Ultrafast Dephasing of Photoexcited Polarons in Primary Doped Polyaniline

Kim, Jeongho; Unterreiner, Andreas‐Neil; Rane, Sachin; Park, Sungnam; Jureller, Justin E.; Book, Lewis D.; Liau, Yish-Hann; Scherer, Norbert F.

doi:10.1007/978-3-642-59319-2_159

Cited by 3 publications

(7 citation statements)

References 6 publications

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“…The form of this stabilization energy is thus similar to that found for the linear vibronic coupling of a d 9 impurity in octahedral symmetry with both the symmetric a 1g and the e g Jahn−Teller mode. 7,43 A similar situation takes place for excited T states of Cr 3+ and Mn 2+ impurities under octahedral coordination. 44−48 We note that while the transition state solution always exists, the localized one, characterized by eq 4, is present only when…”

Section: Origin Of the Hopping Barriers: Simplementioning

confidence: 72%

“…TS loc 2 trap 2 trap (7) In eq 7, the last two terms are positive (E trap is negative); thus, they contribute to make the barrier, B, larger. By contrast, the first one, depending linearly on γ < 0, is negative, thus acting to reduce B.…”

Section: T H Imentioning

confidence: 99%

“…Nevertheless, this task is not simple because it requires the use of large supercells as well as an accurate treatment of electron correlation to account for the delicate balance of energies (particularly electron selfinteraction) leading to localization of the charge carrier. 7 In systems of current technological interest, where intensive research is being carried out, this is further aggravated due to factors like structural disorder appearing in organic polymers 6 or magnetic disorder associated with the metal−insulator transition of the manganites. 3 The main goal of this work is to study in-depth the stability and dynamics of a small polaron formed in a model system using first-principles calculations.…”

Section: Introductionmentioning

confidence: 99%

“…1 This idea of a localized charge carrier composed of an electron (or hole) and its surrounding lattice distortion, called a polaron, has had a strong influence in later research and is nowadays often invoked to explain many attractive phenomena, such as high-temperature superconductivity in the cuprates 2,3 or colossal magnetoresistance in manganites. 2,4,5 Furthermore, polarons play a key role in explaining transport in organic materials (both natural, like light-harvesting molecules in plants 6 or proteins key to the vision process in animals, 7 and artificial, 8 like organic light emitting diodes and transistors) or the performance of Li−air batteries in which materials such as Li 2 O 2 and Li 2 CO 3 are involved. 9 However, understanding in-detail the dynamics of these quasi-particles is far from trivial.…”

Section: Introductionmentioning

confidence: 99%

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Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides: Insight through DFT+UCalculations

et al. 2016

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Polarons and their associated transport properties are a field of great current interest both in chemistry and physics. In order to further our understanding of these quasi-particles, we have carried out first-principles calculations of self-trapped holes (STH) in the model compounds AgCl and AgBr, where extensive experimental information exists. Our calculations confirm that the STH solely stabilizes in AgCl but with a binding energy of only 165 meV, an order of magnitude smaller than that found for the Vk center in KCl. Key contributions to this stabilization energy come from the local relaxation along breathing (a1g) and Jahn-Teller (eg) modes in the AgCl6 4-unit. In order to study the transfer of the STH among silver sites we (i) use first-principles calculations to obtain the hopping barrier of the STH to first and second neighbors, involving eight distinct paths, using firstprinciples and (ii) construct a simple model, based on Slater-Koster parameters, that highlights the similarity of polaron transfer with magnetic superexchange. This allows one understanding why the movement of STH to second neighbors is highly enhanced with respect to closer ones. In agreement with experimental data and the model, the present calculations prove the existence of a dominant mechanism of polaronic motion that corresponds to the displacement of the STH to the next nearest sites in the <100> direction and a small barrier of 37 meV. This mechanism is dominated by the covalency inside a AgX6 4-complex (X:Cl;Br) thus explaining why the STH is not stabilized in AgBr following the increase of covalency due to the ClBr substitution. The present calculations confirm that ~10% of the charge associated with the STH in AgCl is lying outside the AgCl6 4-complex. This fact is behind the differences between optical and magnetic properties of the STH in AgCl and those observed in KCl:Ag 2+ .2

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Section: Origin Of the Hopping Barriers: Simplementioning

confidence: 72%

Section: T H Imentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides: Insight through DFT+UCalculations

et al. 2016

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“…This issue is important because charge-excitation type determines the range of photoinduced optoelectronic applications for conducting polymers. Prior studies , using ultrafast pump and probe spectroscopy have shown that photon injection excites electrons from the valence band to the polaron band. The polaron state is an intermediately doped state lying below the conduction band edge (Figure a).…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Spin-Resolved Spectroscopy Reveals Dominant Exciton Dynamics in Conducting Polymer Polyaniline

et al. 2013

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The conducting polymer polyaniline (PANI) has a wide range of optoelectronic applications due to its unique electronic and optical characteristics. Although extensive works have been performed to understand the equilibrium properties, the nature of the charge type that governs its non-equilibrium optical response has been barely understood; a number of studies have debated the nature of photo-generated charge type in PANI, specifically whether it is polaron or exciton based. Here, we report experimental evidence that the charge relaxation dynamics of PANI are dominated by excitons. Utilizing ultrafast spin-resolved pump-probe spectroscopy, we observed that PANI charge dynamics are strongly spin-polarized, exhibiting a spin Pauli-blocking effect. Investigations including both spin-independent and spindependent dynamics reveal that there is no spin-flip process involved in charge relaxation.This provides compelling evidence of an exciton-dominated photo-response in PANI.

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Ultrafast photophysical studies of sulfonated polyaniline in aqueous medium by femtosecond transient absorption spectroscopy

Majhi

Sinha

2022

Preprint

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In our previous work (Khatun et al., J. Phys. Chem. A 122 (2018) 7089-7098), synthesis and characterization of sulfonated polyaniline (SPANI) were discussed. Photophysical properties of SPANI in aqueous medium were also investigated using steady state spectroscopic techniques, which suggested the co-existence of two conformations (‘A’ and ‘B’) of SPANI in the normal working low acidic medium. Also, combined red-edge effect was observed from the two conformations of SPANI in aqueous medium. In the present work, a detailed investigation is carried out on the ultrafast photophysical properties of SPANI in aqueous medium by employing femtosecond transient absorption spectroscopy based on pump-probe technique. It is found that excited state absorption from the S1 state of SPANI in aqueous medium to higher electronic states originates mostly due to the conformation ‘A’ in the whole spectral range and very weakly due to the conformation ‘B’ on the blue side of the spectra. These new findings are extremely important keeping in mind various potential applications of SPANI in the field of polymer optoelectronics.

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Ultrafast Dephasing of Photoexcited Polarons in Primary Doped Polyaniline

Cited by 3 publications

References 6 publications

Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides: Insight through DFT+UCalculations

Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides: Insight through DFT+UCalculations

Ultrafast Spin-Resolved Spectroscopy Reveals Dominant Exciton Dynamics in Conducting Polymer Polyaniline

Ultrafast photophysical studies of sulfonated polyaniline in aqueous medium by femtosecond transient absorption spectroscopy

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