Scheme 1. Schematic representation of the supramolecular self-encapsulation strategy for wide-bandgap LCPs. A) Typical molecular model of our supramolecular self-encapsulated LCPs (SMART: Synergistically Molecular Attractor-Repulsor Theory). B) Chemical structures of the model polymer, PHDPF-Cz, together with the controlled polyfluorenes. C) Computer-generated model of PHDPF-Cz: i) axial and ii) lateral views. Schematic diagram illustrating the ideal molecular packing model for a PHDPF-Cz self-assembled superstructure, where the pendent Cz groups self-assemble into a sheath and act as an encapsulated layer to isolate the chain and inhibit the interchain interaction between π-π backbones, similar to previous studies. [47,52,53] The blue rings signify the backbone chain. The red loops indicate the Cz-threaded layers. The yellow arrow represents the 2D charge transport channel. The orange-yellow arrow denotes the penetration path for various gases, which is disrupted by the Cz-threaded layer.

Control of the hierarchical molecular organization of polydiarylfluorenes by synthetic strategies is significant for optimizing photophysical properties as well as the performance of light-emitting devices. Herein, for the suppression of molecular aggregation and enhancement of luminescence efficiency, a series of steric units were introduced into polydiarylfluorenes by copolymerization, with the aim of integrating the advantages of the steric-hindrance effect and of the β-phase. Optical and Raman spectroscopies revealed a β-phase conformation for a polymer copolymerized with spiro[fluorene-9,9'-xanthene] (SFX), with photoluminescence (PL) peaks at 454, 482, and 517 nm. Moreover, the morphological stability and electroluminescence (EL) stability were also improved without compromising the performance of the polymer light-emitting diodes (PLEDs). Furthermore, three steric-hindrance-functionalized copolymers showed significantly decreased thresholds for amplified spontaneous emission (E) and enhanced stability following thermal annealing treatment. These results indicate that steric-hindrance functionalization is a superior approach to improve the overall stability and optoelectronic properties for blue-light-emitting π-conjugated polymers.

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Easily processed, well-defined, and hierarchical uniform artificial architectures with intrinsic strong crystalline emission properties are necessary for a range of light-emitting optoelectronic devices. Herein, we designed and prepared ordered supramolecular spherulites, comprising planar conformational molecules as primary structures and multiple hydrogen bonds as physical cross-links. Compared with serious aggregation-induced fluorescence quenching (up to 70%), these highly ordered architectures exhibited unique and robust crystalline emission with a high PLQY of 55%, which was much higher than those of other terfluorenes. The primary reasons for the high PLQY are the uniform exciton energetic landscape created in the planar conformation and the highly ordered molecular packing in spherulite. Meanwhile, minimal residual defect (green-band) emissions are effectively suppressed in our oriented crystalline framework, whereas the strong and stable blue light radiations are promoted. These findings may confirm that supramolecular ordered artificial architectures may offer higher control and tunability for optoelectronic applications.

Intrinsically flexible polymeric semiconductors are the most potential active candidates in flexible optoelectronics for their solution-processing ability, dynamic programmable mechanical property and excellent optoelectronic behaviour. Flexible optoelectronic, including stretchable film,...

The intrinsically rigid and limited strain of most conjugated polymers has encouraged us to optimize the extensible properties of conjugated polymers. Herein, learning from the hydrogen bonds in glucose, which were facilitated to the toughness enhancement of cellulose, we introduced interchain hydrogen bonds to polydiarylfluorene by amide-containing side chains. Through tuning the copolymerization ratio, we systematically investigated their influence on the hierarchical condensed structures, rheology behavior, tensile performances, and optoelectronic properties of conjugated polymers. Compared to the reference copolymers with a low ratio of amide units, copolymers with 30% and 40% amide units present a feature of the shear-thinning process that resembled the non-Newtonian fluid, which was enabled by the interchain dynamic hydrogen bonds. Besides, we developed a practical and universal method for measuring the intrinsic mechanical properties of conjugated polymers. We demonstrated the significant impact of hydrogen bonds in solution gelation, material crystallization, and thin film stretchability. Impressively, the breaking elongation for P4 was even up to ~30%, which confirmed the partially enhanced film ductility and toughness due to the increased amide groups. Furthermore, polymer light-emitting devices (PLEDs) based on these copolymers presented comparable performances and stable electroluminescence (EL). Thin films of these copolymers also exhibited random laser emission with the threshold as low as 0.52 μJ/cm2, suggesting the wide prospective application in the field of flexible optoelectronic devices.

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A series of solution-processable 4-subsituted diarylfluorene small molecules for violet-blue amplified spontaneous emission and electroluminescence.