Influences of the backbone randomness on the properties, morphology and performances of the fluorinated benzoselenadiazole–benzothiadiazole based random copolymers

Chen, Yung Tsung; Huang, Tzu Wei; Wang, Chien‐Lung; Hsu, Chain‐Shu

doi:10.1039/c5py00175g

Cited by 16 publications

(14 citation statements)

References 53 publications

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“…Though the majority of the published reports investigated the substitution of thiophene with selenophene or even tellurophene, some attempted a similar strategy in engineering the acceptors, for example, by replacing the sulfur in the benzothiadiazole unit with selenium/tellurium . The Hsu group conducted studies comparing the fluorinated benzoselenadiazole with the fluorinated benzothiadiazole . They observed a higher J sc in the former polymer based devices whereas the overall efficiency was higher for the latter.…”

Section: Molecular Engineering (Backbone Substituents and Side Chains)mentioning

confidence: 99%

Molecular Engineering of Conjugated Polymers for Solar Cells: An Updated Report

2016

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The device efficiency of polymer:fullerene bulk heterojunction solar cells has recently surpassed 11%, as a result of synergistic efforts among chemists, physicists, and engineers. Since polymers are unequivocally the "heart" of this emerging technology, their design and synthesis have consistently played the key role in the device efficiency enhancement. In this article, the first focus is a discussion on molecular engineering (e.g., backbone, side chains, and substituents), then the discussion moves on to polymer engineering (e.g., molecular weight). Examples are primarily selected from the authors contributions; yet other significant discoveries/developments are also included to put the discussion in a broader context. Given that the synthesis, morphology, and device physics are inherently related in explaining the measured device output parameters (J , V and FF), we will attempt to apply an integrated and comprehensive approach (synthesis, morphology, and device physics) to elucidate the fundamental, underlying principles that govern the device characteristics, in particular, in the context of disclosing structure-property correlations. Such correlations are crucial to the design and synthesis of next generation materials to further improve the device efficiency.

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Section: Molecular Engineering (Backbone Substituents and Side Chains)mentioning

confidence: 99%

Molecular Engineering of Conjugated Polymers for Solar Cells: An Updated Report

2016

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“…These unsubstituted-TVT-based copolymers have delivered superior OFET mobilities. Recently, several compact electron acceptors such as difluorobenzothiadiazole (FBT) and naphtho[1,2- c :5,6- c ]bis[1,2,5]thiadiazole (NT) have been utilized to make various D–A copolymers that have shown high OFET mobilities and OPV efficiencies. − It is of great interest to further combine the TVT donor with FBT or NT acceptors for developing new promising TVT-based polymers. However, it is synthetically unable to introduce aliphatic side chains to these thiadiazole-based acceptors.…”

Section: Introductionmentioning

confidence: 99%

Thiophene–Vinylene–Thiophene-Based Donor–Acceptor Copolymers with Acetylene-Inserted Branched Alkyl Side Chains To Achieve High Field-Effect Mobilities

Chiou

Hung

et al. 2018

Chem. Mater.

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2-Alkyl (1) alkyl (2) -type aliphatic side chains with a branching point position at the C 2 -position (such as 2-ethylhexyl or 2-octayldodecyl) have been widely implanted into numerous donor−acceptor conjugated copolymers for solution processable transistors or organic solar cells. However, the tertiary branching site located at the second carbon inevitably imposes steric hindrance that twists the main-chain coplanarity and attenuates interchain interactions. In this research, we developed a new two-dimensonal thiophene−vinylene−thiophene (TVT) derivative where a carbon−carbon triple bond is inserted between the thiophene unit and the 2-octyldodecyl group. This acetylene-incorporated TVT (aTVT) was copolymerized with 5,10-di(thiophen-2-yl)naphtho[1,2-c:5,6-c′]bis-([1,2,5]thiadiazole) (DTNT) and 5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTFBT) to form the polymers PaTVT-NT and PaTVT-FBT, respectively. PTVT-FBT, without the triple bond, was also prepared for comparison. The insertion of a linear triple bond moves the tertiary carbon away from the main chain to reduce the steric hindrance, thereby improving the main-chain coplanarity and facilitating the interchain interactions. The acetylene-incorporated copolymers show better thermal stability, red-shifted absorption spectra, stronger intermolecular aggregation, lower-lying electron affinity, and much higher solid-state crystallinity. Due to the linear and coplanar polymeric backbone supported by theoretical calculation, PaTVT-NT exhibits high crystallinity and adopts strong stacking with an edge-on orientation in the thin film evidenced by 2D-GIXRD, leading to a high p-type OFET mobility up to 1.27 cm 2 V −1 s −1 with an on−off ratio of 9.22 × 10 5 . This value represents the highest value among the NT-based polymers. PaTVT-FBT also achieved a high mobility of 0.78 cm 2 V −1 s −1 , which greatly outperforms the corresponding nonacetylene PTVT-FBT counterpart. Most importantly, the preparation of 2-alkyl (1) alkyl (2) −acetylenyl side chain is synthetically feasible, which can be easily applied to create new conjugated polymers for high-performance solution-processable optoelectronics.

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“…Additionally, the heteroatoms on the 5,6‐difluorobenzothiadiazole can promote various noncovalent interactions, which are beneficial to backbone planarity and charge carrier transport . As a result, the ffBT‐tetrathiophene copolymer exhibits remarkable p‐channel performance with hole mobility (μ h ) > 1 cm 2 V −1 s −1 . As the difluorobenzothiadiazole analogue, difluorobenzoxadiazole (ffBX) was recently reported by Yan and co‐workers and its incorporation into polymer semiconductors results in promising power conversion efficiency (>9%) in polymer solar cells (PSCs) .…”

Section: Introductionmentioning

confidence: 99%

Difluorobenzoxadiazole‐Based Polymer Semiconductors for High‐Performance Organic Thin‐Film Transistors with Tunable Charge Carrier Polarity

Shi

Wang

Uddin

et al. 2017

Adv Elect Materials

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A series of difluorobenzoxadiazole‐based copolymers are synthesized for applications in high‐performance organic thin‐film transistors. Four π‐spacers with distinct electrical properties, bithiophene, difluorobithiophene, 2‐thiophene‐2′‐thiazole, and bithiazole, are inserted between head‐to‐head linkage containing bithiophene to promote polymer chain packing. Among the series, polymer containing bithiophene exhibits a unipolar p‐channel performance with a substantial hole mobility of 2.92 cm2 V−1 s−1, and minor structural modification leads to polymer containing bithiazole showing a remarkable unipolar n‐channel performance with an electron mobility of 0.83 cm2 V−1 s−1. Through a simple structural modification, such a drastic charge carrier polarity change without sacrificing mobility is elusive in organic thin‐film transistor field. Polymer containing hybrid 2‐thiophene‐2′‐thiazole spacer exhibits ambipolarity with encouraging hole/electron mobility of 0.27/0.35 cm2 V−1 s−1, and polymer containing difluorobithiophene shows an average hole mobility of 0.53 cm2 V−1 s−1. Among the results, p‐channel transistors exhibit encouraging device stability. The results demonstrate that difluorobenzoxadiazole is a versatile building block for enabling high‐mobility semiconductors with variable charge carrier polarity. X‐ray diffraction reveals that all difluorobenzoxadiazole‐based polymers have substantial film crystallinity with close π‐stacking and varied polymer chain orientation. The structure–property–device performance correlations from this study offer useful insights for materials innovation in organic thin‐film transistors.

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Influences of the backbone randomness on the properties, morphology and performances of the fluorinated benzoselenadiazole–benzothiadiazole based random copolymers

Cited by 16 publications

References 53 publications

Molecular Engineering of Conjugated Polymers for Solar Cells: An Updated Report

Molecular Engineering of Conjugated Polymers for Solar Cells: An Updated Report

Thiophene–Vinylene–Thiophene-Based Donor–Acceptor Copolymers with Acetylene-Inserted Branched Alkyl Side Chains To Achieve High Field-Effect Mobilities

Difluorobenzoxadiazole‐Based Polymer Semiconductors for High‐Performance Organic Thin‐Film Transistors with Tunable Charge Carrier Polarity

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