Synthesis and characterization of thieno-isoindigo derivative-based near-infrared conjugated polymer for ambipolar field-effect transistors and photothermal conversion

Abstract

A new thieno-isoindigo derivative, (3E,7E)-3,7-bis(4-(2-decyltetradecyl)-4H-thieno[3,2-b]pyrrole-5,6-dione)-5,7-dihydropyrrolo[2,3-f]indole-2,6(1H,3H)-dione (BTPDI), was designed and synthesized. A donor−acceptor conjugated polymer (PBTPDI-TT) was also synthesized with this new unit as the acceptor and thieno[3,2-b]thiophene as the donor. The microstructure, photophysical, electrochemical, field-effect properties and photothermal performances were investigated. The polymer showed a broad absorption spectrum that spanned across the near-infrared (NIR) region (780–1300 nm), with a very low bandgap (∼0.95 eV), deep lowest unoccupied molecular orbital, and suitable highest occupied molecular orbital levels. As a result, the polymer-based organic field-effect transistors showed highly balanced hole and electron transport characteristics with a hole mobility of 0.027 cm2 V−1s−1 and an electron mobility of 0.022 cm2 V−1s−1. The polymer nanoparticles showed good reusability under NIR (980 nm) irradiation and could also effectively convert NIR light to heat at an excellent efficiency of 20.3%.