as a hole-blocking, electron-transport, and electron-injection layer achieves a low turn-on voltage of 2.18 V, a maximum EQE of 20.7%, and an extended operational lifetime (LT70 = 6389 h at 1000 cd m−2). These results highlight DPmPy-DBF1 as a promising multifunctional material for next-generation OLEDs.