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Tailoring the crystal orientation of donor–acceptor (D–A) copolymers is vital for boosting the performance of optoelectronic devices. Despite recent advances in controlling the crystal orientation of D–A copolymers in films, the investigation into their aggregates in solution and the correlation between the solution aggregates and solid‐state crystal orientation has been limited. Herein, an effective solvent additive strategy is reported for tuning solution aggregates and the consequent solid‐state structures of poly{[N,N'‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (P(NDI2OD‐T2)). Specifically, the addition of 1‐decanethiol (10‐thiol) to the P(NDI2OD‐T2) chloroform solution promoted the aggregation of P(NDI2OD‐T2) chains because of the improved planarization of the backbones, which changed their crystal orientation in the film from coexisting edge‐on and face‐on to dominant edge‐on when produced by drop‐casting. The mechanism of this crystal orientation transformation is elucidated based on the interaction between 10‐thiol and the side chains of P(NDI2OD‐T2). The optical properties of P(NDI2OD‐T2) films with different crystalline structures are closely correlated. Notably, the 10‐thiol‐enabled facile tailoring of the crystal orientation in P(NDI2OD‐T2) can be readily applied to other D–A copolymers of interest. The findings of this study highlight a robust solvent additive strategy for regulating solution aggregates and crystal orientation in D–A copolymer films, which have applications in many optoelectronic devices. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A hierarchically assembled necklace composed of amphiphilic diblock copolymer micelles is exquisitely produced by capitalizing on two concurrent self‐assembly processes at different scales (i.e., "breath figure" strategy of diblock copolymer micelles solution evaporating in humid air to yield rings at the microscopic scale in conjunction with self‐assembly of diblock copolymer micelles within individual ring at the nanometer scale). Intriguingly, hierarchical rings of diblock copolymer micelles comprising gold precursors or fluorescent dyes can also be crafted using this strategy. Upon exposure to hydrophilic block‐selective solvent, core‐corona inversion of micelles within the microscopic rings occurs. In contrast, such inversion is inhibited when the micelles are impregnated by gold precursors. This simple yet effective strategy for engineering diblock copolymer micelles may be extended to produce hierarchically assembled structures consisting of other functional block copolymers (e.g., stimuli‐responsive block copolymer) and nanocrystals (e.g., semiconducting, magnetic, ferroelectric, etc.) with unique catalytic, magnetic, ferroelectric, optical, electronic, and optoelectronic properties. [ABSTRACT FROM AUTHOR]