Comparison of the Photovoltaic Characteristics and Nanostructure of Fullerenes Blended with Conjugated Polymers with Siloxane-Terminated and Branched Aliphatic Side Chains

Handle URI:
http://hdl.handle.net/10754/597815
Title:
Comparison of the Photovoltaic Characteristics and Nanostructure of Fullerenes Blended with Conjugated Polymers with Siloxane-Terminated and Branched Aliphatic Side Chains
Authors:
Kim, Do Hwan; Ayzner, Alexander L.; Appleton, Anthony L.; Schmidt, Kristin; Mei, Jianguo; Toney, Michael F.; Bao, Zhenan
Abstract:
All-organic bulk heterojunction solar cells based on blends of conjugated polymers with fullerenes have recently surpassed the 8% efficiency mark and are well on their way to the industrially relevant ∼15% threshold. Using a low band-gap conjugated polymer, we have recently shown that polymer side chain engineering can lead to dramatic improvement in the in-plane charge carrier mobility. In this article, we investigate the effectiveness of siloxy side chain derivatization in controlling the photovoltaic performance of polymer:[6,6]-phenyl-C[71]-butyric acid methyl ester (PC71BM) blends and hence its influence on charge transport in the out-of-plane direction relevant for organic solar cells. We find that, in neat blends, the photocurrent of the polymer with siloxy side chains (PII2T-Si) is 4 times greater than that in blends using the polymer with branched aliphatic side chains (PII2T-ref). This difference is due to a larger out-of-plane hole mobility for PII2T-Si brought about by a largely face-on crystallite orientation as well as more optimal nanoscale polymer:PC71BM mixing. However, upon incorporating a common processing additive, 1,8-diiodooctane (DIO), into the spin-casting blend solution and following optimization, the PII2T-ref:PC71BM OPV device performance undergoes a large improvement and becomes the better-performing device, almost independent of DIO concentration (>1%). We find that the precise amount of DIO plays a larger role in determining the efficiency of PII2T-Si:PC71BM, and even at its maximum, the device performance lags behind optimized PII2T-ref:PC71BM blends. Using a combination of atomic force microscopy and small- and wide-angle X-ray scattering, we are able to elucidate the morphological modifications associated with the DIO-induced changes in both the nanoscale morphology and the molecular packing in blend films. © 2012 American Chemical Society.
Citation:
Kim DH, Ayzner AL, Appleton AL, Schmidt K, Mei J, et al. (2013) Comparison of the Photovoltaic Characteristics and Nanostructure of Fullerenes Blended with Conjugated Polymers with Siloxane-Terminated and Branched Aliphatic Side Chains. Chem Mater 25: 431–440. Available: http://dx.doi.org/10.1021/cm303572d.
Publisher:
American Chemical Society (ACS)
Journal:
Chemistry of Materials
KAUST Grant Number:
KUS-C1-015-21
Issue Date:
12-Feb-2013
DOI:
10.1021/cm303572d
Type:
Article
ISSN:
0897-4756; 1520-5002
Sponsors:
This work was partially supported by the Center for Advanced Molecular Photovoltaics, award no. KUS-C1-015-21, made by King Abdullah University of Science and Technology. We also acknowledge support from the Global Climate and Energy Program at Stanford and the Camille and Henry Dreyfus Postdoctoral Program in Environmental Chemistry. GIXD measurements were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.
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DC FieldValue Language
dc.contributor.authorKim, Do Hwanen
dc.contributor.authorAyzner, Alexander L.en
dc.contributor.authorAppleton, Anthony L.en
dc.contributor.authorSchmidt, Kristinen
dc.contributor.authorMei, Jianguoen
dc.contributor.authorToney, Michael F.en
dc.contributor.authorBao, Zhenanen
dc.date.accessioned2016-02-25T12:57:11Zen
dc.date.available2016-02-25T12:57:11Zen
dc.date.issued2013-02-12en
dc.identifier.citationKim DH, Ayzner AL, Appleton AL, Schmidt K, Mei J, et al. (2013) Comparison of the Photovoltaic Characteristics and Nanostructure of Fullerenes Blended with Conjugated Polymers with Siloxane-Terminated and Branched Aliphatic Side Chains. Chem Mater 25: 431–440. Available: http://dx.doi.org/10.1021/cm303572d.en
dc.identifier.issn0897-4756en
dc.identifier.issn1520-5002en
dc.identifier.doi10.1021/cm303572den
dc.identifier.urihttp://hdl.handle.net/10754/597815en
dc.description.abstractAll-organic bulk heterojunction solar cells based on blends of conjugated polymers with fullerenes have recently surpassed the 8% efficiency mark and are well on their way to the industrially relevant ∼15% threshold. Using a low band-gap conjugated polymer, we have recently shown that polymer side chain engineering can lead to dramatic improvement in the in-plane charge carrier mobility. In this article, we investigate the effectiveness of siloxy side chain derivatization in controlling the photovoltaic performance of polymer:[6,6]-phenyl-C[71]-butyric acid methyl ester (PC71BM) blends and hence its influence on charge transport in the out-of-plane direction relevant for organic solar cells. We find that, in neat blends, the photocurrent of the polymer with siloxy side chains (PII2T-Si) is 4 times greater than that in blends using the polymer with branched aliphatic side chains (PII2T-ref). This difference is due to a larger out-of-plane hole mobility for PII2T-Si brought about by a largely face-on crystallite orientation as well as more optimal nanoscale polymer:PC71BM mixing. However, upon incorporating a common processing additive, 1,8-diiodooctane (DIO), into the spin-casting blend solution and following optimization, the PII2T-ref:PC71BM OPV device performance undergoes a large improvement and becomes the better-performing device, almost independent of DIO concentration (>1%). We find that the precise amount of DIO plays a larger role in determining the efficiency of PII2T-Si:PC71BM, and even at its maximum, the device performance lags behind optimized PII2T-ref:PC71BM blends. Using a combination of atomic force microscopy and small- and wide-angle X-ray scattering, we are able to elucidate the morphological modifications associated with the DIO-induced changes in both the nanoscale morphology and the molecular packing in blend films. © 2012 American Chemical Society.en
dc.description.sponsorshipThis work was partially supported by the Center for Advanced Molecular Photovoltaics, award no. KUS-C1-015-21, made by King Abdullah University of Science and Technology. We also acknowledge support from the Global Climate and Energy Program at Stanford and the Camille and Henry Dreyfus Postdoctoral Program in Environmental Chemistry. GIXD measurements were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.en
dc.publisherAmerican Chemical Society (ACS)en
dc.subjectDIOen
dc.subjectmolecular packingen
dc.subjectorganic photovoltaicsen
dc.subjectsiloxane side chainen
dc.subjectthin-film morphologyen
dc.subjectX-ray scatteringen
dc.titleComparison of the Photovoltaic Characteristics and Nanostructure of Fullerenes Blended with Conjugated Polymers with Siloxane-Terminated and Branched Aliphatic Side Chainsen
dc.typeArticleen
dc.identifier.journalChemistry of Materialsen
dc.contributor.institutionStanford University, Palo Alto, United Statesen
dc.contributor.institutionStanford Synchrotron Radiation Laboratory, Menlo Park, United Statesen
dc.contributor.institutionSoongsil University, Seoul, South Koreaen
kaust.grant.numberKUS-C1-015-21en
kaust.grant.fundedcenterCenter for Advanced Molecular Photovoltaics (CAMP)en
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