Impact of Nonfullerene Acceptor Core Structure on the Photophysics and Efficiency of Polymer Solar Cells
Khan, Jafar Iqbal
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
Materials Science and Engineering Program
KAUST Solar Center (KSC)
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AbstractSmall-molecule “nonfullerene” acceptors are promising alternatives to fullerene (PC61/71BM) derivatives often used in bulk heterojunction (BHJ) organic solar cells; yet, the efficiency-limiting processes and their dependence on the acceptor structure are not clearly understood. Here, we investigate the impact of the acceptor core structure (cyclopenta-[2,1-b:3,4-b′]dithiophene (CDT) versus indacenodithiophene (IDTT)) of malononitrile (BM)-terminated acceptors, namely CDTBM and IDTTBM, on the photophysical characteristics of BHJ solar cells. Using PCE10 as donor polymer, the IDTT-based acceptor achieves power conversion efficiencies (8.4%) that are higher than those of the CDT-based acceptor (5.6%) because of a concurrent increase in short-circuit current and open-circuit voltage. Using (ultra)fast transient spectroscopy we demonstrate that reduced geminate recombination in PCE10:IDTTBM blends is the reason for the difference in short-circuit currents. External quantum efficiency measurements indicate that the higher energy of interfacial charge-transfer states observed for the IDTT-based acceptor blends is the origin of the higher open-circuit voltage.
CitationAlamoudi MA, Khan JI, Firdaus Y, Wang K, Andrienko D, et al. (2018) Impact of Nonfullerene Acceptor Core Structure on the Photophysics and Efficiency of Polymer Solar Cells. ACS Energy Letters: 802–811. Available: http://dx.doi.org/10.1021/acsenergylett.8b00045.
SponsorsThe research reported in this publication was supported by the Office of Sponsored Research (OSR) under the Grant Agreement FCS/1/3321/01 and by the King Abdullah University of Science and Technology (KAUST). M.A.A. is grateful to Saudi Basic Industries Corporation (SABIC) for funding received towards the Ph.D.
PublisherAmerican Chemical Society (ACS)
JournalACS Energy Letters