A novel lactam-based AIE building block for high-performance deep-blue electroluminescent materials

Abstract

Developing high-performance deep-blue organic light-emitting diodes (OLEDs) requires the emitters to achieve a good balance among emission color, exciton utilization efficiency, and photoluminescence quantum yield (PLQY) in solid films. Herein, we report a new deep-blue emissive building block, abbreviated as PADP, which exhibits aggregation-induced emission (AIE) characteristics. Its solid-state emission peak is located at 408 nm, effectively filling a gap in AIE-based blue-emitting frameworks within this spectral region. Studies on substitution at the 6-position of PADP demonstrate that the introduction of strong electron-donating groups can effectively modulate the S₁ excited-state properties, promote the formation of hybridized local and charge-transfer (HLCT) states, and activate hot-exciton channels in the electroluminescence process to harvest high-lying triplet excitons. Among these derivatives, PADP-TPA with triphenylamine modification exhibits a maximum external quantum efficiency (EQE) of 9.2% in a deep-blue OLED with CIE coordinates of (0.154, 0.049), representing state-of-the-art performance for OLEDs based on deep-blue AIE fluorescent materials. These results not only elucidate the structure–property relationships of the PADP building block but also demonstrate its significant potential for the design of highly efficient deep-blue OLED emitters.