Syntheses of biaxially extended octithiophene-based conjugated copolymers for high-open-circuit-voltage photovoltaic-cell applications
Journal
Macromolecular Chemistry and Physics
Journal Volume
215
Journal Issue
7
Pages
638-647
Date Issued
2014
Author(s)
Abstract
Novel biaxially extended octithiophene (8T)-based conjugated polymers are successfully synthesized using Stille coupling reactions of the branched octithiophene moiety with selenophene (P8TSe), thiophene (P8TT), and thieno[3,2-b]thiophene (P8TTT). The 8T moiety can significantly lower the highest occupied molecular orbital (HOMO) level and leads to an enhanced open-circuit voltage because of the branched conformation. The power conversion efficiencies (PCE) of the polymer/[6,6]-phenyl-C71-butyric acid methyl ester PC71BM photovoltaic cells are in the range of 1.28-2.30%. In particular, the P8TTT-based device processed from an o-dichlorobenzene/1,8- diiodoctane mixed solvent shows the best PCE among the studied polymers (2.81%), demonstrating that 8T-based polymers with a low HOMO level can emerge as promising candidates for organic device applications. Biaxially extended octithiophene (8T)-based polymers are developed with selenophene, thiophene, and thieno[3,2-b]thiophene moieties. The designed polymers possess low highest occupied molecular orbital (HOMO) levels, leading to an enhanced open-circuit voltage and solar-cell efficiency up to 2.81%. The results demonstrate that 8T-based polymers can enhance the optoelectronic properties and device performance through their branched molecular design. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Subjects
biaxially extended materials; branched thiophene side chains; conjugated polymers; high open-circuit voltage; photovoltaic cells
SDGs
Other Subjects
Conjugated polymers; Open circuit voltage; Photoelectrochemical cells; Photovoltaic cells; Based conjugated polymers; Conjugated copolymers; Device performance; Highest occupied molecular orbital; Optoelectronic properties; Power conversion efficiencies; Side-chains; Stille coupling reaction; Thiophene
Type
journal article