D-π-A-π-A Strategy to Design Benzothiadiazole-carbazole-based Conjugated Polymer with High Solar Cell Voltage and Enhanced Photocurrent

Macromolecular rapid communications(2015), 36(24), 2156-61.

Zhou Manxi, Wang Min, Zhu Lei, Li Qifang, Yang Zhenqing, Cao Dapeng, Jiang Chao

Abstract: The theoretical calculations are used to find that D-π-A-π-A style conjugated polymer PC-TBTBT is more efficient for solar cells application than the D-π-A ****og PC-TBT because the D-π-A-π-A structure has a narrower band gap and higher molar absorption coefficient and redshift spectrum.  Motivated by the theoretical prediction, 5,6-bis(octyloxy)-2,1,3-benzothiadiazole and 2,7-carbazole are adopted to synthesize the D-π-A-π-A style PC-TBTBT (M(w) = 31.1 kDa) and D-π-A ****og PC-TBT (M(w) = 87.5 kDa) by Suzuki coupling reaction. Experimental results confirm that D-π-A-π-A PC-TBTBT-based solar cell shows a power conversion efficiency (PCE) of 4.74% with high V(OC) of 0.99 V and enhanced J(SC) of 9.70 mA cm(-2). The PCE and J(SC) achieve improvements of 17% and 26%, respectively, compared to the D-π-A PC-TBT-based solar cell.