Tuning Conjugated Polymer Chain Packing for Stretchable Semiconductors

Abstract

In order to apply polymer semiconductors to stretchable electronics, they need to be easily deformed under strain without being damaged. A small number of conjugated polymers, typically with semicrystalline packing structures, have been reported to exhibit mechanical stretchability. Herein, a method is reported to modify polymer semiconductor packing‐structure using a molecular additive, dioctyl phthalate (DOP), which is found to act as a molecular spacer, to be inserted between the amorphous chain networks and disrupt the crystalline packing. As a result, large‐crystal growth is suppressed while short‐range aggregations of conjugated polymers are promoted, which leads to an improved mechanical stretchability without affecting charge‐carrier transport. Due to the reduced conjugated polymer intermolecular interactions, strain‐induced chain alignment and crystallization are observed. By adding DOP to a well‐known conjugated polymer, poly[2,5‐bis(4‐decyltetradecyl)pyrrolo[3,4‐c]pyrrole‐1,4‐(2H,5H)‐dione‐(E)‐1,2‐di(2,2′‐bithiophen‐5‐yl)ethene] (DPPTVT), stretchable transistors are obtained with anisotropic charge‐carrier mobilities under strain, and stable current output under strain up to 100%.

Molecular Design of Stretchable Polymer Semiconductors: Current Progress and Future Directions

“…In addition to modifying chemical structures, introducing a secondary component is a promising direction. Related approaches include blending with an insulating elastomer, − crosslinking, , and plasticizing with small molecules − (Figure A). However, simple mixing without promoting the suitable morphology may result in only improved mechanical stretchability with a significant reduction of charge carrier mobilities because the insulating components can hinder charge transport between semiconducting domains.…”

“…(C) Chemical structures and schematics of the conjugated polymer-chain packing morphologies before and after DOP treatment. Reprinted with permission from ref . Copyright 2021 Wiley.…”

“…Small-molecule additives can be used to modulate the mechanical properties of conjugated polymers, including cycloparaphenylenes (CPPs), branched polyethylene, dioctyl phthalate (DOP), and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) . We have recently used CPPs to tune the dynamic behaviors of diketopyrrolopyrrole-based (DPP-based) semiconducting polymers (Figure B).…”

Natural Material Inspired Organic Thin-Film Transistors for Biosensing: Properties and Applications

“…Copyright 2021 Springer Nature. Molecular spacer, reprinted from ref . Copyright 2021 John Wiley and Sons.…”

Triphenyleno[1,2-c:7,8-c′]bis([1,2,5]thiadiazole) as a V-Shaped Electron-Deficient Unit to Construct Wide-Bandgap Amorphous Polymers for Efficient Organic Solar Cells

“…Semiconducting polymers have attracted much attention because of their various applications in the field of organic optoelectronics, such as organic light-emitting diodes, , organic field effect transistors, − and organic solar cells (OSCs). − One of the appealing advantages of semiconducting polymers is their tunable properties, such as the optical absorption, molecular energy levels, and carrier mobility in thin films. − The most efficient strategy for tailoring these properties is integrating alternating donor (D) and acceptor (A) units along the backbone to form D–A copolymers . In D–A copolymers, the electronic properties and morphologies in thin films, and thereby their light-harvesting and charge transport properties, are highly dependent on the chemical and electronic structures of the D and A units as well as the way that the units are combined. − Therefore, designing D and A building blocks is critical for developing high-performance polymers for optoelectronic applications.…”