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Correlated In Situ Low‐Frequency Noise and Impedance Spectroscopy Reveal Recombination Dynamics in Organic Solar Cells Using Fullerene and Non‐Fullerene Acceptors
Author(s) -
Luck Kyle A.,
Sangwan Vinod K.,
Hartnett Patrick E.,
Arnold Heather N.,
Wasielewski Michael R.,
Marks Tobin J.,
Hersam Mark C.
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201703805
Subject(s) - organic solar cell , materials science , fullerene , acceptor , chemical physics , polymer solar cell , dielectric spectroscopy , spectroscopy , noise (video) , optoelectronics , analytical chemistry (journal) , solar cell , chemistry , physics , electrode , condensed matter physics , polymer , organic chemistry , image (mathematics) , electrochemistry , quantum mechanics , artificial intelligence , computer science , composite material
Non‐fullerene acceptors based on perylenediimides (PDIs) have garnered significant interest as an alternative to fullerene acceptors in organic photovoltaics (OPVs), but their charge transport phenomena are not well understood, especially in bulk heterojunctions (BHJs). Here, charge transport and current fluctuations are investigated by performing correlated low‐frequency noise and impedance spectroscopy measurements on two BHJ OPV systems, one employing a fullerene acceptor and the other employing a dimeric PDI acceptor. In the dark, these measurements reveal that PDI‐based OPVs have a greater degree of recombination in comparison to fullerene‐based OPVs. Furthermore, for the first time in organic solar cells, 1/ f noise data are fit to the Kleinpenning model to reveal underlying current fluctuations in different transport regimes. Under illumination, 1/ f noise increases by approximately four orders of magnitude for the fullerene‐based OPVs and three orders of magnitude for the PDI‐based OPVs. An inverse correlation is also observed between noise spectral density and power conversion efficiency. Overall, these results show that low‐frequency noise spectroscopy is an effective in situ diagnostic tool to assess charge transport in emerging photovoltaic materials, thereby providing quantitative guidance for the design of next‐generation solar cell materials and technologies.