Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells

Handle URI:
http://hdl.handle.net/10754/594220
Title:
Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells
Authors:
McDowell, Caitlin; Abdelsamie, Maged ( 0000-0002-4631-5409 ) ; Zhao, Kui ( 0000-0001-9348-7943 ) ; Smilgies, Detlef M.; Bazan, Guillermo C.; Amassian, Aram ( 0000-0002-5734-1194 )
Abstract:
The addition of polystyrene (PS), a typical insulator, is empirically shown to increase the power conversion efficiencies (PCEs) of a solution-deposited bulk heterojunction (BHJ) molecular blend film used in solar cell fabrication: p-DTS(FBTTh2)2/PC71BM. The performance is further improved by small quantities of diiodooctane (DIO), an established solvent additive. In this study, how the addition of PS and DIO affects the film formation of this bulk heterojunction blend film are probed via in situ monitoring of absorbance, thickness, and crystallinity. PS and DIO additives are shown to promote donor crystallite formation on different time scales and through different mechanisms. PS-containing films retain chlorobenzene solvent, extending evaporation time and promoting phase separation earlier in the casting process. This extended time is insufficient to attain the morphology for optimal PCE results before the film sets. Here is where the presence of DIO comes into play: its low vapor pressure further extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase long after casting, ultimately leading to the best BHJ organization. In situ measurement shows that polystyrene (PS) and diiodooctane (DIO) additives promote donor crystallite formation synergistically, on different time scales, and through different mechanisms. PS-rich films retain solvent, promoting phase separation early in the casting process. Meanwhile, the low vapor pressure of DIO extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase after casting. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
KAUST Department:
Materials Science and Engineering Program; Physical Sciences and Engineering (PSE) Division
Citation:
McDowell C, Abdelsamie M, Zhao K, Smilgies D-M, Bazan GC, et al. (2015) Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells. Adv Energy Mater 5: n/a–n/a. Available: http://dx.doi.org/10.1002/aenm.201501121.
Publisher:
Wiley-Blackwell
Journal:
Advanced Energy Materials
Issue Date:
14-Jul-2015
DOI:
10.1002/aenm.201501121
Type:
Article
ISSN:
1614-6832
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.authorMcDowell, Caitlinen
dc.contributor.authorAbdelsamie, Mageden
dc.contributor.authorZhao, Kuien
dc.contributor.authorSmilgies, Detlef M.en
dc.contributor.authorBazan, Guillermo C.en
dc.contributor.authorAmassian, Aramen
dc.date.accessioned2016-01-19T14:43:38Zen
dc.date.available2016-01-19T14:43:38Zen
dc.date.issued2015-07-14en
dc.identifier.citationMcDowell C, Abdelsamie M, Zhao K, Smilgies D-M, Bazan GC, et al. (2015) Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells. Adv Energy Mater 5: n/a–n/a. Available: http://dx.doi.org/10.1002/aenm.201501121.en
dc.identifier.issn1614-6832en
dc.identifier.doi10.1002/aenm.201501121en
dc.identifier.urihttp://hdl.handle.net/10754/594220en
dc.description.abstractThe addition of polystyrene (PS), a typical insulator, is empirically shown to increase the power conversion efficiencies (PCEs) of a solution-deposited bulk heterojunction (BHJ) molecular blend film used in solar cell fabrication: p-DTS(FBTTh2)2/PC71BM. The performance is further improved by small quantities of diiodooctane (DIO), an established solvent additive. In this study, how the addition of PS and DIO affects the film formation of this bulk heterojunction blend film are probed via in situ monitoring of absorbance, thickness, and crystallinity. PS and DIO additives are shown to promote donor crystallite formation on different time scales and through different mechanisms. PS-containing films retain chlorobenzene solvent, extending evaporation time and promoting phase separation earlier in the casting process. This extended time is insufficient to attain the morphology for optimal PCE results before the film sets. Here is where the presence of DIO comes into play: its low vapor pressure further extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase long after casting, ultimately leading to the best BHJ organization. In situ measurement shows that polystyrene (PS) and diiodooctane (DIO) additives promote donor crystallite formation synergistically, on different time scales, and through different mechanisms. PS-rich films retain solvent, promoting phase separation early in the casting process. Meanwhile, the low vapor pressure of DIO extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase after casting. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.en
dc.publisherWiley-Blackwellen
dc.subjectbulk heterojunction (BHJ) solar cellsen
dc.subjectpolymer additive processingen
dc.subjectsolution processable small moleculesen
dc.subjectsolvent additive processingen
dc.subjectthin film morphologyen
dc.titleSynergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cellsen
dc.typeArticleen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalAdvanced Energy Materialsen
dc.contributor.institutionCenter for Energy Efficient Materials; Department of Chemistry and Biochemistry, Department of Materials; Center for Polymers and Organic Solids; University of California; Santa Barbara CA 93106 USAen
dc.contributor.institutionCornell High Energy Synchrotron Source; Cornell University; Ithaca NY 14850 USAen
kaust.authorAbdelsamie, Mageden
kaust.authorZhao, Kuien
kaust.authorAmassian, Aramen
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