Synthesis and Characterization of Diketopyrrolopyrrole-Based Conjugated Polymers with Bithiophene and Biselenophene for Organic Thin Film Transistors

Abstract

In this study, two new thieno[3,2-b] thiophene-diketopyrrolopyrrole (DPP)-based polymers, poly{2,5-bis(2-dodecylhexadecyl)-3,6-bis(thieno[3,2-b] thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-2,2'-bithiophene} (PTTDPP-BT) and {2,5-bis(2-dodecylhexadecyl)-3,6-bis(thieno[3,2-b] thiophen-2-yl) pyrrolo[3,4-c] pyrrole-1,4(2H, 5H)-dione-alt-2,2'-selenophene} (PTTDPP-BSe), which contained bithiophene (BT) and biselenophene (BSe) units, respectively, were designed and synthesized. The introduction of BT and BSe units affected the optical, electrochemical, morphological, and charge transport properties of the polymers. Experimental results revealed that the frontier molecular orbital energy levels of PTTDPP-BT were slightly higher because of the relatively strong electron donating ability of the sulfur atom and the polymer also exhibited good solubility. The maximum mobility in the case of PTTDPP-BT at 250 degrees C was 0.068 cm(2) V-1 s(-1) and that of PTTDPP-BSe was 0.029 cm(2) V-1 s(-1) (at 200 degrees C).