The manufacture of robust ultra‐deep‐blue polymer with an intrinsic stretchability is an extreme challenge toward fabricating flexible light‐emitting optoelectronic devices. As a key precondition for the realization of the intrinsically stretchable behavior, easily interchain slippages also cause the formation of intermolecular excited states, which is negative to the color purity and the emission efficiency of blue‐emitting film and devices. Herein, a series of π‐interrupted‐conjugated alternating polymers with a robust ultra‐deep‐blue emission and intrinsically stretchable properties are demonstrated. Interestingly, the model polymers (P4, P6, and P8) present stable ultra‐deep‐blue emission with an extremely high efficiency of ≈90% and a Commission internationale de l'éclairage (CIE) coordinates of (0.15, 0.06) in solid‐state, attributed to the excellent singlet excitonic behavior without any obvious polaron formation. More importantly, significantly different to rigid π‐conjugated polymers, the model P8 film displays an efficient deep blue emission even under a tensile rate of ≈15%, associated with the densely interchain entanglement and interpenetration. Finally, preliminary P8‐based polymer light‐emitting diodes also show a stable ultra‐deep‐blue emission with a CIE of (0.15, 0.06). All results above confirm the effectiveness of the π‐interrupted‐conjugated strategy to construct a robust deep‐blue polymer with an excellent intrinsic stretchability, which is a great potential for applying in flexible light‐emitting devices.

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Organic conjugated molecules with a rigid rod‐like π‐backbone structure automatically and easily self‐assemble into an anisotropic nanostructure. However, supersecondary structures obtained from the hierarchical secondary self‐assembly of nanostructures have rarely been reported for non‐amphiphilic conjugated molecules. Here, a nanowire architecture as a supersecondary structure from an ultra‐deep‐blue fluorene‐based conjugated molecule (FCz‐C8‐Am) to improve the emission efficiency and stability is reported. In significant contrast to the four reference molecules, the FCz‐C8‐Am molecules grow into soft nanowires and further self‐assemble into a series of nanowire architectures in the gelation process. This is associated with the synergistic effect of the hydrogen bonds among the amide units, pendant π–π stacking interactions between pendant Cz units, and appropriate soft steric interaction among side‐chains, which are the three design requirements for preparing these nanowire architectures. Interestingly, this supersecondary architecture of FCz‐C8‐Am has a stable ultra‐deep‐blue emission, with an efficiency of ≈77% and a Commission Internationale de L'Eclairage (CIE) value of (0.16, 0.06) in the solid state. These findings provide a profound understanding of the relationship between the inherent molecular structure, supramolecular interaction, and supersecondary nano‐architecture, offering useful information for the development of new functional optoelectronic materials.

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