Increasing the Content of β Phase of Poly(9,9-dioctylfluorene) by Synergistically Controlling Solution Aggregation and Extending Film-forming Time

Liu, Ya-Di; Zhang, Qiang; Yu, Xinge; Liu, Jiangang; Han, Yanchun

doi:10.1007/s10118-019-2259-3

Cited by 36 publications

(25 citation statements)

References 63 publications

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“…Finally, these rigid-rod chains tightly pack into ordered aggregates in solution. Besides decreasing solution temperature, other methods, such as reducing solvent quality, − ultrasonic oscillation, − and shearing flow, , can also induce the disorder–order transition in solution. In addition, as concentration of conjugated polymer increases, more complex structures can form, such as the anisotropic nematic liquid crystals, interconnected networks with physically cross-links, and even the immobile gels. − More importantly, these preformed aggregates can be kept during solution deposition and thus are memorized or inherited in the solid films, − which can significantly improve the molecular ordering in the resultant conjugated polymer films.…”

Section: Optimizing Film Microstructure For Balanced Electrical and M...mentioning

confidence: 99%

Optimizing Morphology to Trade Off Charge Transport and Mechanical Properties of Stretchable Conjugated Polymer Films

et al. 2021

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Conjugated polymers are a promising candidate for large-area stretchable electronics because of their tunable electrical and mechanical properties, light weight, and low-cost solution processing. Significant research progress has been achieved in stretchable polymer electronics by synthesizing novel conjugated polymer materials and designing new device geometries. However, the inherent competition between high charge mobility and good mechanical compliance has long existed for conjugated polymer films. In this Perspective, we will provide an understanding of how to balance the electrical properties and mechanical properties from the point of view of multiple length scale microstructures of conjugated polymers. After a brief introduction of microstructure features, charge transport, and mechanical properties in thin films, we focus on how to design the percolation morphology with the aggregates, tie chains, and amorphous phase via controlling solution preaggregation and film-formation dynamics. Furthermore, the rational transfer of film morphology from small-area coating to large-area printing is discussed in terms of film uniformity and crystallization control. Finally, we summarize the challenges and opportunities in microstructure control of stretchable conjugated polymer films.

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Section: Optimizing Film Microstructure For Balanced Electrical and M...mentioning

confidence: 99%

Optimizing Morphology to Trade Off Charge Transport and Mechanical Properties of Stretchable Conjugated Polymer Films

et al. 2021

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“…For film preparation, the solution was drop-cast in a CF solvent vapor atmosphere to prolong the film-drying time, thereby promoting the film order. , A disadvantage of conventional drop cast is that the films are usually not homogeneous due to droplet sliding . Here, we modified the drop-cast process by removing the excess solution prior to solvent evaporation, and the film uniformity was significantly improved (Figure S1).…”

Section: Experimental Sectionmentioning

confidence: 99%

Role of Molecular Weight in Microstructural Transition and Its Correlation to the Mechanical and Electrical Properties of P(NDI2OD-T2) Thin Films

Zhao

Zhang

et al. 2021

Macromolecules

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Semiconducting polymers with high mobility and mechanical robust properties are strongly dependent on their molecular weight. However, the relationship between molecular weights and solution chain entanglements, film microstructures, charge carrier mobility, and mechanical properties for donor−acceptor conjugated polymers remains less understood. Herein, P(NDI2OD-T2) with a weight-average molecular weight (M w ) from 34.0 to 280 kDa was investigated as a model system. The polymer chain exhibited three regions in chloroform solutions: fewer entanglements (34.0−77.7 kDa), enhanced entanglements (170 kDa), and severe entanglements (280 kDa). This chain solution behavior resulted in three distinct film microstructures: (1) 34.0−77.7 kDa, liquid-crystalline-like morphologies with highly ordered chain arrangements and large crystallite lengths (l c ) yet relatively low tie-chain densities that increased with M w ; (2) 170 kDa, small fibril morphology with less ordered chain arrangements and a decreased l c of only 5.6 nm yet a high tie-chain density; and (3) 280 kDa, a seemingly amorphous film with vast wellconnected local aggregates embedded in an entangled network. The structural change in films significantly affected the electrical and mechanical performances. The electron mobility increased continuously with M w , correlating well with the tie-chain density. By contrast, the crack-onset strain was less than 3% at 34.0−77.7 kDa and then jumped to 36.4 ± 0.9 and 60.4 ± 2.1% for 170 and 280 kDa, showing a close correlation with the solution entanglement density, which could be inherited into films. This study contributes to structural development of rigid chains with M w and demonstrates that the microstructure containing vast well-connected local aggregates and adequate entanglements is promising toward mechanically robust semiconducting films.

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“…In contrast, in the Tol solution, high-density aggregates formed before aging. These aggregates could serve as “seed crystallite nuclei”, triggering the formation of lots of small fibrils in the film. , After aging, the aggregation in Tol remained unchanged. Thus, the film morphology was identical to that of the unaged Tol solution.…”

Section: Results and Discussionmentioning

confidence: 99%

Nucleation and Growth of P(NDI2OD-T2) Nanowires via Side Chain Ordering and Backbone Planarization

et al. 2021

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Conjugated polymer nanowires with long-range order can significantly enhance charge carrier mobility. However, nanowires of P(NDI2OD-T2) with lengths up to the micron scale have not been reported yet due to fast backbone aggregation. Herein, we proposed to prepare P(NDI2OD-T2) nanowires through slow nucleation via side chain ordering first and then backbone planarization by enhancing the side chain interaction. For this purpose, two selective solvents were used, with bromonaphthalene (BrN) dissolving the P(NDI2OD-T2) backbone and toluene (Tol) dissolving the side chain, respectively. For BrN, the initial solution contained only P(NDI2OD-T2) unimer coils with both the backbone and side chain disordered. In the subsequent aging process, P(NDI2OD-T2) side chain ordering took place first then inducing backbone planarization. The resulting extended chains stacked slowly into nuclei upon the side chain interaction. During the final film-drying process, these nuclei grew into well-defined nanowires with lengths up to tens of micrometers and a width of 20 nm. Structural analysis revealed that the polymer chains aligned parallel to the long axis of the nanowire in an edge-on orientation. In contrast, in Tol, P(NDI2OD-T2) chains aggregated immediately into too many rod-like nuclei upon strong backbone interaction, which resulted in high-density small fibrils in the film. The results obtained herein reveal the subtle role of the backbone and side chain in nucleation and demonstrate that the nucleation pathway can be readily controlled using selective solvents, thereby manipulating the final film morphology of conjugated polymers.

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Increasing the Content of β Phase of Poly(9,9-dioctylfluorene) by Synergistically Controlling Solution Aggregation and Extending Film-forming Time

Cited by 36 publications

References 63 publications

Optimizing Morphology to Trade Off Charge Transport and Mechanical Properties of Stretchable Conjugated Polymer Films

Optimizing Morphology to Trade Off Charge Transport and Mechanical Properties of Stretchable Conjugated Polymer Films

Role of Molecular Weight in Microstructural Transition and Its Correlation to the Mechanical and Electrical Properties of P(NDI2OD-T2) Thin Films

Nucleation and Growth of P(NDI2OD-T2) Nanowires via Side Chain Ordering and Backbone Planarization

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