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

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-pi-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).