Doping of Organic Semiconductors: Impact of Dopant Strength and Electronic Coupling

Méndez, H.; Heimel, Georg; Opitz, Andreas; Sauer, Katrein; Barkowski, Patrick; Oehzelt, Martin; Soeda, Junshi; Okamoto, Toshihiro; Takeya, Jun; Arlin, Jean-Baptiste; Balandier, Jean‐Yves; Geerts, Yves; Koch, Norbert; Salzmann, Ingo

doi:10.1002/ange.201302396

Cited by 47 publications

(72 citation statements)

References 35 publications

(37 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the discrete energy levels involved in the integer charge transfer model, the hybrid charge transfer model describes the doping of organic semiconductors via the formation of charge transfer states arising from orbital mixing between donor and acceptor orbitals. 13 For a more comprehensive discussion on the hybrid charge transfer model and doping in organic semiconductors, the reader is referred to another review if required.…”

Section: Doping In Organic Semiconductorsmentioning

confidence: 99%

Review—Organic Materials for Thermoelectric Energy Generation

Cowen

Atoyo

Carnie

et al. 2017

ECS J. Solid State Sci. Technol.

129

View full text Add to dashboard Cite

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...

show abstract

Section: Doping In Organic Semiconductorsmentioning

confidence: 99%

Review—Organic Materials for Thermoelectric Energy Generation

Cowen

Atoyo

Carnie

et al. 2017

ECS J. Solid State Sci. Technol.

129

View full text Add to dashboard Cite

show abstract

“…The former can be achieved by properly preparing samples. Since optical absorption spectroscopy (UV−vis−near-IR) is commonly used to observe charge transfer between host molecules and dopants, 25,34,35 it will allow us to qualitatively observe the dopant diffusion.…”

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

View full text Add to dashboard Cite

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.

show abstract

“…Therefore, it is likely that minor molecular orbital hybridization between the HOMO of MEH-PPV and the LUMO of Alq 3 is achieved. Thus, a ground state charge-transfer complex is formed, in which occupation of the available states results in a low doping efficiency [10]. The room temperature normalized PL spectra for various concentrations of Alq 3 are depicted in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Although several organic based devices, i.e., organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs), have matured for commercial applications, still a long-standing challenge in molecular electronics relays on doping of organic semiconductors [6][7][8][9][10]. Therefore, nanoelectronic engineering by doping of semiconducting materials results from tuned molecules for well-targeted applications.…”

Section: Introductionmentioning

confidence: 99%

“…Among the key features of doping organic semiconductors are: (i) precise adjustment of the position of the Fermi level relative to the semiconductor transport levels, (ii) control of energy barriers for charge injection/extraction, and hence (iii) reduction of ohmic losses in transport layers due to increased * corresponding author; e-mail: beynor.paez@unimilitar.edu.co conductivity [10,[14][15][16][17]. In a previous work, Ahmad et al found that blending MEH-PPV with Alq 3 in chloroform leads to minor changes in the photoluminescence and favors the photodetection properties [18].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Luminescence Tuning of MEH-PPV for Organic Electronic Applications

Paez-Sierra

Marulanda

2016

Acta Phys. Pol. A

View full text Add to dashboard Cite

In this report, a doped semiconducting ink consisting of a blended poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) with aluminium-tris (8-hydroxychinolin) (Alq3) and diluted in toluene is formulated. The intentional doping with the electron transport nanoparticle Alq3 results in an additional band gap state of the hole transport MEH-PPV polymer and reduction of the switch on voltage of the organic LED display. Doping is probed at room temperature with photoluminescence spectroscopy. Photoluminescence results revealed that as the Alq3 content increases in blends, characteristic peaks of intensities of MEH-PPV are broadened and reduced. In addition, the emission for Alq3 concentrations between 30% and 60% are featured by a band at 565 nm (2.19 eV) for the lower concentration and consistently blue shifted to 530 nm (2.33 eV) for the higher concentration. This new band at 565 nm (2.19 eV) neither belongs to pure MEH-PPV nor to Alq3 and evidences charge transfer from the lowest unoccupied molecular orbital of the Alq3 to the highest occupied molecular orbital of the MEH-PPV.

show abstract

Doping of Organic Semiconductors: Impact of Dopant Strength and Electronic Coupling

Cited by 47 publications

References 35 publications

Review—Organic Materials for Thermoelectric Energy Generation

Review—Organic Materials for Thermoelectric Energy Generation

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

Luminescence Tuning of MEH-PPV for Organic Electronic Applications

Contact Info

Product

Resources

About

Doping of Organic Semiconductors: Impact of Dopant Strength and Electronic Coupling

Cited by 47 publications

References 35 publications

Review—Organic Materials for Thermoelectric Energy Generation

Review—Organic Materials for Thermoelectric Energy Generation

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

Luminescence Tuning of MEH-PPV for Organic Electronic Applications

Contact Info

Product

Resources

About

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