Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

Wang, Chenchen; Duong, Duc T.; Vandewal, Koen; Rivnay, Jonathan; Salleo, Alberto

doi:10.1103/physrevb.91.085205

Cited by 118 publications

(192 citation statements)

References 40 publications

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“…Importantly, this mobility is directly comparable with the one from the simulations discussed above. In the case of integer CT with (nearly) unity efficiency, as has been observed for the P3HT:F 4 TCNQ system [8,17,27], this is the actual mobility averaged over all charge carriers.…”

Section: E Experimentsmentioning

confidence: 67%

“…with ν 0 as the attempt-to-hop frequency and n as the charge carrier density that is set equal to the doping concentration N d −, i.e., full integer charge transfer (CT) is assumed [8,17,27]. For both the analytical models and MC, mobilities are calculated from conductivities by dividing by the dopant concentration, giving the mean mobility for all available charges.…”

Section: A Model Descriptionmentioning

confidence: 99%

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Impact of doping on the density of states and the mobility in organic semiconductors

2016

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We experimentally investigated conductivity and mobility of poly(3-hexylthiophene) (P3HT) doped with tetrafluorotetracyanoquinodimethane (F 4 TCNQ) for various relative doping concentrations ranging from ultralow (10 −5 ) to high (10 −1 ) and various active layer thicknesses. Although the measured conductivity monotonously increases with increasing doping concentration, the mobilities decrease, in agreement with previously published work. Additionally, we developed a simple yet quantitative model to rationalize the results on basis of a modification of the density of states (DOS) by the Coulomb potentials of ionized dopants. The DOS was integrated in a three-dimensional (3D) hopping formalism in which parameters such as energetic disorder, intersite distance, energy level difference, and temperature were varied. We compared predictions of our model as well as those of a previously developed model to kinetic Monte Carlo (MC) modeling and found that only the former model accurately reproduces the mobility of MC modeling in a large part of the parameter space. Importantly, both our model and MC simulations are in good agreement with experiments; the crucial ingredient to both is the formation of a deep trap tail in the Gaussian DOS with increasing doping concentration.

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Section: E Experimentsmentioning

confidence: 67%

Section: A Model Descriptionmentioning

confidence: 99%

Impact of doping on the density of states and the mobility in organic semiconductors

2016

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“…Finally, P3BT decomposed slowly from ≈320 °C onward (because of the degradation of lighter fragments such as CS units) and rapidly from ≈430 °C onward (because of the degradation of both the backbone and the side chain, sulfur oxidation, etc.) . The weight loss profile of the SIS/P3BT/BCF composite was obviously the sum of those of the three constituent materials, indicating that the composite was a blended mixture of SIS, P3BT, and BCF, as illustrated in Figure d.…”

Section: Resultsmentioning

confidence: 93%

“…It should be noted that the neat BCF peak was not overlapped with any of the peaks in Figure b (Figure S2, Supporting Information). Given that two polaron peaks and a bipolaron peak of poly(3‐hexylthiophene) were positioned at 775.6, 867.8, and 761.35 nm, respectively, the broad absorption band from ≈750 to ≈1000 nm might have resulted from the formation of polarons and bipolarons in P3BT. However, it was difficult to clearly deconvolute the absorption band because the polaron and bipolaron peaks overlapped with the spectral features owing to the formation of a Lewis acid–base complex, water‐reactive adduct ((C 6 F 5 ) 3 B(OH 2 )), and other BCF‐related products .…”

Section: Resultsmentioning

confidence: 99%

Self‐Healable and Stretchable Organic Thermoelectric Materials: Electrically Percolated Polymer Nanowires Embedded in Thermoplastic Elastomer Matrix

Jeong

Jung

Suh

et al. 2019

Adv Funct Materials

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Self‐healable and stretchable energy‐harvesting materials can provide a new avenue for the realization of self‐powered wearable electronics, including electronic skins, whose main materials are required to be robust to and stable under external damage and severe mechanical stresses. However, thermoelectric (TE) materials showing both self‐healing properties and stretchability have not yet been demonstrated despite their great potential to harvest thermal energy in the human body. As most existing TE materials are either mechanically brittle or unrecoverable after being subjected to damage, a novel approach is necessary for designing such materials. Herein, self‐healable and stretchable TE materials based on all‐organic composite system wherein polymer semiconductor nanowires are p‐doped with a molecular dopant and embedded in a thermoplastic elastomer matrix are reported. The polymer nanowires are electrically percolated in the matrix, and the resulting composite materials exhibit good TE performance. The composites also exhibit both excellent self‐healing properties under mild heat and pressure conditions and good stretchability. It is believed that this work can be a cornerstone for the design of self‐healable and stretchable energy‐harvesting materials as it provides useful guidelines for imparting electrical conductivity to insulating thermoplastic elastomers, which typically possess versatile and useful mechanical properties.

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“…9−19 In P3HT:F4TCNQ, for reasons not yet fully understood, only about 5% of the holes injected by dopants actively contribute to charge transport 9 (that is, p free ≪ p bound ), even though nearly all F4TCNQ molecules in the film are fully ionized. 15 Therefore, relevant doping levels in OSCs are much higher, ranging from ppt to well over 100 wt % in commercial formulations of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)polystyrenesulfonate), another widely used polymer:dopant blend. Clearly, with such high doping levels required, compensation doping is not a feasible approach to fabricating homojunctions in organic semiconductors.…”

Section: ■ Introductionmentioning

confidence: 99%

Quantitative Dedoping of Conductive Polymers

Jacobs¹,

Wang²,

Hafezi³

et al. 2017

Chem. Mater.

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Although doping is a cornerstone of the inorganic semiconductor industry, most devices using organic semiconductors (OSCs) make use of intrinsic (undoped) materials. Recent work on OSC doping has focused on the use of dopants to modify a material’s physical properties, such as solubility, in addition to electronic and optical properties. However, if these effects are to be exploited in device manufacturing, a method for dedoping organic semiconductors is required. Here, we outline two chemical strategies for dedoping OSC films. In the first strategy, we use an electron donor (a tertiary amine) to act as competitive donor. This process is based on a thermodynamic equilibrium between ionization of the donor and OSC and results in only partial dedoping. In the second strategy, we use an electron donor that subsequently reacts with the p-type dopant to create a nondoping product molecule. Primary and secondary amines undergo a rapid addition reaction with the dopant molecule 2,3,5,6-tetrafluoro-7,7,8,8,-tetracyanoquinodimethane (F4TCNQ), with primary amines undergoing a further reaction eliminating HCN. Under optimized conditions, films of semiconducting polymer poly(3-hexylthiophene) (P3HT) dedoped with 1-propylamine (PA) reach as-cast fluorescence intensities within 5 s of exposure to the amine, eventually reaching 140% of the as-cast values. Field-effect mobilities similarly recover after dedoping. Quantitative fluorescence recovery is possible even in highly fluorescent polymers such as PFB, which are expected to be much more sensitive to residual dopants. Interestingly, treatment of undoped films with PA also yields increased fluorescence intensity and a reduction in conductivity of at least 2 orders of magnitude. These results indicate that the process quantitatively removes not only F4TCNQ but also intrinsic p-type impurities present in as-cast films. The dedoping strategies outlined in this article are generally applicable to other p- and n-type molecular dopants in OSC films.

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Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

Cited by 118 publications

References 40 publications

Impact of doping on the density of states and the mobility in organic semiconductors

Impact of doping on the density of states and the mobility in organic semiconductors

Self‐Healable and Stretchable Organic Thermoelectric Materials: Electrically Percolated Polymer Nanowires Embedded in Thermoplastic Elastomer Matrix

Quantitative Dedoping of Conductive Polymers

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