The molecular configuration optimization is crucial for accurately controlling the intermolecular interactions of organic conjugates. Herein, with the purpose to integrate spherical geometry and optoelectronic properties, the first phosphine oxide (PO) bridge‐ring host 5,10‐[1,2]benzenophosphanthrene 5,10‐dioxide (BPAO2) with phosphorus as bridgehead atom is demonstrated. The sphere‐like paddle‐wheel configuration of BPAO2 gives rise to the highly ordered layer‐by‐layer packing mode, owing to its single molecular orientation, which provides the weak π–π interactions in each layer and hydrogen bond networks between layers. These limited but sufficient interactions are preserved in dilute solution and vacuum‐evaporated film, balancing the charge transportation and the quenching suppression. As consequence, its blue thermally activated delayed fluorescence (TADF) diodes achieve the record‐low turn‐on voltage as 2.3 V, which is remarkably below blue photon energy (≈2.6 eV), and the power efficiency up to ≈70 lm W−1. This work demonstrates the great potential of hetero bridge‐ring systems for optoelectronic applications.

Aramid fiber-reinforced rubber composites (AFRCs) have attracted considerable attention due to their excellent mechanical properties. These mechanical properties provide the composites with a certain degree of anisotropy due to the fiber orientation distribution (FOD) in the AFRCs, thereby allowing them to flexibly meet requirements based on different scenarios. However, the quantitative determination of FOD in AFRCs continues to be a challenge. In this study, the triple ion-beam cutting technique was proposed to obtain high-quality polished cross-sections of the AFRCs. An image processing technique was used to separate the rubber matrix and the fiber in the optical micrograph. The fiber orientation information was extracted based on the shape of the fiber section. The FODs of the AFRCs were described using the probability function. Finally, the mechanical property was evaluated using a 2D finite element analysis. The agreement between the experimental and numerical results validated the effectiveness of the proposed method.

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