ABSTRACT Hot‐exciton materials capable of high‐lying triplet‐to‐singlet reverse intersystem crossing offer great potential to simultaneously achieve high exciton utilization and ultrafast radiative decay. Nevertheless, the rational molecular design of dual‐functional emitters for both efficient electroluminescence and fast radioluminescence remains challenging. Here, a novel phenanthroimidazole‐anthracene‐based emitter PI‐An‐PF was designed and synthesized via a facile molecular engineering strategy. The incorporation of anthracene not only constructs a favorable high‐lying excited‐state energy landscape to activate the efficient hot‐exciton pathway, but also suppresses intermolecular aggregation and enhances x‐ray stopping power, endowing the molecule with dual optoelectronic functionalities. Systematic photophysical measurements, including temperature‐dependent and atmosphere‐dependent transient spectroscopy, corroborate the dominant hot‐exciton emission mechanism. Benefiting from the hybrid local and charge‐transfer (HLCT) feature and favorable horizontal dipole orientation, the optimized non‐doped OLEDs achieve high‐efficiency deep‐blue emission with a maximum EQE of 7.07% and negligible efficiency roll‐off. Meanwhile, PI‐An‐PF exhibits an ultrafast RL decay lifetime of 1.49 ns and a low x‐ray detection limit of 305 nGy s. This work reveals the unique advantages of anthracene‐modified phenanthroimidazole hot‐exciton materials and provides a feasible molecular design strategy for multifunctional optoelectronic materials toward display and radiation detection application.
Zhao et al. (Tue,) studied this question.