Charge Transport Orthogonality in All‐Polymer Blend Transistors, Diodes, and Solar Cells

Fabiano, Simone; Himmelberger, Scott; Drees, Martin; Chen, Zhihua; Altamimi, Rashid M.; Salleo, Alberto; Loi, Maria Antonietta; Facchetti, Antonio

doi:10.1002/aenm.201301409

Cited by 65 publications

(65 citation statements)

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“…Indeed, P(NDI2OD-T2) with a low surface energy (23.7 mJ·m -2 ; ref. 23) tends to segregate at the air/film interface, whereas PS with higher surface energy (40.2 mJ·m -2 ; ref. 27) prefers the SiO 2 surface.…”

Section: Resultsmentioning

confidence: 99%

“…In a recent publication, Neher and coworkers also showed that this polymer has a strong tendency to aggregate, which greatly affects the bulk optical and electrical properties (20,21). Control of the preaggregation of this polymer in solution has shown great promise for the optimization of all-polymer solar cells in which P(NDI2OD-T2) is used as a fullerene replacement (22,23). Although several reports have investigated charge transport of P(NDI2OD-T2) in solution-processed thin films as a function of the processing conditions, the results are often qualitative and a complete description of how charges propagate across the ordered and disordered regions is needed.…”

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confidence: 99%

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Experimental evidence that short-range intermolecular aggregation is sufficient for efficient charge transport in conjugated polymers

Wang

Fabiano

Himmelberger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Efficiency, current throughput, and speed of electronic devices are to a great extent dictated by charge carrier mobility. The classic approach to impart high carrier mobility to polymeric semiconductors has often relied on the assumption that extensive order and crystallinity are needed. Recently, however, this assumption has been challenged, because high mobility has been reported for semiconducting polymers that exhibit a surprisingly low degree of order. Here, we show that semiconducting polymers can be confined into weakly ordered fibers within an inert polymer matrix without affecting their charge transport properties. In these conditions, the semiconducting polymer chains are inhibited from attaining longrange order in the π-stacking or alkyl-stacking directions, as demonstrated from the absence of significant X-ray diffraction intensity corresponding to these crystallographic directions, yet still remain extended along the backbone direction and aggregate on a local length scale. As a result, the polymer films maintain high mobility even at very low concentrations. Our findings provide a simple picture that clarifies the role of local order and connectivity of domains.organic electronics | conjugated polymers | aggregation | charge transport C onjugated polymers have received significant scientific attention as the active material in devices for printed and flexible organic electronics (1, 2). Owing to their versatile chemical synthesis, inexpensive processability from solution, and unique mechanical flexibility, these materials are in fact promising for a vast array of devices in future low-cost and distributed technologies, such as integrated systems for electronic labels targeting safety, security, and surveillance applications (3). The rational design of new organic semiconductors has been guided by a thorough investigation of their limitations in charge transport, leading to the development of high-performance materials for next-generation electronic applications such as low-cost displays, solar cells, sensors, and logic circuits (4, 5). For more than a decade research has primarily focused on increasing the long-range order and the crystallinity of conjugated polymers as a strategy to improve the solid-state charge transport properties. As a result, the charge carrier mobility has increased by several orders of magnitude through the design and synthesis of highly ordered polymers. However, recent studies have suggested that the key to designing high-mobility polymers is not to increase their crystallinity but rather to improve their tolerance for disorder by allowing more efficient intra-and intermolecular charge transport pathways (6). This observation explains why mobility values obtained from recently designed seemingly disordered organic semiconductors often exceed those of polymers having a high degree of crystallinity (∼1 cm 2 ·V -1 ·s -1 ) (7-10). Indeed, polymers may exhibit little longrange order, as measured by X-ray diffraction (XRD), and yet display a remarkable degree of short-range or...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Experimental evidence that short-range intermolecular aggregation is sufficient for efficient charge transport in conjugated polymers

Wang

Fabiano

Himmelberger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

183

206

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“…395 Both solar cell devices and FET devices were fabricated and studied. By using xylene:CN cosolvents, laterally phase-separated blends were obtained, leading to a high solar cell performance with a PCE of 1.31%.…”

Section: Naphthalene Diimide-based Polymer Acceptorsmentioning

confidence: 99%

Recent Advances in Bulk Heterojunction Polymer Solar Cells

et al. 2015

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“…45 In contrast, Fabiano et al reported that using p-xylene rather than chlorobenzene is better for the improvement of efficiency due to the formation of lateral phase segregation for P(NDI2OD-T2). 47 In a similar period, we have also concentrated on the same material system and found that the quality of the polymer:polymer BHJ films prepared using p-xylene was quite dependent on the coating conditions, owing to the relatively low solubility of polymers in the p-xylene solvent, which led to the low reproduction ratio (probability) for achieving >5% PCE.…”

Section: ■ Introductionmentioning

confidence: 96%

Pronounced Cosolvent Effects in Polymer:Polymer Bulk Heterojunction Solar Cells with Sulfur-Rich Electron-Donating and Imide-Containing Electron-Accepting Polymers

Nam

Woo

Seo

et al. 2015

ACS Appl. Mater. Interfaces

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The performance of solar cells with a polymer:polymer bulk heterojunction (BHJ) structure, consisting of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) donor and poly[[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)] (P(NDI2OD-T2)) acceptor polymers, was investigated as a function of cosolvent (p-xylene:chlorobenzene (pXL:CB)) composition ratio. A remarkable efficiency improvement (∼38%) was achieved by spin-coating the photoactive blend layer from pXL:CB = 80:20 (volume) rather than pXL alone, but the efficiency then decreased when the CB content increased further to pXL:CB = 60:40. The improved efficiency was correlated with a particular PTB7-Th:P(NDI2OD-T2) donor-acceptor blend nanostructure, evidenced by a fiber-like surface morphology, a red-shifted optical absorption, and enhanced PL quenching. Further device optimization for pXL:CB = 80:20 films yielded a power conversion efficiency of ∼5.4%. However, these devices showed very poor stability (∼15 min for a 50% reduction in initial efficiency), owing specifically to degradation of the PTB7-Th donor-component. Replacing PTB7-Th with a more stable donor polymer will be essential for any application potential to be realized.

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Charge Transport Orthogonality in All‐Polymer Blend Transistors, Diodes, and Solar Cells

Cited by 65 publications

References 54 publications

Experimental evidence that short-range intermolecular aggregation is sufficient for efficient charge transport in conjugated polymers

Experimental evidence that short-range intermolecular aggregation is sufficient for efficient charge transport in conjugated polymers

Recent Advances in Bulk Heterojunction Polymer Solar Cells

Pronounced Cosolvent Effects in Polymer:Polymer Bulk Heterojunction Solar Cells with Sulfur-Rich Electron-Donating and Imide-Containing Electron-Accepting Polymers

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