The ability to tune polymorphs of conjugated polymers affords a robust platform for investigating the processing–structure–property relationship. However, simple and generalizable routes to polymorphs have yet to be realized. Herein, we report a viable meniscus-assisted solution-shearing (MASS) strategy to effectively modulate polymorphs (i.e., polymorphs I and II) of poly­(3-butylthiophene) (P3BT) and scrutinize the correlation between the two different polymorphs and charge transport characteristics. Specifically, polymorph II exists solely in drop-cast P3BT films. Intriguingly, confined shearing of P3BT renders efficient transformation of polymorph II to I. The kinetics of polymorph transformation associated with the changes in molecular packing and thus photophysical properties are elucidated. The resulting organic field-effect transistors reveal a strong correlation of device performance to attained polymorphs and crystal orientations of P3BT. Such polymorph transformation via the convenient MASS technique can be readily extended to other conjugated polymers of interest. This study highlights the robustness of MASS in regulating polymorphs of conjugated polymers to interrogate their interdependence of processing, structure, and property for a wide range of optoelectronic applications.

Conjugated rod−rod block copolymers (BCPs) are important semiconducting materials because they combine the unique microphase-separation characteristics of BCPs with the remarkable optoelectronic properties of conjugated polymers. The ability to tailor the two fundamental phase transitions (microphase separation and crystallization) in BCPs could enable efficient control over their physical and optoelectronic properties. Herein, a set of poly(3-butylthiophene)-block-poly(3-dodecylthiophene) (P3BT-b-P3DDT) BCPs with controlled block ratios are synthesized and the interplay between their microphase separation and cocrystallization is explored by tuning both the intrinsic (i.e., block ratios) and extrinsic factors (i.e., solvent and thermal annealing temperatures). An increased P3BT content, slower solvent evaporation, and higher thermal annealing temperatures favor microphase separation in P3BT-b-P3DDT. Furthermore, the relationship between various P3BT-b-P3DDT crystalline structures and their charge-transport properties is scrutinized. This work elucidates how P3BT-b-P3DDT BCPs undergo microphase separation and crystallization and how these processes can be tailored, strengthening our fundamental understanding of conjugated rod−rod BCP systems.

The ability to rapidly and precisely position semiconducting π-conjugated polymers over a large area is necessary for various device-related applications. However, the investigation into conjugated block copolymer-based patterned materials and devices is somewhat limited. Herein, a robust meniscus-assisted solution printing (MASP) route to highly ordered stripe arrays of conjugated poly(3-butylthiophene)-block-poly(3-dodecylthiophene) (P3BT-b-P3DDT) is reported, and different periodic stripes are correlated to their charge mobilities. The MASP renders the confined evaporation of P3BT-b-P3DDT solution between two nearly parallel plates and deposition into periodic stripes owing to the coffee-ring effect. Remarkably, two types of stripe arrays, namely, large-size stripe arrays and hierarchical arrays comprising small secondary stripes located between neighboring large-size primary stripes are yielded, where their dimension and period can be delicately tailored. Finally, a distinct correlation between various stripe arrays of P3BTb-P3DDT and the corresponding charge mobility is revealed. Conceptually, such convenient production of P3BT-b-P3DDT stripe arrays via MASP can be readily extended to other π-conjugated polymers and diversity of nanomaterials for potential applications in optoelectronic devices.

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The ability to craft the co‐crystallization in conjugated polymer blends represents an important endeavor for the enhancement of charge transport. However, simple and efficient approaches to co‐crystallization have yet to be realized. Herein, for the first time, a robust meniscus‐assisted solution‐shearing (MASS) strategy is reported to achieve co‐crystallization in the poly(2,5‐bis(3‐hexylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT‐C6) and poly(2,5‐bis(3‐decylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT‐C10) blended films, and correlate this co‐crystalline structure to the charge transport properties. The as‐cast PBTTT‐C6/PBTTT‐C10 blends exhibit co‐crystalline or phase‐separated structures influenced by their molecular weights. Interestingly, confined‐shearing of the initial phase‐separated blended solution to MASS produces the formation of their co‐crystallization. The co‐crystallization kinetics accompanied by the chain packing change and optical properties are scrutinized. Finally, the resulting organic field‐effect transistors (OFETs) signify the cocrystal‐facilitated charge transport in the blends. Conceptually, this efficient MASS strategy in rendering the co‐crystallization in conjugated polymer blends can be readily extended to other conjugated polymer blends of interest for a variety of device applications.

The ability to enhance both the solvent and thermal stability of semiconducting π-conjugated polymers is highly desired for various device-related applications. Herein, a series of poly(3-hexylthiophene)-stat-poly[3-(6-hydroxy)hexylthiophene] (P3HT-stat-P3HHT) statistical copolymers with thermally cross-linkable hydroxyl groups is synthesized and their crystalline structures in three different states, solvent and thermal stability for use in organic field-effect transistors (OFETs) are elucidated. Importantly, these initial P3HT-stat-P3HHT thin films in their as-cast state crystallize well in an edge-on orientation. During annealing at 150 °C, these P3HTstat-P3HHT occur cross-linked and retain edge-on orientation with increased crystallinity and ordering. In contrast, after high-temperature annealing at 300 °C, their edge-on orientation is significantly destroyed due to the cross-linking of hydroxyl groups at melted state. The correlation between different P3HT-stat-P3HHT and their charge mobilities is scrutinized. These cross-linked P3HT-stat-P3HHT exhibit good solvent resistance property and improved thermal stability in OFETs. Conceptually, such side-chain functionalization approach to improve the stability of P3HT-stat-P3HHT can be conveniently extended to other conjugated polymers for diverse optoelectronic applications.

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