Simultaneous Enhancement of Stretchability, Strength, and Mobility in Ultrahigh-Molecular-Weight Poly(indacenodithiophene-co-benzothiadiazole)

Abstract

To simultaneously obtain outstanding stretchability, strength, and charge mobility of conjugated polymers (CPs) has remained a challenge for the field of stretchable electronics to date. Herein, we propose a strategy of increasing the molecular weight of a near-amorphous CP poly(indacenodithiophene-co-benzothiadiazole) (IDT-BT) to an ultrahigh level to overcome the trade-off. Detailed molecular weight-dependent study confirms that increasing the molecular weight can simultaneously enhance the mechanical and charge transport properties of IDT-BT, owing to the higher extent of chain entanglement and a larger range of charge transport along the backbone. Ultrahigh-molecular-weight (1049.6 kg mol −1 , weight average) IDT-BT exhibited the highest mobility of 2.63 cm 2 V −1 s −1 , modulus of 1126.7 MPa, elastic recovery >80%, crack onset strain >100%, fracture strain ≥20%, and a crack-free morphology after 100 cycles of strain. To the best of our knowledge, the ultrahigh-M w IDT-BT outperforms previously reported stretchable CPs by exhibiting enhanced elasticity, strength, and charge mobility at the same time.

Near-Amorphous Conjugated Polymers: An Emerging Class of Semiconductors for Flexible Electronics

“…As a result, the field effect mobility increased from 0.56 to 1.95 cm 2 V –1 s –1 in the IDT-BT film. By using the highly reactive catalyst Buchwald-G3-XPhos to improve the reaction speed and then avoid the deborization of electron deficient borate esters with time, Geng et al synthesized IDT-BT with a high M w (1049.6 kg mol –1 ) . The resulting IDT-BT exhibited a mobility of 2.63 cm 2 V –1 s –1 (Figure a).…”

“…By using the highly reactive catalyst Buchwald-G3-XPhos to improve the reaction speed and then avoid the deborization of electron deficient borate esters with time, Geng et al synthesized IDT-BT with a high M w (1049.6 kg mol −1 ). 54 The resulting IDT-BT exhibited a mobility of 2.63 cm 2 V −1 s −1 (Figure 4a). Notably, the change of molecular weight will lead to a change of the mechanical properties of near-amorphous polymers, which will be discussed in the next section.…”

Extending the p-Doping of Polymers to an Air Stable Lewis Acid–Base Adduct by Increasing the Acidity of the Dopant

“…IDT-BT was synthesized following the reported procedure . The number-average molecular weight and polydispersity index were 12.5 kDa and 2.35, respectively.…”

“…The miscibility of OSC and dopant also limits the doping efficiency and accuracy, since severe aggregation of dopant molecules would happen given poor compatibility of the two. The recently reported conjugated polymer poly­(indacenodithiophene- co -benzothiadiazole) (IDT-BT) has attracted extensive attention due to its amorphism and high mobility, − and it is expected to be a suitable OSC to study the doping with Lewis acids by affording basic N atoms for adduct formation.…”

Side-Chain Engineering of Conjugated Polymers for High-Performance Organic Field-Effect Transistors

“…Despite the gratifying achievement, some critical problems should be considered. The structure of conjugated polymers is multiple, and molecular conformational changes from the monomer to the whole network make the intra- and intermolecular complicated. − Therefore, the investigation of polymer self-assembly behavior is often difficult. By employing side-chain engineering, chemical and physical properties of a conjugated polymer, including the polymer main-chain structure, molecular weight, and its distribution, should be considered together.…”