A New Dithienopyridine-Based Polymer for an Organic Electronics

A new dithienopyridine-based copolymer (PDT-TBT) was designed and synthesized. The copolymer showed good solubility in chloroform, chlorobenzene, and dichlorobenzene. The thermogravimetric analysis curve showed that the copolymer had good thermal stability with weight loss of less than 5% at 341 °C. The UV absorption maximum of the polymer appeared at 550 nm in solution and 600 nm in the film. The HOMO and LUMO of the copolymer were -5.50 eV and -3.63 eV, respectively. The copolymer exhibited the best performance when the PC₆₁BM ratio was 1:2 (w/w %), with a J _SC of 3.56 mA/cm², a V _OC of 0.45 V, an FF of 0.27%, and a PCE of 0.43%. A thin film transistor with PDT-TBT as the active layer showed mobility of 5.02×10^-3 cm²/Vs, an on/off ratio of 1.19×10⁵ and a threshold voltage of -22.75 V.