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Donor-acceptor (D-A) conjugated polymers comprising electron-deficient aromatic dicarboximide units represent an important type of organic semiconductors, especially for electron transporting properties. Pyrene-1,5,6,10-tetracarboxyl diimide (PyDI), a new PAH dicarboximide molecule recently reported by us, provides a fine balance between the electron-stabilizing ability and π-stacking tendency, as compared to the naphthalenediimide (NDI) and perylenediimide (PDI) analogues. In this study, using thienylene-vinylene-thienylene (TVT) and biselenophene (BS) as the electron donating comonomer, along with PyDI as the acceptor moiety, we develop two new D-A type conjugated polymers, which exhibit impressive electron-transporting performance. Specifically, in the solution-processed OFET devices, electron mobility of 0.18 and 0.20 cm2·V−1·s−1 are achieved with these polymers, respectively. Such findings further prove the optimal potential of PyDI for application as an electron-acceptor building block in the development of polymeric n-type semiconductors among all various high-performance functional D-A polymers. [ABSTRACT FROM AUTHOR]

Electron-rich thiophene-flanked thiazoloisoindigo (Th-TzII) has been reported as a building block for ambipolar polymeric field-effect transistors however with preferable hole transport. Here, we report that by using an electron deficient thiazole as the flanked moiety, the corresponding thiazoloisoindigo (Tz-TzII) can still be synthesized, although in a more sinuous way. Theoretical calculation and experimental results demonstrate that Tz-TzII is more electron-deficient than Th-TzII, and the corresponding polymer P(TzII-Tz-T-Tz) exhibits high and balanced hole/electron mobility of 0.70/0.64 cm2·V−1·s−1. [ABSTRACT FROM AUTHOR]

A series of copolymers of thiazoloisoindigo (TzII) with different chalcogenophene trimers were synthesized to systematically investigate the chalcogen effect on their charge transport properties. When only the middle thiophene ring of terthiphene (T-T-T) is replaced by heavier chalcogenophenes, a preference (expressed by the ratio of μe/μh) towards electron transport was observed descending from T-T-T to T-Se-T then to T-Te-T (Se and Te stand for selenophene and tellurophene, respectively). On the other hand, with the increased number of heavier chalcogenophenes, a preference toward hole transport was observed descending from Se-T-Se to Se-Se-Se then to Se-Te-Se. This phenomenon is well-explained by the balance between the aromatic resonance energy of the chalcogenophenes and the electronegativity of the chalcogens. Specifically, P(TzII-T-Se-T) displayed relatively balanced ambipolar property (μhmax and μemax of 3.77 and 1.59 cm2·V−1·s−1 with a μe/μh of 0.42), while P(Tzll-Se-Te-Se) exhibited the best preference to hole transfer with a μe/μh of 0.09. P(Tzll-T-Te-T) exhibited the best preference to electron transfer with a μe/μh, of 16 and the μemax of 0.64 cm2·V−1·s−1 which is the highest electron mobility among the known conjugated polymers containing tellurophenes. [ABSTRACT FROM AUTHOR]

Controlling the solution‐state aggregation of conjugated polymers for producing specific microstructures remains challenging. Herein, a practical approach is developed to finely tune the solid‐state microstructures through temperature‐controlled solution‐state aggregation and polymer crystallization. High temperature generates significant conformation fluctuation of conjugated backbones in solution, which facilitates the polymer crystallization from solvated aggregates to orderly packed structures. The polymer films deposited at high temperatures exhibit less structural disorders and higher electron mobilities (up to two orders of magnitude) in field‐effect transistors, compared to those deposited at low temperatures. This work provides an effective strategy to tune the solution‐state aggregation to reveal the relationship between solution‐state aggregation and solid‐state microstructures of conjugated polymers. [ABSTRACT FROM AUTHOR]

The joint of the donor and acceptor moieties allows a facile and effective strategy to develop novel organic conjugated materials. However, few pieces of work report the understanding of the donor–acceptor interactions at the molecular level. Herein, we developed three small molecules containing one acceptor motif with different amounts of the donor unit. By combining theoretical calculations and energy level characterization, the lowest unoccupied molecular orbital (LUMO) levels of the three molecules were proven to be almost identical. The molecular packing modes were evaluated from crystal structure prediction. Owing to the donor–acceptor interactions, the packing mode can be tuned from a 1D slipped stacking to a 2D brick layer. The 2D molecular packing and charge transport channel endowed the materials a higher electron mobility of 3.29 cm2 V−1 s−1 in the single‐crystal field‐effect transistors after such modulation. [ABSTRACT FROM AUTHOR]

Recently, polymer field-effect transistors have gone through rapid development. Nevertheless, charge transport mechanism and structure-property relationship are less understood. Here we use strong electron-deficient benzodifurandione-based poly( p-phenylene vinylene) ( BDPPV) as polymer backbone and develop six BDPPV-based polymers ( BDPPV-C1 to C6) with various side-chain branching positions to systematically study the side-chain effect on device performance. All the polymers exhibited ambient-stable n-type transporting behaviors with the highest electron mobility of up to 1.40 cm2 V−1 s−1. The film morphologies and microstructures of all the six polymers were systematically investigated. Our results demonstrate that the interchain π-π stacking distance decreases as moving the branching position away from polymer backbones, and an unprecedentedly close π-π stacking distance down to 3.38 Å is obtained for BDPPV-C4 to C6. Nonetheless, closer π-π stacking distance does not always correlate with higher electron mobility. Polymer crystallinity, thin film disorder, and polymer packing conformation, which all influenced by side-chain branching position, are proved to show significant influence on device performance. Our study not only reveals that π-π stacking distance is not the decisive factor on carrier mobility in conjugated polymers but also demonstrates that side-chain branching position engineering is a powerful strategy to modulate and balance these factors in conjugated polymers. [ABSTRACT FROM AUTHOR]

Six fluoranthene-fused imide derivatives were employed as acceptors in solution processed inverted BHJ solar cells with P3HT as the donor. The PCEs of all devices vary from 2.14% to 2.89%. All acceptors are in their amorphous state with low electron mobility, but achieving high PCEs. [ABSTRACT FROM AUTHOR]