Non‐Doped Blue AIEgen‐Based OLED with EQE Approaching 10.3 %

Abstract Aggregation‐induced emission (AIE) luminogens (AIEgens) are attractive for the construction of non‐doped blue organic light‐emitting diodes (OLEDs) owning to their high emission efficiency in the film state. However, the large internal inversion rate ( k IC (Tn) ) between high‐lying triplet levels (T n ) and T n‐1 causes a huge loss of triplet excitons, resulting in dissatisfied device performance of these AIEgens‐based non‐doped OLEDs. Herein, we designed and synthesized a blue luminogen of DPDPB‐AC by fusing an AIEgen of TPB‐AC and a DMPPP, which feature hot exciton and triplet‐triplet annihilation (TTA) up‐conversion process, respectively. DPDPB‐AC successfully inherits the AIE feature and excellent horizontal dipole orientation of TPB‐AC. Furthermore, it owes smaller k IC (Tn) than TPB‐AC. When DPDPB‐AC was applied in OLED as non‐doped emitting layer, an outstanding external quantum efficiency of 10.3 % and an exceptional brightness of 69311 cd m −2 were achieved. The transient electroluminescent measurements and steady‐state dynamic analysis confirm that both TTA and hot exciton processes contribute to such excellent device performance. This work provides a new insight into the design of efficient organic fluorophores by managing high‐lying triplet excitons.