Exciton Binding Energies in Conjugated Polyelectrolyte Films

Seo, Jung Hwa; Jin, Youngeup; Brzeziński, Jacek Z.; Walker, Bright; Nguyen, Thuc‐Quyen

doi:10.1002/cphc.200800751

Cited by 34 publications

(30 citation statements)

References 43 publications

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“…[10] For polyelectrolytes with the same backbone but different counter ions, different ionization potentials (IPs) and electron affinities were reported by Nguyen and co-workers using ultraviolet photoelectron spectroscopy (UPS) studies. [11,12] Many of the reported CPEs were synthesized by oxidative methods in a noncontrolled fashion. However, with poly(6-(thiophen-3-yl)hexane-1-sulfonate) tetrabutylammonium, we have recently reported a well-defined CPE exhibiting a high bulk charge transport mobility, which led to OECTs operating in accumulation mode with high transconductance.…”

Section: Doi: 101002/macp201700374mentioning

confidence: 99%

“…Typically, high degree of π‐stacking of the backbones is favorable for a lot of applications, since the charge transport mobility increases with the degree of aggregation/crystallization of the polymer chains . For polyelectrolytes with the same backbone but different counter ions, different ionization potentials (IPs) and electron affinities were reported by Nguyen and co‐workers using ultraviolet photoelectron spectroscopy (UPS) studies …”

Section: Introductionmentioning

confidence: 99%

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Smaller Counter Cation for Higher Transconductance in Anionic Conjugated Polyelectrolytes

Schmidt

ElMahmoudy

Malliaras

et al. 2017

Macro Chemistry & Physics

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Conjugated polyelectrolytes (CPEs) are a focus of research because combine their inherent electrical conductivity and the ability to interact with ions in aqueous solutions or biological systems. However, it is still not understood to what degree the counter ion in CPEs influences the properties of the CPE itself and the performance of electronic transducers. In order to investigate this, three different conjugated polyelectrolytes, poly(6‐(thiophen‐3‐yl)hexane‐1‐sulfonate)s (PTHS−X+), are synthesized, which have the same polythiophene backbone but different X+ counter ions: the bulky tetrabutylammonium (TBA+), tetraethylammonium (TEA+), and the smallest tetramethylammonium (TMA+). At the interface with biological systems, thin CPE films have to be stable in an aqueous environment and should allow the inward and outward flow of ions from the electrolyte. Since the studied PTHS−X+ have different solubilities in water, the optical properties of pristine PTHS−X+ as well as of crosslinked PTHS−X+ via UV–vis absorption spectroscopy are investigated additionally. PTHS−TMA+ exhibits better aggregation, fast interdiffusion of ions, and fast recovery from the oxidized state. Additionally, spectroelectrochemical and cyclic voltammetric as well as electrochemical capacitance investigations show that PTHS−TMA+ can be oxidized to a higher degree. This leads to a better performance of PTHS−TMA+‐based organic electrochemical transistors.

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Section: Doi: 101002/macp201700374mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Smaller Counter Cation for Higher Transconductance in Anionic Conjugated Polyelectrolytes

Schmidt

ElMahmoudy

Malliaras

et al. 2017

Macro Chemistry & Physics

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“…41 From Equation (11) we observe that the exciton binding energy is dependent on transport gap and optical energy. 41 From Equation (11) we observe that the exciton binding energy is dependent on transport gap and optical energy.…”

Section: Moleculesmentioning

confidence: 99%

Computational study on thermally activated delayed fluorescence of donor–linker–acceptor network molecules

2016

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We have investigated the structure property relationship of organic molecules with Donor-Linker-Acceptor (DLA) framework which can be used as precursors of OLED materials employing Density Functional Theory (DFT) and Time dependent DFT calculations. Two types of linkers' thiophene (π-conjugated) and ethylene (non-π-conjugated), carbazole as electron donor and cyano-substituted benzene as electron acceptor in DLA framework are chosen. Donor-Linker-Acceptor network allows the HOMO and LUMO orbitals to be spatially separated reducing the overlap of frontier orbitals decreasing the exchange energy (J) which results in smaller ΔEST (energy gap between excited singlet and triplet states) thus allowing us to realize metal free molecules suitable for OLED applications. Incorporation of donor and acceptor groups in the same moiety helps in reducing the number of layers conventionally used in OLEDS, reducing the cost with more simplified device fabrication. By enhancing the electron donating nature of donor group and increasing the withdrawing nature of acceptor group we observe a decrease in exchange energy, which is further decreased by a non-conjugated linker. Important properties like change in dipole moments, absorption and emission energies corresponding oscillator strengths, transport energy gaps, electron affinities, ionization potentials (vertical and adiabatic), reorganization energies, and exciton binding energies of various substituted molecules are investigated and their role in determining the efficiencies are discussed. In order to account the effects of solvents and their role in altering various properties, the studies are carried out in polar and non-polar solvent phases in addition to the gas phase calculations. Please do not adjust marginsPlease do not adjust margins towards HOMO are found to be 89%, 9% and 2% and for LUMO 2%, 35% and 63% respectively. For 2.a, the contribution of donor, linker and acceptor towards HOMO are found to be 95%, 4% and 1% and for LUMO 1%, 4% and 95% respectively. Figure 3. HOMO, LUMO orbitals of molecules with thiophene linker (1.a-1.e) and ethylene linker (2.a-2.e). Grey, white, blue, red and yellow colours indicate carbon, hydrogen, nitrogen, oxygen and sulphur atoms respectively. Graphical AbstractWe have investigated the structure property relationship of organic molecules with Donor-Linker-Acceptor (DLA) framework which can be used as precursors of OLED materials employing Density Functional Theory (DFT). Two types of linkers thiophene (π-conjugated) and ethylene (non-πconjugated), carbazole as electron donor and cyano-substituted benzene as electron acceptor in DLA framework are chosen. By enhancing the electron donating nature of donor group and increasing the withdrawing nature of acceptor group we observe a decrease in exchange energy, which is further decreased by a non-conjugated linker. Important properties like energy gap between excited singlet and triplet states, change in dipole moments, absorption and emission energies corresponding oscillator strengths, tra...

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“…The LUMO energy levels were estimated from the equation [24], E LUMO =E HOMO +E g,TD . A similar strategy has been used in the experiments (E LUMO =E HOMO +E opt ) [15]. There are no imaginary frequencies for all monomers and dimers at the present theoretical level.…”

Section: Computational Detailsmentioning

confidence: 83%

“…Computationally driven material design has attracted increasing interest [9,14], many quantum mechanical simulations on the polymer systems have focused on the influence of substituent on the performance of polymer solar cells, including TPD-based push-pull conjugated polymers [15][16][17][18]. However, a study of electron-withdrawing group on nitrogen atom with little steric hindrance between neighboring aromatic repeat units in BDT-TPD-based copolymers appears to be lacking, which can be a useful method for enhancing intramolecular electron transfer in donor-acceptor conjugated polymers.…”

Section: Introductionmentioning

confidence: 99%

Computational study on the effects of substituent and heteroatom on physical properties and solar cell performance in donor-acceptor conjugated polymers based on benzodithiophene

Zhang

Shen

et al. 2014

J Mol Model

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Computationally driven material design has attracted increasing interest to accelerate the search for optimal conjugated donor materials in bulk heterojunction organic solar cells. A series of novel copolymers containing benzo[1,2-b:4,5-b']dithiophene (BDT) and thieno[3,4-c]pyrrole-4,6-dione (TPD) derivatives were simulated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). We performed a systematic study on the influences on molecular geometry parameters, electronic properties, optical properties, photovoltaic performances, and intermolecular stacking as well as hole mobility when different chalcogenophenes in TPD derivatives were used and functional groups with different electron-withdrawing abilities such as alkyl, fluorine, sufonyl, and cyano were introduced to the nitrogen positions in electron-deficient units. The substitution position of electron-withdrawing groups may cause little steric hindrance to the neighboring donor units, especially fluorine and cyano group. It was found that the incorporation of these new electron-deficient substituents and sulfur-selenium exchange can be applicable to further modify and optimize existing molecular structures. Our findings will provide valuable guidance and chemical methodologies for a judicious material design of conjugated polymers for solar cell applications with desirable photovoltaic characteristics.

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Exciton Binding Energies in Conjugated Polyelectrolyte Films

Cited by 34 publications

References 43 publications

Smaller Counter Cation for Higher Transconductance in Anionic Conjugated Polyelectrolytes

Smaller Counter Cation for Higher Transconductance in Anionic Conjugated Polyelectrolytes

Computational study on thermally activated delayed fluorescence of donor–linker–acceptor network molecules

Computational study on the effects of substituent and heteroatom on physical properties and solar cell performance in donor-acceptor conjugated polymers based on benzodithiophene

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