Drastic Control of Texture in a High Performance n-Type Polymeric Semiconductor and Implications for Charge Transport

Rivnay, Jonathan; Steyrleuthner, Robert; Jimison, Leslie H.; Casadei, Alberto; Chen, Zhihua; Toney, Michael F.; Facchetti, Antonio; Neher, Dieter; Salleo, Alberto

doi:10.1021/ma200864s

Cited by 288 publications

(454 citation statements)

References 38 publications

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“…Mobility measured by the SCLC method is more relevant to the bulk process, e.g., organic photovoltaic device and OLED (organic light-emitting device) devices. 48,49 All donor:acceptor polymer blend film devices were made similarly as the all-PSCs devices. The electron-only device was fabricated using ITO/ZnO/active layer/Al structure, and hole-only device was fabricated using ITO/MoOx/active layer/Au structure (the detailed procedure of device fabrication is given in the Experimental Section).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Improved All-Polymer Solar Cell Performance of n-Type Naphthalene Diimide–Bithiophene P(NDI2OD-T2) Copolymer by Incorporation of Perylene Diimide as Coacceptor

et al. 2016

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Naphthalene diimide−bithiophene P(NDI2OD-T2) is a well-known donor−acceptor polymer, previously explored as n-type material in all-polymer solar cells (all-PSCs) and organic field effect transistor (OFETs) applications. The optical, bulk, electrochemical, and semiconducting properties of P(NDI2OD-T2) polymer were tuned via random incorporation of perylene diimide (PDI) as coacceptor with naphthalene diimide (NDI). Three random copolymers containing 2,2′-bithiophene as donor unit and varying compositions of naphthalene diimide (NDI) and perylene diimide (xPDI, x = 15, 30, and 50 mol % of PDI) as two mixed acceptors were synthesized by Stille coupling copolymerization. Proton NMR spectra recorded in CDCl 3 showed that the π−π stacking induced aggregation among the naphthalene units could be successfully disrupted by the random incorporation of bulky PDI units. The newly synthesized random copolymers were investigated as electron acceptors in BHJ all-PSCs, and their performance was compared with P(NDI2OD-T2) as reference polymer. An enhanced PCE of 5.03% was observed for BHJ all-PSCs (all-polymer solar cells) fabricated using NDI-Th-PDI30 as acceptor and PTB7-Th as donor, while the reference polymer blend with the same donor polymer exhibited PCE of 2.97% efficiency under similar conditions. SCLC bulk carrier mobility measured for blend devices showed improved charge mobility compared to reference polymer, with PTB7-Th:NDI-Th-PDI30 blend device exhibiting the high hole and electron mobility of 4.2 × 10 −4 and 1.5 × 10 −4 cm 2 /(V s), respectively. This work demonstrates the importance of molecular design via random copolymer strategy to control the bulk crystallinity, compatibility, blend morphology, and solar cell performance of n-type copolymers.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Improved All-Polymer Solar Cell Performance of n-Type Naphthalene Diimide–Bithiophene P(NDI2OD-T2) Copolymer by Incorporation of Perylene Diimide as Coacceptor

et al. 2016

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“…[ 21 ] Two-dimensional grazing incidence X-ray diffraction (2D GIXD) patterns of the fi lms revealed that the mildly annealed fi lm and the meltannealed fi lm displayed quite different molecular orientations (Figure 1 b). Specifi cally, the mildly annealed P(NDI2OD-T2) fi lm showed a predominantly face-on structure (Face-on P(NDI2OD-T2)), whereas the melt-annealed fi lm exhibited an edge-on structure (Edge-on P(NDI2OD-T2)).…”

Section: Resultsmentioning

confidence: 99%

Molecular Orientation‐Dependent Bias Stress Stability in Bottom‐Gate Organic Transistors Based on an n‐Type Semiconducting Polymer

Kang

Moon

Choi

et al. 2016

Adv Elect Materials

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Despite remarkable advances in the performances of organic field‐effect transistors (OFETs) in recent years, the bias stability of OFET devices remains a critical obstacle to their commercial use. The microstructural origins of charge traps inside OFET devices are not yet clearly understood, and investigating these origins presents an important challenge. The unique electrical properties of an n‐type semiconducting polymer, 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)), are explored here to study the correlation between the microstructures of polymer semiconductor thin films and the bias stability of an OFET. It is demonstrated that although the charge carrier mobilities in a series of devices may be similar, the bias stress stabilities can differ significantly, depending on the molecular orientations of the semiconducting thin films. A higher degree of bias stress stability is attained in the P(NDI2OD‐T2) FETs prepared with face‐on thin‐film structures compared to the bias stress stability attained in the edge‐on film structures. Further experimental evidence suggests that the aliphatic alkyl chains in edge‐on‐oriented P(NDI2OD‐T2) films present a hurdle to vertical charge transport and induce large numbers of bipolarons during bias stress, in contrast with the face‐on structured thin films.

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“…This particular morphology allows good electron transport in both organic diodes and field-effect transistors (OFETs), with high in-plane mobilities of ∼0.1-0.6 cm 2 ·V -1 ·s -1 even in the presence of a substantial degree of disorder (11). However, film morphologies with predominantly edge-on oriented polymer chains were observed to yield lower performance in both diodes and top-gated OFETs because of the reduced out-of-plane mobility and larger injection barrier (16)(17)(18)(19). 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).…”

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.

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206

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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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Drastic Control of Texture in a High Performance n-Type Polymeric Semiconductor and Implications for Charge Transport

Cited by 288 publications

References 38 publications

Improved All-Polymer Solar Cell Performance of n-Type Naphthalene Diimide–Bithiophene P(NDI2OD-T2) Copolymer by Incorporation of Perylene Diimide as Coacceptor

Improved All-Polymer Solar Cell Performance of n-Type Naphthalene Diimide–Bithiophene P(NDI2OD-T2) Copolymer by Incorporation of Perylene Diimide as Coacceptor

Molecular Orientation‐Dependent Bias Stress Stability in Bottom‐Gate Organic Transistors Based on an n‐Type Semiconducting Polymer

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

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