Impact of Interfacial Microstructure on Charge Carrier Transport in Solution‐Processed Conjugated Polymer Field‐Effect Transistors

Li, Meng Meng; An, Cunbin; Marszałek, Tomasz; Baumgarten, Martin; Müllen, Kläus; Pisula, Wojciech

doi:10.1002/adma.201503552

Cited by 60 publications

(86 citation statements)

References 39 publications

(57 reference statements)

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“…[ 10,11 ] The use of these substrate materials offers opportunities for a variety of novel applications, but they are usually characterized by a larger surface roughness than conventional substrate materials, and this can have detrimental effects on the performance of the devices. [ 12–26 ]…”

Section: Introductionmentioning

confidence: 99%

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Geiger

Acharya

Reutter

et al. 2020

Adv Materials Inter

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In organic thin‐film transistors (TFTs) fabricated in the inverted (bottom‐gate) device structure, the surface roughness of the gate dielectric onto which the organic‐semiconductor layer is deposited is expected to have a significant effect on the TFT characteristics. To quantitatively evaluate this effect, a method to tune the surface roughness of a gate dielectric consisting of a thin layer of aluminum oxide and an alkylphosphonic acid self‐assembled monolayer over a wide range by controlling a single process parameter, namely the substrate temperature during the deposition of the aluminum gate electrodes, is developed. All other process parameters remain constant in the experiments, so that any differences observed in the TFT performance can be confidently ascribed to effects related to the difference in the gate‐dielectric surface roughness. It is found that an increase in surface roughness leads to a significant decrease in the effective charge‐carrier mobility and an increase in the subthreshold swing. It is shown that a larger gate‐dielectric surface roughness leads to a larger density of grain boundaries in the semiconductor layer, which in turn produces a larger density of localized trap states in the semiconductor.

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Section: Introductionmentioning

confidence: 99%

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Geiger

Acharya

Reutter

et al. 2020

Adv Materials Inter

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“…Semiconducting polymers show potential for applications in organic field‐effect transistors (OFET) due to their advantages in lightweight, mechanical flexibility, and solution processability compared with inorganic semiconductors . Solution processing, as the only possibility for thin‐film deposition of conjugated polymers, offers opportunities to affect the charge‐carrier mobility in OFET devices, because of its fine control over the semiconductor microstructure and molecular ordering that play a critical role in the charge‐carrier transport .…”

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confidence: 99%

“…In this study, three conjugated polymers consisting of 5,6‐difluorobenzothiadiazole as the acceptor and quarterthiophene attached with long branched alkyl chains as the donor unit are investigated, which are FBT‐Th 4 (1,4)‐2DT with low and high molecular weights (LMW and HMW) and FBT‐Th 4 (1,4)‐2OD (Figure ) . Details of the synthetic procedures are described in the Supporting Information.…”

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confidence: 99%

“…In order to remove residual solvent the thin films are annealed at 100 °C for 30 min under a nitrogen atmosphere. This post‐treatment has no impact on the film morphology and molecular ordering . The topographies of the corresponding films are inspected by atomic force microscopy (AFM) in tapping mode, as shown in Figure and Figure S2 (Supporting Information).…”

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confidence: 99%

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Controlling the Surface Organization of Conjugated Donor–Acceptor Polymers by their Aggregation in Solution

Marszałek

et al. 2016

Advanced Materials

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“…(Figure 6a). [41][42] The microstructure of the dip coated thin films can be optimized by proper solvents and dip coating speeds. For instance, aligned fibers of P3 were dip coated from chloroform solution.…”

Section: Molecular Simulationsmentioning

confidence: 99%

Cyclopentadithiophene–Benzothiadiazole Donor–Acceptor Polymers as Prototypical Semiconductors for High-Performance Field-Effect Transistors

Pisula

et al. 2018

Acc. Chem. Res.

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106

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Donor-acceptor (D-A) conjugated polymers are of great interest as organic semiconductors, because they offer a rational tailoring of the electronic properties by modification of the donor and acceptor units. Nowadays, D-A polymers exhibit field-effect mobilities on the order of 10-10 cm V s, while several examples showed a mobility over 10 cm V s. The development of cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers one decade ago represents an important step toward high-performance organic semiconductors for field-effect transistors. The significant rise in field-effect mobility of CDT-BTZ in comparison to the existing D-A polymers at that time opened the door to a new research field with a large number of novel D-A systems. From this point, the device performance of CDT-BTZ was gradually improved by a systematic optimization of the synthesis and polymer structure as well as by an efficient solution processing into long-range ordered thin films. The key aspect was a comprehensive understanding of the relation between polymer structure and solid-state organization. Due to their fundamental role for the field of D-A polymers in general, this Account will for the first time explicitly focus on prototypical CDT-BTZ polymers, while other reviews provide an excellent general overview on D-A polymers. The first part of this Account discusses strategies for improving the charge carrier transport, focusing on chemical aspects. Improved synthesis as an essential stage toward high purity, and high molecular weight is a prerequisite for molecular order. The modification of substituents is a further crucial feature to tune the CDT-BTZ packing and self-assembly. Linear alkyl side chains facilitate intermolecular π-stacking interactions, while branched ones increase solubility and alter the polymer packing. Additional control over the supramolecular organization of CDT-BTZ polymers is introduced by alkenyl substituents via their cis-trans isomerization. The last discussed chemical concept is based on heteroatom variation within the CDT unit. The relationships found experimentally for CDT-BTZ between polymer chemical structure, solid-state organization, and charge carrier transport are explained by means of theoretical simulations. Besides the effects of molecular design, the second part of this Account discusses the processing conditions from solution. The film microstructure, defined as a mesoscopic domain organization, is critically affected by solution processing. Suitable processing techniques allow the formation of a long-range order and a uniaxial orientation of the CDT-BTZ chains, thus lowering the trapping density of grain boundaries for charge carriers. For instance, alignment of the CDT-BTZ polymer by dip-coating yields films with a pronounced structural and electrical anisotropy and favors a fast migration of charge carriers along the conjugated backbones in the deposition direction. By using film compression with the assistance of an ionic liquid, one even obtains CDT-BTZ films with a band-like transport a...

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Impact of Interfacial Microstructure on Charge Carrier Transport in Solution‐Processed Conjugated Polymer Field‐Effect Transistors

Cited by 60 publications

References 39 publications

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Controlling the Surface Organization of Conjugated Donor–Acceptor Polymers by their Aggregation in Solution

Cyclopentadithiophene–Benzothiadiazole Donor–Acceptor Polymers as Prototypical Semiconductors for High-Performance Field-Effect Transistors

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