Photovoltaic Small Molecules of TPA(FxBT-T-Cz)3: Tuning Open-Circuit Voltage over 1.0 V for Their Organic Solar Cells by Increasing Fluorine Substitution.
To simultaneously improve both open-circuit voltage (Voc) and short-circuit current density (Jsc) for organic solar cells, a novel D(A-π-Ar)3type of photovoltaic small molecules of TPA(FxBT-T-3Cz)3was designed and synthesized, which contain central triphenylamine (TPA), terminal carbazole (Cz), armed fluorine-substituted benzothiadiazole (FxBT, where x = 1 or 2), and bridged thiophene (T) units. A narrowed ultraviolet-visible absorption and a decreasing highest occupied molecular orbital energy level were observed from TPA(F1BT-T-3Cz)3to TPA(F2BT-T-3Cz)3with increasing fluorine substitution. However, the TPA(F2BT-T-3Cz)3/PC71BM-based solar devices showed a rising Vocof 1.01 V and an enhanced Jscof 10.84 mA cm-2as well as a comparable power conversion efficiency of 4.81% in comparison to the TPA(F1BT-T-3Cz)3/PC71BM-based devices. Furthermore, in comparison to the parent TPA(BT-T-3Cz)3molecule without fluorine substitution, the fluorine-substituted TPA(FxBT-T-3Cz)3molecules exhibited significantly incremental Vocand Jscvalues in their bulk heterojunction organic solar cells, owing to fluorine incorporation in the electron-deficient benzothiadiazole unit.
College of Chemistry, Xiangtan University , Xiangtan, Hunan 411105, People's Republic of China.
Qiong
Q
Wang
College of Chemistry, Xiangtan University , Xiangtan, Hunan 411105, People's Republic of China.|Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao, Shandong 26610, People's Republic of China.
Linrui
L
Duan
College of Chemistry, Xiangtan University , Xiangtan, Hunan 411105, People's Republic of China.
Qiang
Q
Tao
College of Chemistry, Xiangtan University , Xiangtan, Hunan 411105, People's Republic of China.
Wenhong
W
Peng
College of Chemistry, Xiangtan University , Xiangtan, Hunan 411105, People's Republic of China.
Jianhua
J
Chen
College of Chemistry, Xiangtan University , Xiangtan, Hunan 411105, People's Republic of China.
Hua
H
Tan
School of Materials Science and Engineering, Changzhou University , Changzhou, Jiangsu 213164, People's Republic of China.
Renqiang
R
Yang
School of Materials Science and Engineering, Changzhou University , Changzhou, Jiangsu 213164, People's Republic of China.|Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao, Shandong 26610, People's Republic of China.
Weiguo
W
Zhu
fluorine-substituted benzothiadiazole; organic solar cells; photovoltaics; star-type small molecules; triphenylamine