Impact of peripheral groups on pyrimidine acceptor-based HLCT materials for efficient deep blue OLED devices

Abstract

Developing high-efficiency deep blue light-emitting materials is vital for organic light emitting diodes (OLEDs) to realize full-color displays. In this paper, we designed and synthesized two D–π–A type deep blue light-emitting materials with hybrid localized charge transfer (HLCT) properties: FlCz and SFCz. They consisted of fluorene/spirofluorene modified pyrimidine planes as acceptors, carbazole as the donor, and phenyl as the bridging group. Both materials showed good solubility and high thermal stability. The non-doped OLED devices based on the two materials showed excellent electroluminescence performance with EQE_max of 6.61% and 5.86%, L_max of 5983 cd m⁻² and 4463 cd m⁻², and CIE coordinates of (0.16, 0.07) and (0.16, 0.08), respectively. In addition, both devices exhibited only a 6% efficiency roll-off at 1000 cd m⁻².