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The Impact of Acceptor–Acceptor Homocoupling on the Optoelectronic Properties and Photovoltaic Performance of PDTSQx ff Low Bandgap Polymers
Author(s) -
Pirotte Geert,
Kesters Jurgen,
Cardeynaels Tom,
Verstappen Pieter,
D'Haen Jan,
Lutsen Laurence,
Champagne Benoît,
Vanderzande Dirk,
Maes Wouter
Publication year - 2018
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201800086
Subject(s) - acceptor , materials science , conjugated system , quinoxaline , polymer , band gap , homo/lumo , density functional theory , polymerization , solar cell , photovoltaic system , photochemistry , optoelectronics , polymer chemistry , chemistry , molecule , computational chemistry , organic chemistry , composite material , physics , ecology , biology , condensed matter physics
Push–pull‐type conjugated polymers applied in organic electronics do not always contain a perfect alternation of donor and acceptor building blocks. Misscouplings can occur, which have a noticeable effect on the device performance. In this work, the influence of homocoupling on the optoelectronic properties and photovoltaic performance of PDTSQx ff polymers is investigated, with a specific focus on the quinoxaline acceptor moieties. A homocoupled biquinoxaline segment is intentionally inserted in specific ratios during the polymerization. These homocoupled units cause a gradually blue‐shifted absorption, while the highest occupied molecular orbital energy levels decrease only significantly upon the presence of 75–100% of homocouplings. Density functional theory calculations show that the homocoupled acceptor unit generates a twist in the polymer backbone, which leads to a decreased conjugation length and a reduced aggregation tendency. The virtually defect‐free PDTSQx ff affords a solar cell efficiency of 5.4%, which only decreases substantially upon incorporating a homocoupling degree over 50%.