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Design and synthesis of thieno[3,4‐ c ]pyrrole‐4,6‐dione based conjugated copolymers for organic solar cells
Author(s) -
Kotturappa Chandrashekara G,
Gopikrishna Murali M,
Rao Arun D,
Ramamurthy Praveen C
Publication year - 2017
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.5377
Subject(s) - thiophene , materials science , conjugated system , pyrrole , homo/lumo , copolymer , nuclear chemistry , chemistry , organic chemistry , polymer , molecule , composite material
A new series of conjugated copolymers ( PBDT‐TPD , PBDT ‐Th‐ TPD , PBDT‐TT‐TPD ) containing donor–acceptor (D − A) structure electron‐rich benzo[1,2‐ b :4,5‐ b ′]dithiophene ( BDT ) units with branched alkyl thiophene side chains and electron‐deficient 5‐(2‐octyl)‐4 H ‐thieno[3,4‐ c ]pyrrole‐4,6(5 H )‐dione (TPD) units was designed and synthesized. To tune the optical and electrochemical properties of the copolymers, the conjugation length of the copolymers was extended by introducing π‐conjugated spacers such as thiophene and thieno[3,2‐ b ]thiophene units. It was observed that PBDT‐TPD showed broader absorption spectra in the longer wavelength region and the absorption maximum was red‐shifted compared to that of PBDT‐Th‐TPD, PBDT‐TT‐TPD. Stokes shifts were calculated to be 52 nm for PBDT‐TPD, 153 nm for PBDT‐Th‐TPD and 146 nm for PBDT‐TT‐TPD. Further, PBDT‐TPD exhibited a deeper highest occupied molecular orbital energy level of −5.53 eV as calculated by cyclic voltammetry. Bulk heterojunction solar cells fabricated using PBDT‐TPD as donor material exhibited a power conversion efficiency of 1.92%. © 2017 Society of Chemical Industry