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Multiple Charge Transfer States in Donor−Acceptor Heterojunctions with Large Frontier Orbital Energy Offsets

dc.rights.licenseopen
dc.contributor.authorKHAN, Saeed-Uz-Zaman
hal.structure.identifierDepartment of Chemistry “Ugo Schiff”
dc.contributor.authorLONDI, Giacomo
dc.contributor.authorLIU, Xiao
dc.contributor.authorFUSELLA, Michael
dc.contributor.authorAVINO, Gabriele
hal.structure.identifierLaboratoire de Chimie des Polymères Organiques [LCPO]
dc.contributor.authorMUCCIOLI, Luca
dc.contributor.authorBRIGEMAN, Alyssa
dc.contributor.authorNIESEN, Bjoern
dc.contributor.authorCHIEN, Terry
dc.contributor.authorYANG, Jen
hal.structure.identifierUniv Mons, Lab Chem Novel Mat, Belgium
dc.contributor.authorOLIVIER, Yoann
dc.contributor.authorDULL, Jordan
dc.contributor.authorGIEBINK, Noel
hal.structure.identifierLaboratory for Chemistry of Novel Materials
dc.contributor.authorBELJONNE, David
dc.contributor.authorRAND, Barry
dc.date.accessioned2020
dc.date.available2020
dc.date.issued2019
dc.identifier.issn0897-4756
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/19761
dc.description.abstractEnIn this work, we demonstrate several organic amorphous donor−acceptor systems that exhibit sub-bandgap features over a more than 2 eV spectral range. An in-depth study of one of these systems, NPB:HAT-CN (NPB is N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine and HAT-CN is 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile), reveals that the broad sub-bandgap features are attributed to multiple electronic charge transfer (CT) state transitions, broadened by energetic disorder sourcing from the fluctuations of intramolecular conformations and by the disordered intermolecular environment. These unique CT features originate from an unconventional donor and acceptor selection that reveals new insight about photocurrent generation and nonradiative recombination. Unlike materials employed in high performing organic solar cells, the materials studied here feature large optical energy gaps with very large frontier orbital energy level offsets, creating high bandgap devices with low open-circuit voltage. In addition to multiple electronic CT levels, we reveal that the internal quantum efficiency of these multiple CT transitions is not constant but photon energy dependent and with photoluminescence that originates primarily from the second lowest electronic CT state implying slow (relative to radiative and nonradiative rates) internal conversion within the CT manifold. Overall, this class of donor−acceptor pairs provides an opportunity to probe CT states in unique ways to potentially unravel their role in carrier generation−recombination and energy loss mechanisms. ■ INTRODUCTION With more than 15% power conversion efficiency recently achieved 1 and coupled with the ability to be grown on flexible substrates on a large scale with low-cost fabrication techniques, organic solar cells are making a strong case for energy conversion applications. Most advances in power conversion efficiency are the result of impressive material and interface engineering and innovation. However, due to the lack of a complete understanding and consensus of carrier generation and recombination processes as well as loss mechanisms at charge generating donor−acceptor (D-A) interfaces, 2 the actual limits of organic solar cell performance remain unknown. In this context, intermolecular charge transfer (CT) excitations at D−A interfaces play an important role in the photophysical processes and energy losses of organic solar cells. 3−6 In order to understand how carrier generation and recombination are affected by CT states, a better comprehension of their origin and energetic distribution is crucial. More specifically, some key issues that are currently under inquiry include whether the carrier dissociation efficiency Special Issue: Jean-Luc Bredas Festschrift
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.title.enMultiple Charge Transfer States in Donor−Acceptor Heterojunctions with Large Frontier Orbital Energy Offsets
dc.typeArticle de revue
dc.identifier.doi10.1021/acs.chemmater.9b01279
dc.subject.halChimie/Matériaux
dc.subject.halPhysique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
bordeaux.journalChemistry of Materials
bordeaux.page6808 - 6817
bordeaux.volume31
bordeaux.hal.laboratoriesLaboratoire de Chimie des Polymères Organiques (LCPO) - UMR 5629*
bordeaux.institutionBordeaux INP
bordeaux.institutionUniversité de Bordeaux
bordeaux.peerReviewedoui
hal.identifierhal-02399119
hal.version1
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-02399119v1
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Chemistry%20of%20Materials&rft.date=2019&rft.volume=31&rft.spage=6808%20-%206817&rft.epage=6808%20-%206817&rft.eissn=0897-4756&rft.issn=0897-4756&rft.au=KHAN,%20Saeed-Uz-Zaman&LONDI,%20Giacomo&LIU,%20Xiao&FUSELLA,%20Michael&AVINO,%20Gabriele&rft.genre=article


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