n-type charge transport in heavily p-doped polymers

Liang, Zhiming; Choi, Hyun Ho; Luo, Xuyi; Liu, Tuo; Abtahi, Ashkan; Ramasamy, Uma Shantini; Hitron, John Andrew; Baustert, Kyle N.; Hempel, Jacob; Boehm, Alex; Ansary, Armin; Strachan, Douglas R.; Mei, Jianguo; Risko, Chad; Podzorov, Vitaly; Graham, Kenneth R.

doi:10.1038/s41563-020-00859-3

Cited by 86 publications

(103 citation statements)

References 56 publications

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“…The highest a was measured at 5 mol% N-DMBI, at higher dopant concentrations this value decreases rapidly, as increased dopant concentrations reduce the average energy of the charge carriers, also known as transport energy (E t ). 42 a shows negligible dependency on the temperature. The highest power factor for P1G was also achieved at this doping concentration (0.077 mW K À2 m À1 at room temperature and 0.25 mW K À2 m À1 at 130 1C).…”

Section: Resultsmentioning

confidence: 90%

Backbone-driven host–dopant miscibility modulates molecular doping in NDI conjugated polymers

et al. 2022

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Section: Resultsmentioning

confidence: 90%

Backbone-driven host–dopant miscibility modulates molecular doping in NDI conjugated polymers

et al. 2022

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“…In all materials the occupied states extend to the Fermi energy, as is typical for heavily p-doped CPs. 46 However, the work function increases from 4.88 eV for rr-P3HT with BF 4 À to 5.60 eV with B(Ph[CF 3 ] 2 ) 4 À . In parallel with the CV results, the IEs for rr-and rra-P3HT with B(Ph[CF 3 ] 2 ) 4 À are similar at 5.55 and 5.60 eV, respectively, yet the IEs differ by 0.50 eV for rr-and rra-P3HT when BF 4 À serves as the counterion.…”

Section: Resultsmentioning

confidence: 99%

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

Baustert

Abtahi

Ayyash

et al. 2021

Journal of Polymer Science

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Chemical and electrochemical doping of π-conjugated polymers is an important aspect in determining the performance and enabling the operation of many organic electronic devices, from organic light emitting diodes and thermoelectrics to organic electrochemical transistors. In both chemical doping and electrochemical doping an ionized dopant or counterion is present along with the doped π-conjugated polymer. This dopant or counterion is not a benign spectator, rather, its presence can significantly impact the optical, electronic, and thermoelectric properties of the resulting material. Here, we investigate how counterion structure impacts the electrochemical doping ability, oxidation potential, ionization energy, and polaron absorbance of regioregular (rr) and regiorandom (rra) P3HT. We find that in most cases the anion has a small effect on the polymer oxidation potential, except for in the case of rr-P3HT with the large tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion. We propose that this large anion is excluded from the crystalline regions and thus the oxidation potential is similar to that of rra-P3HT. The anions also result in significant differences in polaron absorbance and ionization energies, thereby emphasizing the important role of the counterion in determining the optical and electronic properties of doped π-conjugated polymers.

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“…Specifically, our study indicates preferential doping of the crystalline regions through weaker dopants is needed to achieve high PF in P3MEET. A recent study by Liang et al have demonstrated how to control the sign of α by balancing charge carrier concentration and charge‐carrier mobilities in the crystalline and amorphous regions of a doped CP film 59 . Therefore, going forward, strategies towards proper CP and dopant pairing need to consider the doping level between the crystalline and amorphous regions to balance the correlation between α and σ , and the ultimate PF .…”

Section: Resultsmentioning

confidence: 99%

Correlating conductivity and Seebeck coefficient to doping within crystalline and amorphous domains in poly(3‐(methoxyethoxyethoxy)thiophene)

Dong

Onorato

et al. 2021

Journal of Polymer Science

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Molecular doping of conjugated polymers (CPs) plays a vital role in optimizing organic electronic and energy applications. For the case of organic thermoelectrics, it is commonly believed that doping CPs with a strong dopant could result in higher conductivity (σ) and thus better power factor (PF). Herein, by investigating thermoelectric performance of a polar side‐chain bearing CP, poly(3‐(methoxyethoxyethoxy)thiophene) (P3MEET), vapor doped with fluorinated‐derivative of tetracyanoquinodimethane FnTCNQ (n = 1, 2, 4), we show that using strong dopants can in fact have detrimental effects on the thermoelectric performance of CPs. Despite possessing higher electron affinity, doping P3MEET with F4TCNQ only results in a σ (27.0 S/cm) comparable to samples doped with other two weaker dopants F2TCNQ and F1TCNQ (26.4 and 20.1 S/cm). Interestingly, F4TCNQ‐doped samples display a marked reduction in the Seebeck coefficient (α) compared to F1TCNQ‐ and F2TCNQ‐doped samples from 42 to 13 μV/K, leading to an undesirable suppression of the PF. Structural characterizations coupled with Kang‐Snyder modeling of the α–σ relation show that the reduction of α in F4TCNQ‐doped P3MEET samples originates from the generation of low mobility carrier within P3MEET's amorphous domain. Our results demonstrate that factors such as dopant distribution and doping efficiency within the crystalline and amorphous domains of CPs should play a crucial role in advancing rational design for organic thermoelectrics.

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n-type charge transport in heavily p-doped polymers

Cited by 86 publications

References 56 publications

Backbone-driven host–dopant miscibility modulates molecular doping in NDI conjugated polymers

Backbone-driven host–dopant miscibility modulates molecular doping in NDI conjugated polymers

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

Correlating conductivity and Seebeck coefficient to doping within crystalline and amorphous domains in poly(3‐(methoxyethoxyethoxy)thiophene)

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