Mechanistic Study on the Solution-Phase n-Doping of 1,3-Dimethyl-2-aryl-2,3-dihydro-1<i>H</i>-benzoimidazole Derivatives

Naab, Benjamin D.; Guo, Song; Olthof, Selina; Evans, Eric G. B.; Wei, Peng; Millhauser, Glenn L.; Kahn, Antoine; Barlow, Stephen; Marder, Seth R.; Bao, Zhenan

doi:10.1021/ja403906d

Cited by 221 publications

(295 citation statements)

References 37 publications

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“…13,26 Mechanistic studies in the solution phase found that the dopant reacted with the fullerene derivative through hydride or hydrogen atom transfer to afford host radical anions, which were responsible for the doping effect. 27 Comparative studies of the doping efficiency of fullerene-based OSCs with the same dopant in OTFTs also found a significant enhancement in device performance. 28 However, conjugated polymers, as the major class of solution-processable OSCs, are rarely n-doped in devices, especially OTFTs, 14,20,24,29 despite the significant improvement it can have on device parameters, e.g., charge carrier mobility, threshold voltage, channel current on/off ratio and contact resistance.…”

Section: Introductionmentioning

confidence: 94%

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

et al. 2018

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Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

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Section: Introductionmentioning

confidence: 94%

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

et al. 2018

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“…Through structural optimization they achieve electrical conductivities and thermoelectric power factors as high as 0.5 S.cm −1 and 1.4 μW.m −1 K −2 , respectively. A variety of new organometallic complexes, 87 hydride donors, 1,3-Dimethyl-2-phenyl-2,3-dihydro-1H-benzoimidazole (DMBI), 88 and…”

Section: N-type Organic Thermoelectric Materialsmentioning

confidence: 99%

Review—Organic Materials for Thermoelectric Energy Generation

Cowen

Atoyo

Carnie

et al. 2017

ECS J. Solid State Sci. Technol.

130

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Organic semiconductor materials have been promising alternatives to their inorganic counterparts in several electronic applications such as solar cells, light emitting diodes, field effect transistors as well as thermoelectric generators. Their low cost, light weight and flexibility make them appealing in future applications such as foldable electronics and wearable circuits using printing techniques. In this report, we present a mini-review on the organic materials that have been used for thermoelectric energy generation. The reduction in the effects of climate change, caused by the burning of fossil fuels, has recently been given increased emphasis by major world governments and it is therefore necessary to consider the efficiency of the methods we currently use to generate energy. It has previously been estimated that 63% of global energy consumption is wasted with the major form of this waste being heat.1,2 It is therefore important to develop methods of reconverting this wasted heat back in to useful forms of energy, such as electricity.Thermoelectric generators (TEG) are a promising technology which make use of a process known as the Seebeck effect for heat recovery. The Seebeck effect can be described as two dissimilar conductors or semiconductors connected thermally in parallel and electrically in series and exposed to a temperature gradient causing a difference in voltage between the two materials.3,4 In a TEG one p-type and one ntype semiconductor make use of the Seebeck effect by connecting one to the other electrically in series and thermally in parallel; a general device setup is shown in Figure 1. By connecting the two components, by a junction which is heated, the n-type component of the device transports electrons from the hot junction to a heat sink while the p-type material transports positively charged holes along the same direction of the temperature gradient. The reverse is also possible if the holes and electrons flow away from a cold connecting junction to a heated point at the end of each semiconductor, this induces a constant cooling at the junction through the Peltier effect. 4,5The quantification of the Seebeck effect, in a specific material, is given by the Seebeck coefficient, α, and is the open circuit voltage of a material subjected to a temperature gradient, commonly with units on the scale of μVK −1 to mVK −1 . 6 A materials overall efficiency in the conversion of heat to electricity is given by the dimensionless figure of merit, ZT, defined as,where σ is the electrical conductivity and κ is the thermal conductivity. [6][7][8] It is therefore necessary for thermoelectric materials to have a high electrical conductivity and a low thermal conductivity making electrically conducting metals inappropriate for thermoelectric applications due to their high thermal conductivities and low z E-mail: m.j.carnie@swansea.ac.uk; derya.baran@kaust.edu.sa; b.c.schroeder@qmul .ac.uk Seebeck coefficients. The ideal thermoelectric materials should be an electrical crystal to maximize σ and at the s...

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“…11−16 The doping mechanism occurs by an electron transfer process between the dopant molecule and the host material. 11,17 For p-type doping, the electron is transferred from the host material to the dopant, and for n-type doping the electron transfers from the dopant molecule to the host material. An important difference between doping inorganic semiconductors and doping organic electronic materials is that, for organic doping, the dopant molecules are not bound to their host material by strong covalent bonds.…”

Section: ■ Introductionmentioning

confidence: 99%

Measurement of Small Molecular Dopant F4TCNQ and C₆₀F₃₆ Diffusion in Organic Bilayer Architectures

Rochester

Jacobs

et al. 2015

ACS Appl. Mater. Interfaces

127

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The diffusion of molecules through and between organic layers is a serious stability concern in organic electronic devices. In this work, the temperature-dependent diffusion of molecular dopants through small molecule hole transport layers is observed. Specifically we investigate bilayer stacks of small molecules used for hole transport (MeO-TPD) and p-type dopants (F4TCNQ and C 60 F 36 ) used in hole injection layers for organic light emitting diodes and hole collection electrodes for organic photovoltaics. With the use of absorbance spectroscopy, photoluminescence spectroscopy, neutron reflectometry, and near-edge X-ray absorption fine structure spectroscopy, we are able to obtain a comprehensive picture of the diffusion of fluorinated small molecules through MeO-TPD layers. F4TCNQ spontaneously diffuses into the MeO-TPD material even at room temperature, while C 60 F 36 , a much bulkier molecule, is shown to have a substantially higher morphological stability. This study highlights that the differences in size/geometry and thermal properties of small molecular dopants can have a significant impact on their diffusion in organic device architectures.

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Mechanistic Study on the Solution-Phase n-Doping of 1,3-Dimethyl-2-aryl-2,3-dihydro-1H-benzoimidazole Derivatives

Cited by 221 publications

References 37 publications

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

Review—Organic Materials for Thermoelectric Energy Generation

Measurement of Small Molecular Dopant F4TCNQ and C₆₀F₃₆ Diffusion in Organic Bilayer Architectures

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Mechanistic Study on the Solution-Phase n-Doping of 1,3-Dimethyl-2-aryl-2,3-dihydro-1H-benzoimidazole Derivatives

Cited by 221 publications

References 37 publications

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

Review—Organic Materials for Thermoelectric Energy Generation

Measurement of Small Molecular Dopant F4TCNQ and C60F36 Diffusion in Organic Bilayer Architectures

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Measurement of Small Molecular Dopant F4TCNQ and C₆₀F₃₆ Diffusion in Organic Bilayer Architectures