title: Chalcogenophene comonomer comparison in small band gap diketopyrrolopyrrole-based conjugated polymers for high-performing field-effect transistors and organic solar cells.
abstract: The design, synthesis, and characterization of a series of diketopyrrolopyrrole-based copolymers with different chalcogenophene comonomers (thiophene, selenophene, and tellurophene) for use in field-effect transistors and organic photovoltaic devices are reported. The effect of the heteroatom substitution on the optical, electrochemical, and photovoltaic properties and charge carrier mobilities of these polymers is discussed. The results indicate that by increasing the size of the chalcogen atom (S < Se < Te), polymer band gaps are narrowed mainly due to LUMO energy level stabilization. In addition, the larger heteroatomic size also increases intermolecular heteroatom-heteroatom interactions facilitating the formation of polymer aggregates leading to enhanced field-effect mobilities of 1.6 cm(2)/(V s). Bulk heterojunction solar cells based on the chalcogenophene polymer series blended with fullerene derivatives show good photovoltaic properties, with power conversion efficiencies ranging from 7.1-8.8%. A high photoresponse in the near-infrared (NIR) region with excellent photocurrents above 20 mA cm(-2) was achieved for all polymers, making these highly efficient low band gap polymers promising candidates for use in tandem solar cells.
authors.affiliation: Department of Chemistry and Centre for Plastic Electronics, Imperial College London , London SW7 2AZ, United Kindgom.
authors.forename: Raja Shahid
authors.initials: RS
authors.lastname: Ashraf
authors.forename: Iain
authors.initials: I
authors.lastname: Meager
authors.forename: Mark
authors.initials: M
authors.lastname: Nikolka
authors.forename: Mindaugas
authors.initials: M
authors.lastname: Kirkus
authors.forename: Miquel
authors.initials: M
authors.lastname: Planells
authors.forename: Bob C
authors.initials: BC
authors.lastname: Schroeder
authors.forename: Sarah
authors.initials: S
authors.lastname: Holliday
authors.forename: Michael
authors.initials: M
authors.lastname: Hurhangee
authors.forename: Christian B
authors.initials: CB
authors.lastname: Nielsen
authors.forename: Henning
authors.initials: H
authors.lastname: Sirringhaus
authors.forename: Iain
authors.initials: I
authors.lastname: McCulloch