Gaining Further Insight into the Solvent Additive-Driven Crystallization of Bulk-Heterojunction Solar Cells by <i>in Situ</i> X-ray Scattering and Optical Reflectometry

Buss, Felix; Schmidt‐Hansberg, Benjamin; Sanyal, Monamie; Munuera, Carmen; Scharfer, Philip; Schabel, Wilhelm; Barrena, Esther

doi:10.1021/acs.macromol.6b00193

Cited by 22 publications

(20 citation statements)

References 43 publications

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“…At present, the majority of solution‐processed BHJ OPV active layers are deposited via spin casting, and thus in situ morphology studies have largely probed BHJ evolution during spin casting . While convenient at lab scale, this technique is not likely to be scalable to large area modules .…”

Section: Mechanistic Understanding Of Solvent Additive Effects On Bhjmentioning

confidence: 99%

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

et al. 2018

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Organic photovoltaics (OPV) have the advantage of possible fabrication by energy-efficient and cost-effective deposition methods, such as solution processing. Solvent additives can provide fine control of the active layer morphology of OPVs by influencing film formation during solution processing. As such, solvent additives form a versatile method of experimental control for improving organic solar cell device performance. This review provides a brief history of solution-processed bulk heterojunction OPVs and the advent of solvent additives, putting them into context with other methods available for morphology control. It presents the current understanding of how solvent additives impact various mechanisms of phase separation, enabled by recent advances in in situ morphology characterization. Indeed, understanding solvent additives' effects on film formation has allowed them to be applied and combined effectively and synergistically to boost OPV performance. Their success as a morphology control strategy has also prompted the use of solvent additives in related organic semiconductor technologies. Finally, the role of solvent additives in the development of next-generation OPV active layers is discussed. Despite concerns over their environmental toxicity and role in device instability, solvent additives remain relevant morphological directing agents as research interests evolve toward nonfullerene acceptors, ternary blends, and environmentally sustainable solvents.

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Section: Mechanistic Understanding Of Solvent Additive Effects On Bhjmentioning

confidence: 99%

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

et al. 2018

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“…In blend films, the greatest change is that all X-ray scattering peaks broadened, with the appearance of an additional reflection at q xy,z = $ 2.2 Å À1 ; this was attributed to the presence of nanoscale PC 71 BM aggregates [Figs. 4(c)-4(f)] (Buss et al, 2016). Also, according to crystalline domain size results, the SM1 crystal was larger in size (9.013 Å ) than SM2 crystallites (6.054 Å ) in mixture films, which means that the larger crystalline phase structures of Solar cell device performances and carrier mobility properties in DPP-based small-molecule (SM) photovoltaics.…”

Section: Resultsmentioning

confidence: 95%

Markedly different molecular formation in DPP-based small-molecule solar cells probed by grazing-incidence wide-angle X-ray scattering

Kim

Song

Suranagi

et al. 2017

Acta Crystallogr Sect B

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This study comprehensively explores the nanostructural properties of two diketopyrrolo[3,4-c]pyrrole-1,4-dione (DPP)-based small molecules with different alkyl side groups and their blends with the fullerene derivative PCBM, using grazing-incidence wide-angle X-ray scattering synchrotron techniques. Preferentially relative face-on orientation within the larger and more ordered stacking phase of SM1 with its shorter side group (ethylhexyl) was observed in the majority of both pristine and blend thin films, whereas SM2 crystals showed strictly perpendicular orientation. These contrasting crystalline characteristics led to significant differences in the results, from which crystalline structure-performance property correlations are proposed. Thus, the results not only demonstrate important scientific insights into the relationship between molecular structure and crystalline formation but also provide molecular design directions that will facilitate further improvement to the morphology and performance of DPP-based small-molecule solar cells.

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“…Buss and coworkers studied blade coating of PCPDTBT and PC71BM and focused on the role of 1,8-octanedithiol (ODT) in the crystallization. [143] ODT was found to prolong the crystallization time during the ODTdrying dominated period. In addition, it delayed the onset of PC71BM aggregation, being pushed out of the crystalline poly mer domains.…”

Section: Wwwadvancedsciencenewscommentioning

confidence: 95%

π‐Conjugated Donor Polymers: Structure Formation and Morphology in Solution, Bulk and Photovoltaic Blends

Hildner

Köhler

Müller‐Buschbaum

et al. 2017

Advanced Energy Materials

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The field of conjugated polymers has expanded in the last years considerably and impressive performance, both in field effect transistors and photovoltaic devices has been achieved. After the initial emphasis on improving the performance, more emphasis is recently given to fundamental studies on structure formation. Therefore, this review concentrates on systematic correlation studies of structure formation in solution, in bulk and thin films as well as in photovoltaic blends of donor‐type π‐conjugated polymers. The main focus is on the correlation of structure, morphology and molecular chain orientation as a function of macromolecular properties such as molecular weight, dispersity, non‐covalent intramolecular and intermolecular interactions, solvent interactions and innovative processing techniques. The tools applied for elucidating fundamental information of structure formation and orientation mainly consist of optical spectroscopy and scattering techniques (SAXS/WAXS/GIWAXS). Since the field of conjugated polymers is very vast in terms of chemical structural diversity, only selected examples of donor polymers are covered here and the emerging class of n‐type conjugated polymers are not included. The focus is not on the structural variation or their performance in solar cells or transistors in terms of record efficiencies, but on the systematic studies leading to a structure‐property correlation in donor polymers.

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Gaining Further Insight into the Solvent Additive-Driven Crystallization of Bulk-Heterojunction Solar Cells by in Situ X-ray Scattering and Optical Reflectometry

Cited by 22 publications

References 43 publications

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

Markedly different molecular formation in DPP-based small-molecule solar cells probed by grazing-incidence wide-angle X-ray scattering

π‐Conjugated Donor Polymers: Structure Formation and Morphology in Solution, Bulk and Photovoltaic Blends

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