Poly(thienylene-benzothiadiazole-thienylene-vinylene): A narrow bandgap polymer with broad absorption from visible to infrared region

Poly(thienylene-benzothiadiazole-thienylene-vinylene) (PTBTV) has been synthesized by Pd-catalyzed Stille-coupling method. The polymer shows broad absorption from visible to infrared region. The maximum absorption of PTBTV in solution and film state is at 600 nm and 614 nm, respectively. The absorption edge of PTBTV film is at 813 nm, indicating a narrow bandgap of 1.50 eV. The HOMO and LUMO energy levels of PTBTV are −4.99 eV and −3.49 eV, respectively. Polymer solar cell based on the blend of PTBTV as donor and [70] PCBM as acceptor was fabricated, the power conversion efficiency of the device is 0.51% under the illumination of AM1.5, 100 mW/cm2.