Tuning molecular energy levels and band gap of two-dimensional benzo[1,2-b:4,5-b '] dithiophene and quinoxaline bearing polymers

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Yasa M., Goker S., Udum Y., Toppare L.

JOURNAL OF ELECTROANALYTICAL CHEMISTRY, vol.847, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 847
  • Publication Date: 2019
  • Doi Number: 10.1016/j.jelechem.2019.113260
  • Journal Name: JOURNAL OF ELECTROANALYTICAL CHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: Quinoxaline, Furan, Selenophene, Benzodithiophene, Stille polycondensation, Organic solar cells (OSCs), CONJUGATED POLYMERS, SOLAR-CELLS, NAPHTHALENE DIIMIDE, FURAN, PERFORMANCE, BENZOTHIADIAZOLE, BENZODITHIOPHENE, COPOLYMERS, EFFICIENCY, ACCEPTOR
  • Middle East Technical University Affiliated: Yes

Abstract

Two novel donor-acceptor (D-A)-type two-dimensional (2-D) polymers of PBDTSeQ (P1) and PBDTFQ (P2) were synthesized and characterized where 4,8-bis[5-(2-ethylhexyl) thiophen-2-yl] benzo[1,2-b:4,5-b'] dithiophene (BDT) was used as the donor unit. 2,3-Bis(3,4-bis(octyloxy)phenyI)-5,8-dibromoquinoxaline was used as the acceptor moiety and selenophene and furan were utilized as n bridges. Optoelectronic properties of the polymers were examined by electrochemical and spectroelectrochemical characterizations. In cyclic voltammetry (CV) studies, both polymers were found to be ambipolar. In anodic region, oxidation potentials were observed as 1.45 V and 1.15 V for P1 and P2 respectively, while reduction potentials were 0.65 V and 0.92 V. In cathodic region, redox potentials were found to be -1.36 V/-1.32 V and -2.0 V/-1.51 V for P1 and -1.45 V/-1.05 V and -2.15 V/-1.45 V for P2. Both polymers showed good solubility in common solvents. The synthesized polymers were used as photoactive layers in solar cell devices. P1-based device (ITO/PEDOT:PSS/P1:PC71BM (1:3, w/w)/LiF/Al) provided the best performance with a PCE of 4.04%, a V-OC of 0.67 V, a Jsc of 13.94 mA/cm(2), and a FF of 43.3%.