2014 Volume 27 Issue 3 Pages 321-326
Two newly developed narrow bandgap polymers containing benzobis(thiadiazole) (BBT) have been synthesized using the Stille coupling reaction. The polymers showed absorption in the near infrared region due to strong charge-transfer interactions in the donor-acceptor (D-A) units, suggesting a rigid planarized structure. Although both the HOMO-LUMO levels of the polymers lie close to the work function of gold electrodes, a BBT-quaterthiophene polymer showed only p-type semiconducting behavior. In addition, the dominant charge-carrier type is holes even in BBT-thiazole-thiophene polymers, which consists mainly of acceptor units, and indicates that the thiophene ring in these polymers has a strong influence on the charge transport properties.