Realizing Intrinsically Stretchable Semiconducting Polymer Films by Nontoxic Additives

Abstract

Stretchable polymer semiconductors are essential materials to realize soft skin-like electronics. However, most high-mobility semiconducting polymers suffer from poor stretchability and strain-dependent charge carrier mobility. Herein, we report an approach to improve the stretchability of semiconducting polymers while maintaining charge carrier mobility. The strain independent performance was accomplished by incorporating a nontoxic small molecule, namely triacetin (TA), into high-mobility conjugated polymers. We observed that TA molecules substantially increased the stretchability of the high-mobility semiconducting polymer diketopyrrolopyrrole-thienyl-vinyl-thiophene (DPP-TVT), with a crack onset strain >100%, while the neat DPP-TVT polymer only shows a low crack onset strain <25%. The organic field-effect transistor (OFET) devices fabricated using the TA blend films maintain similar charge carrier mobility compared to the neat DPP-TVT-based devices. The influences of TA additive were further characterized, which included reduced glass transition temperature of polymer backbones, decreased modulus, and breakage of the polymer chain aggregations. The TA additive functions as a plasticizer residing in between lamellae layers of semiconducting polymers, which helps to preserve the crystalline molecular packing under deformation. We demonstrated the applicability of this approach by improving the stretchability of various semiconducting polymers using TA and its analog tricaproin. Last, a stretchable OFET array was fabricated with TA blended films, and it showed a well-maintained charge carrier mobility even after 1000 stretch–release cycles at 50% strain.

Simultaneous electro-generation/polymerization of Cu nanocluster embedded conductive poly(2,2′:5′,2′′-terthiophene) films at micro and macro liquid/liquid interfaces

“…Owing to their flexibility 1 – 3 and biocompatibility 4 , conductive polymeric thin films have seen a significant rise in usage and interest. Motivated to reduce production cost, less expensive and involved preparation methods are being sought.…”

Recent progress in stretchable organic field-effect transistors: key materials, fabrication and applications

“…The molecular additives not only improve the dynamic behavior of conjugated polymers and short-range ordered aggregates, but also improve their tensile properties without affecting the electrical properties of semiconductor polymers. 77,78 Cheng et al 79 prepared polymer composites by introducing a small molecule additive (TA) to a diketopyrrole pyrrole (DPP)based polymer. The addition of TA molecules reduces the modulus of semiconductor polymers, and TA molecules act as plasticizers between polymer crystals.…”

“…Cheng et al 79 prepared polymer composites by introducing a small molecule additive (TA) to a diketopyrrole pyrrole (DPP)-based polymer. The addition of TA molecules reduces the modulus of semiconductor polymers, and TA molecules act as plasticizers between polymer crystals.…”

Tuning the Mobility of Indacenodithiophene-Based Conjugated Polymers via Coplanar Backbone Engineering

“…4,5 In conjugated polymers, charge carriers usually transport along the chain through π-conjugation as well as between chains through π−π stacking. 6,7 Optimizing molecular structures thus represents an essential approach to realizing good charge transport. 8 It is widely believed that a rigid conjugated backbone and long-range order with strong π−π interactions are beneficial for charge carrier mobility.…”

“…In recent years, conjugated polymers have received increasing research interest as promising semiconducting materials in organic electronics due to their mechanical flexibility, lightweight, and solution processability. − In organic field-effect transistors (OFETs), the mobility of conjugated polymers can be greatly improved from ∼10 –5 to >10 cm 2 /(V s) through the optimization of polymer structures and device fabrication. , In conjugated polymers, charge carriers usually transport along the chain through π-conjugation as well as between chains through π–π stacking. , Optimizing molecular structures thus represents an essential approach to realizing good charge transport . It is widely believed that a rigid conjugated backbone and long-range order with strong π–π interactions are beneficial for charge carrier mobility.…”