title: One-Step Synthesis of Precursor Oligomers for Organic Photovoltaics: A Comparative Study between Polymers and Small Molecules.
abstract: Two series of oligomers TQ and rhodanine end-capped TQ-DR were synthesized using a facile one-step method. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated and compared. The TQ series of oligomers were found to be amorphous, whereas the TQ-DR series are semicrystalline. For the TQ oligomers, the results obtained in solar cells show that as the chain length of the oligomers increases, an increase in power conversion efficiency (PCE) is obtained. However, when introducing 3-ethylrhodanine into the TQ oligomers as end groups, the PCE of the TQ-DR series of oligomers decreases as the chain length increases. Moreover, the TQ-DR series of oligomers give much higher performances compared to the original amorphous TQ series of oligomers owing to the improved extinction coefficient (ε) and crystallinity afforded by the rhodanine. In particular, the highly crystalline oligomer TQ5-DR, which has the shortest conjugation length shows a high hole mobility of 0.034 cm(2) V(-1) s(-1) and a high PCE of 3.14%, which is the highest efficiency out of all of the six oligomers. The structure-property correlations for all of the oligomers and the TQ1 polymer demonstrate that structural control of enhanced intermolecular interactions and crystallinity is a key for small molecules/oligomers to achieve high mobilities, which is an essential requirement for use in OPVs.
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Göteborg, Sweden.|Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Biomolecular and Organic Electronics, IFM, Linköping University , SE-58183 Linköping, Sweden.
authors.forename: Daojuan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Laboratory of Organic Electronics, Department of Science and Technology, Linköping University , SE-60174 Norrköping, Sweden.
authors.forename: Suhao
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University , Xi'an 710049, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.affiliation: Division of Theoretical Chemistry, Lund University , SE-221 00 Lund, Sweden.
authors.forename: Svante
authors.initials: S
authors.lastname: Hedström
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Göteborg, Sweden.
authors.forename: David Ian
authors.initials: DI
authors.lastname: James
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Göteborg, Sweden.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Xu
authors.affiliation: Division of Theoretical Chemistry, Lund University , SE-221 00 Lund, Sweden.
authors.forename: Petter
authors.initials: P
authors.lastname: Persson
authors.affiliation: Laboratory of Organic Electronics, Department of Science and Technology, Linköping University , SE-60174 Norrköping, Sweden.
authors.forename: Simone
authors.initials: S
authors.lastname: Fabiano
authors.affiliation: Laboratory of Organic Electronics, Department of Science and Technology, Linköping University , SE-60174 Norrköping, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Berggren
authors.affiliation: Biomolecular and Organic Electronics, IFM, Linköping University , SE-58183 Linköping, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Inganäs
authors.affiliation: Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, P. R. China.
authors.forename: Fei
authors.initials: F
authors.lastname: Huang
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Göteborg, Sweden.
authors.forename: Ergang
authors.initials: E
authors.lastname: Wang
keywords: amorphous; crystallinity; hole mobility; oligomers; one-step method; organic photovoltaics