Tuning of the Stretchability and Charge Transport of Bis‐Diketopyrrolopyrrole and Carbazole‐Based Thermoplastic Soft Semiconductors by Modulating Soft Segment Contents

Abstract

Polymer semiconductors are promising materials for stretchable, wearable, and implantable devices due to their intrinsic flexibility, facile functionalization, and solution processability at low temperatures. However, the crystalline domain of the conjugated structure for high charge carrier mobility in semiconducting polymers exhibits lower stretchability than that of the semi‐crystalline or amorphous domains. Herein, a set of thermoplastic soft semiconductors is synthesized with different ratios of diketopyrrolopyrrole–carbazole–diketopyrrolopyrrole (DPP‐Cz‐DPP)‐based hard segments and thiophene‐based aliphatic soft segments, having the similar structure of thermoplastic elastomers. The polymers exhibit decreased glassy temperatures with the increased content of the soft segments. The polymers show high crystallinity after copolymerization with a large‐sized DPP‐Cz‐DPP core and non‐conjugated segments due to an aggregation property of the conjugated core, still possessing a semi‐crystalline domain after annealing. The polymer films exhibit stretchability under strains of up to 60%. Organic field‐effect transistors fabricated using stretchable polymers show a mobility range of 0.125–0.005 cm2 V−1 s−1 with different proportions of the soft segment. The stretchability is improved significantly and the mobilities are decreased less when the content of the soft segment is increased. Therefore, this study presents a design principle for the development of a high‐performance stretchable semiconducting polymer.

Dielectric Design of High Dielectric Constant Poly(Urea‐Urethane) Elastomer for Low‐Voltage High‐Mobility Intrinsically Stretchable All‐Solution‐Processed Organic Transistors

“…For polymer crosslinking agents NH 2 -PDMS-NH 2 and NH 2 -PEG-NH 2 based elastomers, as shown in Figure 6b,c, their soft segments can effectively increase the stretchability, [58] leading to good stretching up to 100% and the high breaking elongation of over 100%. However, with the increased molecular chain length in the polymer crosslinking agents, there are fewer urea groups within the same molecular length, resulting in the low dielectric constant and hence a high operational voltage.…”

Effect of Fluorination Position on the Crystalline Structure and Stretchability of Intrinsically Stretchable Polymer Semiconductors

“…Intrinsically stretchable polymer semiconductors (ISPSs) have recently been intensively developed to realize high-performance stretchable electronics such as field-effect transistors (FETs), solar cells, and photodetectors as they promise high stretchability without complicated patterning or additional chemical agents. − To ensure the reliable high performance of ISPS-based stretchable electronic devices, ISPSs should have excellent electrical and mechanical properties. To achieve this goal, various strategies have been attempted to control the chemical structure, crystalline structure, and/or grain size of ISPSs, with the aim of improving their charge-carrier mobility (μ) and thin-film stretchability. − However, the structure–property relationship of ISPSs has not yet been clarified, as multiple factors influence the nanomorphology and mechanical properties of polymer thin films; therefore, designing optimal molecular structures for ISPSs with high charge-carrier mobility and stretchability remains challenging.…”