Thermally activated delayed fluorescent (TADF) materials are considered as the competitive alternative to traditional fluorescent and noble-metal-based phosphorescent materials due to their high electroluminescence (EL) efficiency and low cost. Solution-processable TADF OLEDs have drawn great research attention and can be potentially applied in both flat-panel displays and lighting sources in the near future. However, the blue light emitting TADF materials with high luminance, satisfying color purity and excellent stability are still rare. Herein, two blue light emitting TADF molecules (CzAC-TRZ, DFAC-TRZ) are designed and synthesized. Due to the modified acridine units by introducing 9-phenylcarbazole and dibenzofuran as σ-groups into the molecular skeletons, CzAC-TRZ, DFAC-TRZ possess high energy states and rigid molecular configuration. Solution-processed OLEDs based on CzAC-TRZ and DFAC-TRZ achieved high EL efficiency with the external quantum efficiency (EQE) up to 11.8% and 11.5%, respectively. Moreover, compared with the analogue emitter (DMAC-TRZ) fabricated control devices, CzAC-TRZ and DFAC-TRZ OLEDs presented lower roll-offs, blue-shift and narrower EL spectra. These results have shown that introducing high energy state building blocks into the donor units via σ bonds offers a promising approach of developing stable deeper blue TADF emitters.

热活化延迟荧光（TADF）材料因其高电致发光（EL）效率和低成本而被认为是传统荧光和贵金属基磷光材料的竞争替代品。可溶液处理的TADF OLED引起了极大的研究关注，并有望在不久的将来应用于平板显示器和光源。然而，具有高亮度，满足色纯度和优异稳定性的发蓝光的TADF材料仍然很少。在此，设计并合成了两个发出蓝色光的TADF分子（CzAC-TRZ，DFAC-TRZ）。由于通过将9-苯基咔唑和二苯并呋喃作为σ-基团引入分子骨架中而修饰的a啶单元，CzAC-TRZ，DFAC-TRZ具有高能态和刚性分子构型。基于CzAC-TRZ和DFAC-TRZ的溶液处理OLED实现了高EL效率，外部量子效率（EQE）分别高达11.8％和11.5％。此外，与模拟发射器（DMAC-TRZ）制成的控制设备相比，CzAC-TRZ和DFAC-TRZ OLED的滚降更低，蓝移和EL光谱更窄。这些结果表明，通过σ键将高能态的结构单元引入施主单元，为开发稳定的深蓝色TADF发射体提供了一种有前途的方法。