Synthesis and Characterization of Two-Dimensional Conjugated Polymers Incorporating Electron-Deficient Moieties for Application in Organic Photovoltaics

Chuen-Yo Hsiow; Han-Ying Wang; Yu-Hsiang Lin; Rathinam Raja; Syang-Peng Rwei; Wen-Yen Chiu; Chi-An Dai; Leeyih Wang

doi:10.3390/polym8110382

Synthesis and Characterization of Two-Dimensional Conjugated Polymers Incorporating Electron-Deficient Moieties for Application in Organic Photovoltaics

Polymers (Basel). 2016 Oct 27;8(11):382. doi: 10.3390/polym8110382.

Authors

Chuen-Yo Hsiow^{1

2}, Han-Ying Wang³, Yu-Hsiang Lin⁴, Rathinam Raja⁵, Syang-Peng Rwei⁶, Wen-Yen Chiu⁷, Chi-An Dai⁸, Leeyih Wang⁹

Affiliations

¹ Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan. chuenyo@caltech.edu.
² Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, CA 91125, USA. chuenyo@caltech.edu.
³ Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 10608, Taiwan. hanying1989@gmail.com.
⁴ Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 10608, Taiwan. sean76326@hotmail.com.
⁵ Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan. rajaorgchem80@gmail.com.
⁶ Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 10608, Taiwan. f10714@ntut.edu.tw.
⁷ Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan. ycchiu@ntu.edu.tw.
⁸ Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan. polymer@ntu.edu.tw.
⁹ Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan. leewang@ntu.edu.tw.

Abstract

A series of novel p-type conjugated copolymers, PTTVBDT, PTTVBDT-TPD, and PTTVBDT-DPP, cooperating benzo[1,2-b:4,5-b']dithiophene (BDT) and terthiophene-vinylene (TTV) units with/without thieno[3,4-c]pyrrole-4,6-dione (TPD) or pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) via Stille polymerization were synthesized and characterized. Copolymer PTTVBDT shows a low-lying HOMO energy level and ordered molecular-packing behavior. Furthermore, two terpolymers, PTTVBDT-TPD and PTTVBDT-DPP, display stronger absorption ability, alower-lying HOMO energy level, and preferred molecular orientation, due to the replacement TTV-monomer units with electron-deficient groups. Furthermore, bulk-heterojunction organic solar cells were fabricated using blends of the PTTVBDT-TPD, and PC₆₁BM gave the best power conversion efficiency of 5.01% under the illumination of AM 1.5G, 100 mW·cm^-2; the short circuit current (J_sc) was 11.65 mA·cm^-2 which displayed a 43.8% improvement in comparison with the PTTVBDT/PC₆₁BM device. These results demonstrate a valid strategy combining the two-dimensional molecular structure with random copolymerization strikes promising conjugated polymers to achieve highly efficient organic photovoltaics.

Keywords: benzo[1,2-b:4,5-b′]dithiophene; conjugated side chain.; polymer solar cell; pyrrolo[3,4-c]pyrrole-1,4-dione; thieno[3,4-c]pyrrole-4,6-dione; two-dimensional conjugated polymer.