Polycyclic TADF Emission Layers for Efficient, Long-Life Displays

The patent modifies the molecular structure of TADF compounds by introducing specific polycyclic frameworks (such as dibenzofuran, dibenzothiophene, carbazole units) and adjusting substituent groups to optimize the singlet-triplet energy gap (ΔEST) and HOMO-LUMO energy levels. These parameter changes in molecular structure directly improve both emission efficiency through enhanced radiative decay rates and lifespan through improved material stability and reduced degradation pathways

The emission layer employs composite material systems combining host materials (e.g., mCP, TCTA, TAPC) with dopant TADF compounds (e.g., compounds 1-10 with specific polycyclic structures). This composite approach allows the host to provide structural stability and charge transport while the dopant provides efficient TADF emission, achieving synergistic improvement in both emission efficiency and device lifespan

The TADF compounds are designed with segmented molecular architectures consisting of distinct functional units: polycyclic core structures (dibenzofuran, dibenzothiophene, carbazole) that provide rigidity and stability, electron-donating groups (amine, carbazole) that raise HOMO levels, and electron-withdrawing groups (cyano, carbonyl) that lower LUMO levels. This segmentation allows independent optimization of each unit's function while maintaining overall molecular stability and emission performance

The patent introduces localized functional groups at specific positions on the polycyclic framework (e.g., cyano groups at para positions, carbazole units at ortho positions) to create local electronic properties that enhance charge injection and emission efficiency without compromising the global structural stability of the molecule. This local quality modification enables precise control over emission characteristics while maintaining material lifespan