New donor polymer with tetrafluorinated blocks for enhanced performance in perylenediimide-based solar cells

Amod Timalsina, Patrick E. Hartnett, Ferdinand S. Melkonyan*, Joseph Strzalka, Vari S. Reddy, Antonio Facchetti, Michael R. Wasielewski, Tobin J. Marks

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

The synthesis of a new tetrafluorinated semiconducting donor polymer, poly[(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)-benzo[1,2-b:4,5-b′]dithiophene)-alt-(5,6-difluoro-4,7-(4-(2-ethylhexyl)-dithien-2-yl-2,1,3-benzothiadiazole)] (PBTZF4), and its photovoltaic performance in bulk heterojunction (BHJ) blends with the non-fullerene molecular acceptor [1,2:3,4]-bis-[N,N′-bis-1-pentylhexyl-perylenediimide-1,12-yl]-benzene (bPDI2P), are reported. PBTZF4:bPDI2P solar cells exhibit a high open circuit voltage (Voc) of 1.118 V, a short circuit current density (Jsc) of 10.02 mA cm−2, and a fill factor (FF) of 49.5%, affording a power conversion efficiency (PCE) of 5.55%. Interestingly, a lower PCE of 3.68% is obtained with the difluorinated analogue, poly[(4,8-bis(5-(2-ethylhexyl)-thiophene-2-yl)-benzo[1,2-b:4,5-b′]dithiophene)-alt-(5,6-difluoro-4,7-(4-(2-ethyl-hexyl)-dithien-2-yl-2,1,3-benzothiadiazole)] (PBTZF2). Both PBTZF4:bPDI2P and PBTZF2:bPDI2P cells benefit from complementary (donor/acceptor) light absorption and very low geminate recombination, with bimolecular recombination being the dominant loss mechanism, as established by femtosecond transient absorption spectroscopy. DFT computation and physicochemical characterization data argue that the “additional” tetrafluorination planarizes the PBTZF4 backbone and enhances aggregation versusPBTZF2, affording superior charge carrier transport as assayed by field-effect mobility. In addition, fluorine-originated HOMO stabilization, −5.41 eV for PBTZF4versus −5.33 eV for PBTZF2, and a superior blend microstructure afford a higher PBTZF4:bPDI2P solar cell PCE versusPBTZF2:bPDI2P.

Original languageEnglish (US)
Pages (from-to)5351-5361
Number of pages11
JournalJournal of Materials Chemistry A
Volume5
Issue number11
DOIs
StatePublished - 2017

Funding

This work was supported by the Argonne-Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, under award number DE-SC0001059 (A. T. for polymer synthesis and OPV characterization, P. E. H. for acceptor synthesis and spectroscopy). This work was also supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Award Number DE-FG02-08ER46536. V. S. R. thanks the Indo-US Science & Technology Forum (IUSSTF) for BASE fellowship. F. S. M. was supported by award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD). Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.

ASJC Scopus subject areas

  • General Chemistry
  • Renewable Energy, Sustainability and the Environment
  • General Materials Science

Fingerprint

Dive into the research topics of 'New donor polymer with tetrafluorinated blocks for enhanced performance in perylenediimide-based solar cells'. Together they form a unique fingerprint.

Cite this