Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics

Nicholas D. Eastham; Alexander S. Dudnik; Boris Harutyunyan; Thomas J. Aldrich; Matthew J. Leonardi; Eric F. Manley; Melanie R. Butler; Tobias Harschneck; Mark A Ratner; Lin X. Chen; Michael J. Bedzyk; Ferdinand S. Melkonyan; Antonio Facchetti; Robert P. H. Chang; Tobin J Marks

doi:10.1021/acsenergylett.7b00486

Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics

Nicholas D. Eastham, Alexander S. Dudnik, Boris Harutyunyan, Thomas J. Aldrich, Matthew J. Leonardi, Eric F. Manley, Melanie R. Butler, Tobias Harschneck, Mark A Ratner, Lin X. Chen, Michael J. Bedzyk, Ferdinand S. Melkonyan, Antonio Facchetti, Robert P. H. Chang, Tobin J Marks

Northwestern University

Research output: Contribution to journal › Article › peer-review

25 Citations (Scopus)

Abstract

Using small-molecule donor (SMD) semiconductors in organic photovoltaics (OPVs) has historically afforded lower power conversion efficiencies (PCEs) than their polymeric counterparts. The PCE difference is attributed to shorter conjugated backbones, resulting in reduced intermolecular interactions. Here, a new pair of SMDs is synthesized based on the diketopyrrolopyrrole-benzodithiophene-diketopyrrolopyrrole (BDT-DPP₂) skeleton but having fluorinated and fluorine-free aromatic side-chain substituents. Ternary OPVs having varied ratios of the two SMDs with PC₆₁BM as the acceptor exhibit tunable open-circuit voltages (V_ocs) between 0.833 and 0.944 V due to a fluorination-induced shift in energy levels and the electronic "alloy" formed from the miscibility of the two SMDs. A 15% increase in PCE is observed at the optimal ternary SMD ratio, with the short-circuit current density (J_sc) significantly increased to 9.18 mA/cm². The origin of J_sc enhancement is analyzed via charge generation, transport, and diffuse reflectance measurements, and is attributed to increased optical absorption arising from a maximum in film crystallinity at this SMD ratio, observed by grazing incidence wide-angle X-ray scattering.

Original language	English
Pages (from-to)	1690-1697
Number of pages	8
Journal	ACS Energy Letters
Volume	2
Issue number	7
DOIs	https://doi.org/10.1021/acsenergylett.7b00486
Publication status	Published - Jul 14 2017

ASJC Scopus subject areas

Chemistry (miscellaneous)
Energy Engineering and Power Technology
Fuel Technology
Renewable Energy, Sustainability and the Environment
Materials Chemistry

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Eastham, N. D., Dudnik, A. S., Harutyunyan, B., Aldrich, T. J., Leonardi, M. J., Manley, E. F., Butler, M. R., Harschneck, T., Ratner, M. A., Chen, L. X., Bedzyk, M. J., Melkonyan, F. S., Facchetti, A., Chang, R. P. H., & Marks, T. J. (2017). Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics. ACS Energy Letters, 2(7), 1690-1697. https://doi.org/10.1021/acsenergylett.7b00486

Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics. / Eastham, Nicholas D.; Dudnik, Alexander S.; Harutyunyan, Boris; Aldrich, Thomas J.; Leonardi, Matthew J.; Manley, Eric F.; Butler, Melanie R.; Harschneck, Tobias; Ratner, Mark A; Chen, Lin X.; Bedzyk, Michael J.; Melkonyan, Ferdinand S.; Facchetti, Antonio; Chang, Robert P. H.; Marks, Tobin J.

In: ACS Energy Letters, Vol. 2, No. 7, 14.07.2017, p. 1690-1697.

Research output: Contribution to journal › Article › peer-review

Eastham, ND, Dudnik, AS, Harutyunyan, B, Aldrich, TJ, Leonardi, MJ, Manley, EF, Butler, MR, Harschneck, T, Ratner, MA, Chen, LX, Bedzyk, MJ, Melkonyan, FS, Facchetti, A, Chang, RPH & Marks, TJ 2017, 'Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics', ACS Energy Letters, vol. 2, no. 7, pp. 1690-1697. https://doi.org/10.1021/acsenergylett.7b00486

Eastham, Nicholas D. ; Dudnik, Alexander S. ; Harutyunyan, Boris ; Aldrich, Thomas J. ; Leonardi, Matthew J. ; Manley, Eric F. ; Butler, Melanie R. ; Harschneck, Tobias ; Ratner, Mark A ; Chen, Lin X. ; Bedzyk, Michael J. ; Melkonyan, Ferdinand S. ; Facchetti, Antonio ; Chang, Robert P. H. ; Marks, Tobin J. / Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics. In: ACS Energy Letters. 2017 ; Vol. 2, No. 7. pp. 1690-1697.

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