Acceptor manipulation of bisalkylthiothienyl benzo[1,2-b:4,5-b']dithiophene core-structured oligomers for efficient organic photovoltaics

• Published in: Dyes and pigments 2017-05, Vol.140, p.512-519
• Main Authors: Yin, Xinxing, An, Qiaoshi, Yu, Jiangsheng, Xu, Zhongsheng, Deng, Ping, Geng, Yongliang, Zhou, Baojing, Zhang, Fujun, Tang, Weihua
• Format: Article
• Language: English
• Subjects: Benzo[1,2-b:4,5-b']dithiophene; Bisalkylthio; Molecular donor; Organic solar cells; Sidechain engineering
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2016.10.040

Three novel small molecules named DR3TDST, DRCN3TDST and DB3TDST containing bisalkylthiothienyl side-chain on benzo[1,2-b:4,5-b']dithiophene (BDT) core with different electron-deficient ending-groups are designed and synthesized. All three molecules have deep HOMO energy level from −5.40 eV to −5.44 eV, indicating introduction of bisalkylthio group to BDT is an effective method to modulate the molecular energy levels. Different ending-groups exhibit small but measurable effects on absorption, energy level, charge transport, morphology, and photovoltaic properties of small molecules. Bulk heterojunction solar cells fabricated with DRCN3TDST and PC71BM deliverer the highest power conversion efficiency (PCE) of 5.17% after annealing and solvent vapor annealing. Benzo[1,2-b:4,5-b']dithiophene (BDT) core-structured small molecules with bisalkylthio side-group lowered HOMO levels showed the highest power conversion efficiency (PCE) of 5.17% in OSCs. [Display omitted] •The synthesis of bisalkylthiobenzo[1,2-b:4,5-b']dithiophene based oligomers.•The electrochemical characterization and molecular simulation of oligomers.•The effect of ending acceptor on bisalkylthio BDT oligomer properties.•The highest PCE of 5.17% for oligomer based OPVs.