Highly Efficient Blue Electroluminescence Based on Pyrene‐Imidazole With Donor–π–Acceptor Molecular Structure

ABSTRACT Hybrid local and charge‐transfer (HLCT) states offer an effective pathway for developing efficient blue organic light‐emitting diodes (OLEDs). In HLCT emitters, locally excited (LE) states enhance radiative transitions and photoluminescence quantum yield, while charge‐transfer (CT) states facilitate exciton harvesting via reverse intersystem crossing. Here, we propose an HLCT‐oriented molecular design strategy to achieve efficient blue emission. Pyrene‐imidazole (PyI) was employed as a weak donor and linked to benzoxazole (BO) acceptors through para‐ and meta‐benzene π‐bridges, affording two D–π–A molecules, p‐PyI‐PBO and m‐PyI‐PBO. The π‐bridges strengthen conjugation and stabilize the HLCT state, while the para‐to‐meta linkage transforms a linear “I‐shaped” geometry into a twisted “V‐shaped” configuration, shortening conjugation and modulating donor–acceptor coupling. This structural regulation produces a more balanced LE/CT distribution, suppressing excessive LE character while retaining sufficient CT contribution for efficient exciton utilization. As a result, m‐PyI‐PBO exhibits more favorable excited‐state properties and delivers efficient blue emission with high color purity. Benefiting from its balanced HLCT characteristics and robust photophysical and thermal stability, the nondoped OLED based on m‐PyI‐PBO shows bright blue emission with CIE coordinates of (0.15, 0.13), a maximum external quantum efficiency (EQE m a x ) of 9.52%, and a low roll‐off of 3.36% at 1000 cd m −2 . The doped device further emits deep blue with CIE coordinates of (0.16, 0.06), close to the European Broadcasting Union standard, and achieves an EQE m a x of 13.22% with an exciton utilization efficiency of 79.72%. This work demonstrates that π‐bridge engineering combined with meta‐linkage is an effective strategy for constructing efficient HLCT‐type blue emitters.