17.1% Efficient Single-Junction Organic Solar Cells Enabled by n-Type Doping of the Bulk-Heterojunction

Yuanbao Lin, Yuliar Firdaus, Mohamad Insan Nugraha, Feng Liu, Safakath Karuthedath, Abdul-Hamid M. Emwas, Weimin Zhang, Akmaral Seitkhan, Marios Neophytou, Hendrik Faber, Emre Yengel, Iain McCulloch, Leonidas Tsetseris, Frédéric Laquai, Thomas D. Anthopoulos

Research output: Contribution to journalArticlepeer-review

140 Scopus citations


Molecular doping is often used in organic semiconductors to tune their (opto) electronic properties. Despite its versatility, however, its application in organic photovoltaics (OPVs) remains limited and restricted to p-type dopants. In an effort to control the charge transport within the bulk-heterojunction (BHJ) of OPVs, the n-type dopant benzyl viologen (BV) is incorporated in a BHJ composed of the donor polymer PM6 and the small-molecule acceptor IT-4F. The power conversion efficiency (PCE) of the cells is found to increase from 13.2% to 14.4% upon addition of 0.004 wt% BV. Analysis of the photoactive materials and devices reveals that BV acts simultaneously as n-type dopant and microstructure modifier for the BHJ. Under optimal BV concentrations, these synergistic effects result in balanced hole and electron mobilities, higher absorption coefficients and increased charge-carrier density within the BHJ, while significantly extending the cells’ shelf-lifetime. The n-type doping strategy is applied to five additional BHJ systems, for which similarly remarkable performance improvements are obtained. OPVs of particular interest are based on the ternary PM6:Y6:PC71BM:BV(0.004 wt%) blend for which a maximum PCE of 17.1%, is obtained. The effectiveness of the n-doping strategy highlights electron transport in NFA-based OPVs as being a key issue.
Original languageEnglish (US)
Pages (from-to)1903419
JournalAdvanced Science
StatePublished - Feb 13 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OSR-2018-CARF/CCF-3079
Acknowledgements: This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No: OSR-2018-CARF/CCF-3079. L.T. acknowledges support for the computational time granted from the GRNET facility ARIS under project STEM-2.


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