Balancing the trade-off between the mechanical and electrical properties of conjugated polymer blend films for organic field-effect transistors

Abstract

Intrinsically stretchable organic field-effect transistors (OFETs) with all stretchable device components present a huge potential for future “skin-like” stretchable electronics. However, there generally exists a trade-off between mobility and stretchability in a single semiconductor material. In this work, a strategy of blending poly(3-hexylthiophene) (P3HT) with poly[[2,5-bis(2-octyldodecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-alt-[[2,2-(2,5-thiophene)bis-thieno[3,2-b] thiophen]-5,5′-diyl]] (DPPT-TT) is proposed to well balance the trade-off between the mechanical and electrical performance of the OFET device. The blend ratio of the two polymer solution has been proved to exhibit significant effects to achieve a “win–win” situation. The mobility of the optimized blend film is 0.33 cm² V⁻¹ s⁻¹, enhanced by one order of magnitude compared to the neat P3HT film. Almost no cracks appeared in the blend film under a 100% strain, presenting a five-fold improvement compared to the neat DPPT-TT film. Considering the optical properties, thin-film morphology and surface energy, we concluded that such a balance between mobility and stretchability benefits from the interpenetrating network structure of the blend films. Moreover, the stretched blend film maintained a relatively stable mobility until the strain increased to 75%. Our findings can offer a promising approach to balance the trade-off between the mechanical and electrical properties for the future fabrication of high-performance stretchable electronics.