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[MDI-MTP-Charge Localization induced Tunable Thermopower in ZnSb Intercalated Polyaniline CSA Flexible Films.pdf](https://mdr.nims.go.jp/filesets/818366c0-233c-487f-a31a-b1c582668859/download)

## Creator

[Anmol Sharma](https://orcid.org/0009-0004-8877-3645), [Nagendra Singh Chauhan](https://orcid.org/0000-0003-2579-6642), Masako Nishimagi, [Takao Mori](https://orcid.org/0000-0003-2682-1846)

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[Charge Localization induced Tunable Thermopower in ZnSb Intercalated Polyaniline:CSA Flexible Films](https://mdr.nims.go.jp/datasets/2be93055-290c-4f93-bcd4-c3e00fa5885d)

## Fulltext

1  Charge Localization induced Tunable Thermopower in ZnSb Intercalated 1 Polyaniline:CSA Flexible Films 2  3 Anmol Sharma1,2, Nagendra Singh Chauhan1∗, Masako Nishimagi3 and Takao Mori1,2∗  4  5 1Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-6 1, Tsukuba, 305-0044, Japan. 7 2Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, 8 Japan. 9 3ZACROS Corporation Ltd. Tokyo, 112-0002, Japan. 10  11 Abstract 12  13 Modulating doping levels and nanofillers blending has facilitated optimization of electrical 14 properties in polymeric nanocomposite films for thermoelectric applications. Herein we report, 15 free-standing flexible films of PANI:CSA/ZnSb polymer nanocomposites, with varying 16 nanofillers ZnSb ratios, to realize charge localization induced enhancement in power factor (≈ 10 17 times) and thermopower (≈ 6 times) within the protonated PANI:CSA. Le Bail refinement of the 18 XRD pattern reveals lattice expansion and reoriented chain conformation in the pseudo-19 orthorhombic PANI structure due to ZnSb intercalation. The thermopower, enhanced to ≈ 50 μV/K 20 at room temperature, was tunable due to the suppressed bipolaronic states and associated charge 21 localization, resulting in an improved power factor of ≈ 10 μW/m·K2 . The synthesized polymeric 22 films exhibit excellent mechanical durability, retaining ~90% of their electrical conductivity after 23 2000 bending cycles. A flexible thermoelectric generator (FTEG) fabricated using six 24 PANI:CSA/70 wt.% ZnSb  films produced an output voltage of ~0.9 mV on a human wrist and 25 ~6.7 mV under a temperature gradient of ~50 K, highlighting prospects of charge localization in 26 improving the low and smeared Seebeck response in conducting polymers like PANI and their 27 potential for wearable thermoelectric energy harvesting applications.  28 Keywords – Thermoelectrics; Polyaniline; Localization; Intercalation; Conducting Polymers 29  *CHAUHAN.NagendraSingh@nims.go.jp, MORI.Takao@nims.go.jp  2  1. Introduction. Amidst rising energy demand globally and depleting natural resources, 1 thermoelectric (TE) energy harvesting is emerging as a promising green technology that enables 2 efficient conversion of waste heat energy into electricity. As a sustainable approach to enhance the 3 efficacy of thermal energy conversion, TE applications are expanding to enable the harnessing of 4 low-grade heat sources accessible at dynamic surfaces such as human body, and portable devices 5 operating at the microwatt scale.[1,2] In this context, polymeric TE electronic materials have shown 6 great prospects for flexible and wearable applications, with ongoing research aimed towards 7 optimizing their electronic transport properties.[3,4] For decoupling the inversely related Seebeck 8 coefficient (𝑆𝑆)  and electrical conductivity (𝜎𝜎) , various polymer engineering approaches aims 9 towards maximizing the power factor (𝑆𝑆2𝜎𝜎).[1,3–5] These approaches typically includes (i) precise 10 control of oxidation level/doping through electrochemical methods; (ii) use of secondary dopants 11 (with organic protic acids such as HCl, H2SO4, HClO4, CSA) to improve morphology and increase 12 polarons/bipolarons;[6,7] and (iii) formation of polymer nanocomposites with fillers such as carbon 13 nanomaterials or inorganic nanoparticles.[8–12]  14 Amongst actively explored conducting polymers, PANI and their derivatives are well 15 recognized for their low cost, tunable energy levels, ease in processability, and near ambient 16 chemical stability.[13,14] Depending on the synthesis conditions, i.e., chemical, electrochemical, 17 or plasma methods, PANI can occur in diverse structural forms and varying degree of 18 crystallinity.[15–18] For TE applications, PANI based nanocomposites having an inherently low 19 thermal conductivity (𝜅𝜅) has garnered much attention owing to their high and tunable σ (ranging 20 from 10−13 – 10 S/cm) though simple and often reversible protonic doping.[19–22] The 21 protonation adds positive charges (holes) i.e. polarons (singly charged, spin 1/2) and at higher 22 doping levels bipolarons (doubly charged, spin 0), onto the conjugated polymer backbone 23 coupling local structural distortion and electrostatically balancing the charges, as shown in Figure 24 1(a). Amongst studied protic acids (i.e., acid that donates protons, or hydrogen ions, to an aqueous 25 3  solution), camphor sulfonic acid (CSA), being bulky and hydrophobic, is often preferred as it 1 enables better processability and σ tunability.[19,23] Moreover, higher CSA doping has remained 2 most consistent and effective in degree of protonation per repeat unit,[24–27] typically tuned by 3 molar ratio as indicated in Figure 1(b). Typically, with increasing polaron/bipolaron concentration, 4 hole density (n) increases, promoting delocalization driven by an enhanced overlap between π-5 orbitals and improved interchain connectivity via π–π stacking. However, higher n from increased 6 doping often results in broadening of transport energy levels, limiting and reducing the S ~ 10 7 μV/K for protonated PANI. Moreover, inhomogeneous polaron distribution coupled with 8 energetically broad and smeared energy distributions, results in a smeared thermopower response 9 for many structural or doping changes, studied in PANI based nanocomposite films hybridized 10 with inorganic materials such as Te[28], PbTe[29], Bi2Te3[30], Bi0.5Sb1.5Te3[31], Ag[32,33], 11 Ag2Te[34], CdS[35], Bi2Se3[36], and SnSeS[37].  12 Developing PANI-based flexible nanocomposite films with improved conductivity and 13 tunable Seebeck coefficient remains challenging due to their heterogeneous structure, complex 14 interchain interactions, and charge transport dominated by localization, hopping, and chain 15 disorder.[38–40] Herein, we investigate the electrical transport behavior in free-standing flexible 16 films of ZnSb nanofillers intercalated PANI:CSA polymer nanocomposites synthesized by 17 solution mixing. Self-supporting films were drop-casted using m-cresol as solvent and subsequent 18 delamination in deionized water.[26] Balancing flexibility in an emeraldine salt state (having 19 intrinsically high σ), the ordered crystalline coordination complexes (ZnSb clusters and metallic 20 islands) surrounded by disordered amorphous regions within the heterogeneous nanocomposites 21 structure, contribute to charge localization.[41] The carrier transport behavior as a function of 22 temperature suggests moderate doping that fits well with the ES-VRH model, accounting for 23 Coulomb interactions and a soft gap in the density of states (DOS).[42,43] The ZnSb nanofillers 24 intercalate between amorphous or semi-ordered domains without significantly disrupting the bulk 25 4  crystalline regions, as indicated by minimal changes in unit cell parameters. However,  ZnSb 1 intercalation while causing lattice expansion and reoriented chain conformation introduces 2 localized states that suppress bipolaron formation and favor polaron transport, thereby enhancing 3 both the thermopower and power factors. 4 2. Results & Discussion. 5 2.1 Free-standing Flexible Film, Granular Morphology, and Molecular Configuration. 6 The synthesis by CSA-doping and ZnSb nanofillers additions in PANI yielded a free-standing 7 flexible dark green film, even for a significantly higher ZnSb content (~ up to 70%) as shown in 8 Figure 2. The co-occurrence of protonation (with CSA) and hybridization with ZnSb nanofiller 9 simultaneously in m-cresol (a polar protic solvent) under stirring and ultrasonication has enabled 10 better dissolution and regulation of the doping level. For cooperative alignment between PANI 11 chains and CSA molecules, m-cresol plays a unique role in enhancing chain ordering and planarity, 12 by strengthening hydrogen bonding with both –S𝑂𝑂3− group of CSA and protonated nitrogen (–13 𝑁𝑁𝐻𝐻+ ) of the PANI backbone.[19] Moreover, m-cresol enables coil to extended chain 14 transformation in PANI, thereby promoting planarization, better π–π stacking and interchain 15 connectivity.[44,45] A scheme of our synthesis of PANI:CSA/ZnSb polymeric nanocomposites is 16 presented in Figure 2. The synthesized free-standing films show superior flexibility, with the 17 absence of any cracking on their surfaces for up to 70% ZnSb loading. However, it may be noted 18 that prolonged exposure to oxidizing surroundings was found to degrade PANI chains. 19 The morphology and microstructure of the representative PANI  film surfaces, both with and 20 without ZnSb nanofillers incorporated PANI:CSA, were analyzed by SEM micrographs. In Figure 21 3(a), the SEM micrograph of PANI:CSA film shows a smooth and dense surface film without any 22 visible cracks and pores. Upon ZnSb nanofiller addition, the polymeric chain retains granular 23 morphology with ZnSb interlinked nanoparticle structures as shown in Figure 3(b – f). Also, at 24 higher ZnSb content (> 60 wt.%), agglomerations of ZnSb nanofillers in the range of ~20-30 μm 25 5  in size with granular features of size in range ~100 – 500 nm, were observed as shown in Figure 1 3(e – f). This amorphous or poorly ordered microstructure is representative of the disrupted 2 morphology at high ZnSb loading, which interrupts the conductive polymer network. This 3 morphological disorder likely contributes to the observed decline in electrical conductivity due to 4 reduced carrier mobility and impaired percolation pathways. Elemental mapping through energy-5 dispersive X-ray microanalysis was simultaneously conducted to investigate the distribution of 6 elements in PANI:CSA and ZnSb-incorporated PANI: CSA films. The relevant elemental maps 7 for Zinc (Zn), Antimony (Sb), Carbon (C), Nitrogen (N), and Sulfur (S), are presented in Figure 8 3(g – m). As seen in the elemental mapping images of Nitrogen (–𝑁𝑁𝑁𝑁+–), nitrogen was also 9 detected in the ZnSb regions, indicating an interaction between the charged amine group and ZnSb. 10 The polymeric layer thicknesses were also corroborated by the surface profiler and analyzing the 11 transversal cross-section of each polymer with the SEM technique, as shown in Figure 3(n – o). 12 The average thickness of the pristine PANI:CSA, and PANI:CSA/70 wt% ZnSb are 128 µm and 13 25 µm, respectively. Here, a decrease in the thickness of the nanocomposite film was observed 14 with an increase in ZnSb filler, indicating space-filling and densification of the film. This reduction 15 may be attributed to the occupation of interstitial voids between PANI chains by ZnSb 16 nanoparticles, resulting in higher packing density and reduced local porosity, as also seen in 17 previous studies.[46,47] Furthermore, increasing the ZnSb content while maintaining a fixed 18 amount of PANI:CSA in m-cresol likely reduces the polymer fraction, contributing to the thinner 19 films observed in the PANI:CSA/70 wt.% ZnSb sample during drop-casting.  20 2.2 Structural Parameters, Semi Crystallinity and Orthorhombic Symmetry. The 21 XRD measurements of the synthesized PANI:CSA shown in Figure 4(a) indicate semi-crystallinity, 22 as evidenced by fewer and broader diffraction peaks, also shown in a magnified view (2θ ~ 10 – 23 25°) in Figure 4(b). Although partial crystallinity makes accurate determination of the crystal 24 structure challenging, XRD patterns reveal a broad amorphous region (2θ ~ 10 – 25°), centering 25 6  around 2θ ~ 20 - 22° for synthesized films, which aligns well with previously reported diffraction 1 patterns.[48,49] Nevertheless, the observed XRD patterns are generally consistent with a pseudo-2 orthorhombic lattice symmetry for crystalline domains of PANI:CSA complex, in which 3 protonated polymer chains and CSA anions pack into a unit cell with approximate lattice 4 parameters a ≈ 7.0 – 7.1 Å, b ≈ 7.9 – 8.6 Å, c ≈ 10.4 A˚ as reported previously by Pouget et al.[50]  5 The orthorhombic structure (Space group: Pbca, 61)[51] of ZnSb and the pseudo-orthorhombic 6 (Space group: Pc2a, 32)[48,49] arrangement of PANI is expected to ensure structural 7 compatibility within the composite, minimizing interfacial strain and preserving chemical stability. 8 For conceptual visualization only, molecularly disordered (PANI:CSA) with crystalline (ZnSb) 9 phases are overlayed/merged randomly to attain simulated powder XRD patterns shown alongside 10 based on periodic atomic positions,[52] which surprisingly matches well with the measured XRD 11 patterns. The synthesized unfilled protonated PANI:CSA films display partial order with indexed 12 pseudo-orthorhombic diffraction peaks shown in Figure 4(c) and listed in Table 1, characteristics 13 of PANI semicrystalline structure. The evaluated d-spacing for refined structure indicates close 14 agreement with values and (hkl) indexation for stretched films, made previously for emeraldine 15 PANI:HCl salt samples.[50]  16 In the synthesized PANI:CSA, m-cresol treatment may be ascribed to an increased π–π d-17 spacing, indicating backbone separation and extended conjugation.[45] As indicated in Figure 4(d), 18 the peak maximum corresponding to the (112) planes, with a d-spacing of approximately 4 Å, 19 represents the face-to-face interchain stacking distance between phenyl rings along the conjugated 20 polymer backbones. The low angle shift is indicative of a weaker π–π interaction induced by ZnSb 21 intercalation which increased d-spacing by ≈ 1.5 times. For ZnSb hybridized PANI:CSA films, the 22 XRD pattern constitutes a low-angle shift having both broad amorphous regions, and sharp peaks 23 revealing crystalline domains, as shown in Figure 4(a). An alteration in backbone periodicity peaks 24 (2θ ≈ 10 – 20°) is clearly observed, which indicates an expanded lamellar stacking or long-range 25 7  periodicity along the polymer chain (i.e. spacing between doped regions or structural repeats). 1 Moreover, rearrangement of side chains or counterions with ZnSb intercalation may induce 2 disruption in chain stacking (c-axis), typically related to peak changes at 2θ ~ 20 – 22° for 3 PANI:CSA complex. Additionally, ZnSb fillers may occupy interstitial spaces within the PANI 4 matrix, reducing the volume of amorphous regions, wherein ZnSb clusters induce an altered 5 stacking order, different internal packing, or domain alignment by disrupting the PANI chains. 6 The cell parameters and crystallite size of the synthesized film were determined using the 7 Le Bail method, assuming the pseudo-orthorhombic crystal structure (Space group: Pc2a, 32) for 8 the PANI:CSA Complex.[48,49] The ZnSb nanofillers intercalation in polymer nanocomposites is 9 evaluated to result in an expanded interlayer spacings, broadening of existing peaks and peak 10 maxima occurring for new planes i.e. (103) and (211) as indicated in Table 1 and supplementary 11 figure S4 – S8. The refined lattice parameter for pseudo-orthorhombic PANI:CSA Complex, 12 suggest a higher lattice parameter for the synthesized unfilled PANI:CSA films, when compared 13 with stretched films analyzed by Pouget et al.[50] shown in Figure 5(a). Interestingly, despite low 14 angle shift upon ZnSb intercalation when compared to unfilled PANI:CSA for the synthesized 15 films, only marginal changes in pseudo-orthorhombic unit cell parameters were evaluated. 16 Moreover, the average lattice constants (a, b, c) from the crystalline fraction for both pseudo-17 orthorhombic PANI:CSA complex and orthorhombic ZnSb (Figure 5b) remain mostly unaffected. 18 This may imply an anisotropic structural change, where ZnSb intercalation may occur only along 19 the chain stacking (c-axis), causing an anisotropic expansion which averages out due to a marginal 20 shift in hkl planes. Moreover, as PANI:CSA complex constitutes large amorphous domains with 21 only smaller proportions of crystalline domains, ZnSb intercalation may only expand or distort the 22 amorphous regions, with minimal penetration into crystalline zones. Thus, we conclude that d-23 spacing for different planes increases locally upon ZnSb intercalation, affecting intermolecular 24 8  distances largely, while causing marginal distortion to the crystalline domains of  PANI:CSA and 1 ZnSb nanofillers, implying structural compatibility. 2 Although the orthorhombic symmetry match was anticipated to help in attaining an ordered 3 PANI:CSA complex with periodic hybrid layers, to retain the intrinsic electronic 4 structure, preventing degradation or distortion of functional sites, thereby maintaining the charge 5 transport properties essential for TE performance. However, for higher ZnSb content (i.e. >50 %), 6 Sb, ZnS, and ZnO were also identified as additional phases, which is anticipated to be driven by 7 low formation energy of Zn vacancies (𝑉𝑉Zn2−). While Zn vacancies typically act as acceptor defects, 8 leading to hole generation (i.e., p-type conduction), Zn atoms tendency to form coordination 9 complexes in the presence of strongly acidic sulfonic group (–SO3H) in organosulfur CSA 10 compounds, may disrupts the π-conjugated system in PANI:CSA complex. The Zn – Sb binary 11 system encompasses two notable thermoelectric materials: the ordered phase ZnSb and the 12 disordered phase Zn13Sb10, both having multicenter bonding within Zn2Sb2 rhombic structural 13 units. The ZnS and ZnO demixing may electrostatically balance PANI:CSA complex, implying 14 their existence as unreacted clusters when ZnSb nanofillers exceed the percolation threshold or 15 saturation limit of the PANI:CSA matrix. This can convert polarons/bipolarons into neutral or 16 localized states depending on Zn vacancies. Additionally, decomposition of ZnSb phase may 17 interact with charged sites on PANI chains due to co-occurrence of protonation (with CSA) and 18 ZnSb nanofiller hybridization. The alterations in interchain π–π stacking between polymer 19 backbones, in the coherence length (along both the chain direction and perpendicular to it) and the 20 interchain spacing significantly impact the determination of the balance between the localization 21 of electronic charges on individual chains and their delocalization within the 3D-crystalline 22 regions.[41]  23 2.3 Bonding Interactions, Charge Localization, and Raman Spectra. The coherence 24 length (both along and across the chain direction), and interchain spacing are critical factors 25 9  influencing the balance between electronic charge localization on a single chain and charge 1 delocalization across three-dimensional crystalline regions. To analyze the chemical interactions 2 between the PANI backbone chain and ZnSb in PANI composites, Raman microscopy was 3 performed on PANI:CSA and its ZnSb nanocomposites to analyze shifts in semi-quinoid and 4 polaron peaks. The pristine PANI spectra (Figure 6) shows distinct peaks corresponding to the 5 emeraldine salt form, including peaks at 415, 513, 578, 717, 810, 1173, 1268, 1340, 1375, 1496, 6 1590, and 1622 cm-1. The peaks at 415, 513, 578, 717, and 810 cm-1  are attributed to out-of-plane 7 ring deformation in PANI salt, out-of-plane C-N-C-H vibrations, phenazine-type cross-linking, C-8 N-C deformation vibrations, and Benzene ring distortion in emeraldine salt. The peaks at 1173, 9 1268, 1340, 1375, 1496, 1590, and 1622 correspond to C-H bending vibrations of quinonoid (QN) 10 units, C-N stretching in semi-QN structures, 𝐶𝐶 − 𝑁𝑁+∙ stretching modes of the benzenoid (BZ) and 11 QN cation radicals within delocalized polaronic structures which accounts for conducting-ES form, 12 𝐶𝐶 − 𝑁𝑁+∙ stretching vibrational modes in strongly localized polarons, N-H stretching vibrational 13 modes of QN and BZ rings, C-C stretching modes of the QN and BZ rings (delocalized polaron 14 vibration), and phenazine-like crosslinking (C=C stretching vibrational modes of QN and BZ 15 rings).[25,53,54]  16 As ZnSb content increases, the peak at 1622 cm-1 decreases in intensity and undergoes a 17 blue shift, indicating reduced quinoid units leading to lowered σ. The peaks at 1590 and 1496 cm⁻¹ 18 also shift upwards, suggesting increased oxidation, increased localization of polarons, and changes 19 in changes in protonation level. The peak at 1375 cm-1 (negligible for pristine PANI-CSA) 20 increases in intensity and shifts to 1378 cm-1 (for 70 wt% ZnSb/PANI), indicating the presence of 21 highly localized polaron states trapping the polarons, which is anticipated to reduce both holes 22 concentration and their mobility.[53,54] Additionally, the peak at 1340 cm-1 shifts slightly 23 downwards, verifying the presence of delocalization on semi-quinoid units, while the peak at 1268 24 cm-1 shifts down slightly, indicating reduced C-N bonding. Other shifts in peaks (810, 415, 717, 25 10  578, and 513 cm⁻¹) further confirm the chemical interaction between ZnSb and PANI:CSA. To 1 analyze the Raman spectra qualitatively, the intensity ratio of specific Raman peaks for PANI:CSA 2 with its 70wt.% ZnSb hybridized counterpart, was evaluated and shown in Table S1 3 (Supplementary information). The intensity ratio I1 (i.e. I1(1340)/I1(1590) = 1.28) & I3 (i.e. 4 I3(1337)/I3(1600) = 1.05) corresponds to polaronic delocalization or the doping level, which 5 decreases as ZnSb is introduced, suggesting reduced σ. While the intensity I2 (i.e. I2(1375)/I2(1590) 6 = 0 (as no peak was observed) for PANI:CSA) & I4 (i.e. I4(1378)/I4(1600) = 0.94) ratios correspond 7 to charge localization. While optimal protonation level in all the synthesized films sustains 8 polaron-bipolarons equilibrium for work function tuning, the positive charge delocalization in the 9 polymer chain imparts enhanced stability of polarons near the anion site.[16]  10 The X-ray photoelectron spectroscopy (XPS) was conducted to examine the chemical 11 states in the PANI:CSA/70 wt% ZnSb nanocomposite flexible film, as shown in Figure 7. The 12 XPS-wide scan, as shown in Figure 7(a), reveals signature peaks corroborating the presence of C, 13 N, S, Zn, Sb, and O in PANI:CSA/ZnSb polymeric nanocomposites. In Figure 7(b), the sharp C 14 1s peak is shown at ~285 eV, representing different carbon environments in PANI and CSA, while 15 the N 1s spectrum corresponds to different nitrogen states in PANI (e.g., neutral, polaron, 16 bipolarons), as shown in Figure 7(c). The superimposed peaks at ~399.3 eV, ~399.95 eV, ~400.85 17 eV, and ~402.3 eV correspond to imine (=N-), amine (-NH-), polarons, and bipolarons (both being 18 protonated nitrogen (N+)), respectively. Similar peaks were also shown by Dezhuang et al.[55], 19 for pure PANI and PANI/SWCNT. The S 2p spectrum confirms the presence of CSA dopants, 20 showing two peaks at 168 and 169 eV, attributed to the sulfonic group from camphor sulfonic acid, 21 with a binding energy range of ~167–171 eV. The high-resolution Zn 2p doublet, with two peaks 22 at ~1023.3 and ~1046.5 eV for Zn 2p3/2 and Zn 2p1/2, indicates Zn2+ oxidation state. Similarly, the 23 Sb 3d spectrum exhibits peaks at ~532.1 and ~540.8 eV for Sb 3d5/2 and Sb 3d3/2, which overlap 24 with O 1s peaks, showing high intensity and correspond to its presence in PANI:CSA. For 25 11  comparison, the wide scan survey spectra for PANI:CSA is shown in Figure S12.[56–58] To 1 further elucidate the chemical structure modulated by ZnSb incorporation, high-resolution N 1s 2 XPS spectra was deconvoluted for PANI:CSA and PANI:CSA/70 wt.% ZnSb nanocomposite 3 films, respectively. The N 1s spectra, as shown in Figure 8(a) & (b), reveal four distinct nitrogen 4 components corresponding to imine (=N–), amine (–NH–), polaronic, and bipolaronic nitrogen 5 species, as also observed previously for deconvoluted N 1s spectra.[55] 6 In pristine PANI:CSA, peaks are observed at ~399.3 eV (=N–), ~399.5 eV (–NH–), 7 ~400.85 eV (polaron), and ~402.9 eV (bipolaron), with corresponding concentration contributions 8 of 21.05%, 30.76%, 27.83%, and 20.36%, respectively. In contrast, the PANI:CSA/70 wt.% ZnSb 9 nanocomposite exhibits the same chemical assignments with slight shifts: ~399.3 eV (=N–), 10 ~399.95 eV (–NH–), ~400.85 eV (polaron), and ~402.3 eV (bipolaron). However, the spectral 11 concentrations are significantly redistributed to 40.78%, 23.95%, 31.97%, and 3.30%, respectively. 12 These deconvoluted peaks reflect a significant decrease in bipolaron content (down to 3.30% from 13 20.36%) and a marked increase in imine nitrogen (~94% relative rise), suggesting a reduction in 14 the overall oxidation state of the PANI matrix upon ZnSb loading. The suppression of bipolaron 15 states, along with a ~0.6 eV downshift in the bipolaron peak, indicates either their trapping or 16 conversion to polarons. This behavior suggests partial charge localization at the ZnSb–PANI 17 interface, likely induced by interfacial energy barriers or trap states introduced by the ZnSb phase. 18 The moderate increase in polaronic content (N⁺ from 27.83% to 31.97%) indicates stabilization of 19 single-charge carriers, while the reduced –NH– peak intensity points to partial deprotonation or 20 chemical restructuring of amine sites under interfacial strain or charge transfer. The overall 21 decrease in the proportion of charged nitrogen species (polaron + bipolaron) relative to total 22 nitrogen supports the observed moderate decline in electrical conductivity. These changes are 23 shown in supplementary Table S2 & S3. 24 12  The UV–Vis absorbance spectra of pristine PANI:CSA and the PANI:CSA/70 wt.% ZnSb 1 composite films are shown in Figure 9. The overall absorbance intensity is higher in PANI:CSA 2 across the full spectral range, suggesting a more extended π-conjugated system, whereas the lower 3 absorbance in the composite indicates partial disruption of conjugation upon ZnSb incorporation. 4 In the deep UV region (200–280 nm), PANI:CSA exhibits a sharp absorption band at ~212 nm, 5 which redshifts to ~215.5 nm in the composite. This feature may arise from aromatic ring-related 6 transitions or residual solvent interactions i.e., m-cresol.[12] A secondary transition around 253 7 nm in PANI:CSA, also observed in the composite at ~251.5 nm, is attributed to π–π* transitions 8 within the benzenoid segments of the polymer backbone. The slight redshift and suppression of 9 these bands in the ZnSb-loaded film suggest local electronic perturbations and possible changes in 10 π-stacking or chain conformation.[12,59,60] In the visible region (300–400 nm), both samples 11 show a polaron–π* transition, a key signature of charge delocalization in doped PANI. This band 12 appears at ~391 nm for PANI:CSA and shifts to ~397 nm in the composite, accompanied by a 13 noticeable reduction in intensity. These changes may indicate partial localization of polarons and 14 disruption of extended charge transport pathways, consistent with a transition from delocalized to 15 more localized carrier states. In the near-infrared region (800–900 nm), a broad absorption feature 16 at ~859 nm is evident in PANI:CSA, corresponding to π–polaron transitions associated with 17 bipolaron formation in the highly doped state.[12,59,60]  18  In the PANI:CSA/70 wt.% ZnSb composite, this band intensity is suppressed and 19 redshifted to ~881 nm, suggesting a reduction in bipolaron delocalization and the emergence of a 20 more localized electronic structure. Similar peaks and trends of solvent traces, π–π* transitions, 21 polaron–π* transition,  and π–polaron transitions were seen is several studies.[12,59,60] This 22 spectroscopic evidence aligns with XPS N 1s analysis, which also suggests a notable reduction in 23 bipolaron content in the composite film. Collectively, UV–Vis–NIR and XPS results confirm that 24 ZnSb incorporation significantly modulates the redox and electronic structure of PANI, shifting 25 13  the equilibrium toward neutral and polaronic states while suppressing bipolaron formation and 1 extended charge delocalization. Such evolution toward a more localized electronic structure is 2 indicative of charge carrier confinement, a mechanism that likely contributes to the observed 3 enhancement in Seebeck coefficient and overall thermoelectric performance while partially 4 deteriorating the electrical conductivity. 5 2.4. Charge Localization Induced Tunable Thermopower and Enhanced Power 6 Factor.  In PANI:CSA/ZnSb nanocomposite films, CSA, being a bulky and flexible anion, helps 7 uncoil the PANI backbone, enhancing planarity and π-orbital overlap between adjacent chains, 8 particularly when processed with m-cresol.[19] At high enough doping (∼50% protonation), the 9 synthesized PANI:CSA as shown in Figure 10(a), with σ ~102 S/cm behaves like a degenerate 10 semiconductor or a dirty metal (i.e. σ(T) decreases with increasing temperature), suggesting 11 presence of quasi-metallic conduction pathways having improved interchain delocalization.[19–12 21] Moreover, σ(T) decreases with increasing ZnSb content, suggesting interface scattering and 13 possible disruption in the ordered regions of PANI:CSA, causing localization of charge carriers as 14 confirmed by Raman  and XPS analysis. The pristine PANI:CSA exhibits an electrical 15 conductivity of ~148 S/cm at 323 K, which drops to 40 S/cm in PANI:CSA/70 wt% ZnSb 16 nanocomposite films. To account for Coulomb interactions between localized charge carriers 17 during hopping or variable-range hopping transport, the Efros–Shklovskii variable range hopping 18 (ES-VRH) model is employed, which accounts for the formation of a soft gap in the density of 19 states near the Fermi level.[42,61,62] The temperature-dependent carrier transport analyzed using 20 the ES-VRH mode fits well with the temperature-dependent σ(T) as indicated in Figure 10(b).  21 Notably, the temperature dependence T-1/2 exponent distinguishes ES-VRH from Mott VR 22 and accounts for long-range Coulomb interactions between localized charge carriers, which form 23 a soft gap in the DOS close to the Fermi level. As intercalation of ZnSb into PANI:CSA complex 24 results in an expanded interlayer spacing, with inherent structural disorder, localization effects that 25 14  may impede charge carrier mobility. The evaluated activation energy (Ea), as shown in Figure 1 10(c), exhibits a slight and non-monotonic increase with increasing ZnSb content. The increased 2 charge carrier scattering from ZnSb centers and charge localization observed with higher ZnSb 3 content results in a decreased carrier concentration (n) and carrier mobility (μ), as verified by Hall 4 measurements near room temperature shown in Figure 10(d). In conjugated polymer systems, both 5 energetic and spatial disorder can serve as charge-trapping centers, ultimately reducing carrier 6 mobility. 7 The temperature-dependent variation of the Seebeck coefficient, S(T), for the synthesized 8 PANI:CSA/ZnSb nanocomposite films is presented in Figure 10(e), displays a positive value of 9 Seebeck coefficient confirming p-type behavior, characteristics of protonated PANI-based 10 nanocomposites, rich in polarons and bipolarons, both of which are hole-like carriers. The S(T) for 11 π conjugated polymers as validated by Watanabe et al.[62] based on Mott formula, is expressed 12 as[61,62] 13 𝑆𝑆 ∝  𝑚𝑚∗𝑇𝑇 �1𝑛𝑛�23� (1)  where 𝑚𝑚∗, T, and n correspond to charge carrier effective mass, temperature, and charge carrier 14 concentration. This equation suggests that the Seebeck coefficient rises with increasing 15 temperature or decreasing n, as observed in the synthesized polymer nanocomposites. The S(T) 16 for all the PANI films showing inverse relation with σ(T) increases with temperature as shown in 17 Figure 8(f), which is attributed to reduced carrier concentration and increased phonon scattering 18 mechanisms at elevated temperatures.  19 With increasing contents of ZnSb nanofillers in the PANI matrix, the Seebeck coefficient 20 is substantially increased. At 323 K, the smeared Seebeck coefficient of PANI:CSA film is 21 typically observed to be  ≤ 10 µV/K, due to their inhomogeneous polaron distribution caused local 22 variation in carrier energy level. Thus, energetically broad and smeared DOS, often led to low and 23 15  insensitive S for moderate structural or doping changes.[7] For 70 wt% ZnSb/PANI nanocomposite 1 film, the S was increased to ≈ 50 µV/K (~ 6 times) at 323 K and up to ~ 60 µV/K at 373 K. The 2 higher value of the S corresponds to lowering n as shown by Hall measurement, reduction in 3 bipolarons level that may lead to charge localization as suggested by Raman, XPS, and UV-vis 4 NIR analysis.[41,56–58] By introducing localized states or affecting the band structure, ZnSb may 5 induce an asymmetric DOS near the Fermi level,[64] also implied by altered and distorted structure 6 hybridized PANI:CSA/ZnSb nanocomposite films and XPS spectra. Such asymmetry favors 7 higher S, as it depends on the difference in the average energy of electrons above and below the 8 Fermi level. Thus, existence of both partially delocalized and localized states, introduced via ZnSb 9 intercalation, leads to a combined effect of reduced σ and an increased S, wherein the partial 10 delocalization probably comes from existing singly charged polarons levels as seen from XPS 11 study, and the partial localization states probably arise from suppressed bipolarons level 12 significantly.  13 Figure 11(a) shows a plot of electrical conductivity versus Seebeck coefficient for reported 14 PANI-based nanocomposites with our reported 𝜎𝜎 vs. 𝑆𝑆 values, showing inverse correlation and a 15 largely low values of S attained for polymer nanocomposites. Figure 11(b) demonstrates an inverse 16 and varying relationship between S(T) and σ(T) with varying ZnSb content and temperature (373 17 – 293 K) from right to left, suggestive of weak localization and non-degenerate transport 18 regime.[61,62] As a semi-conductive filler, the distribution, morphology, and interfacial 19 phenomena of intercalated ZnSb nanoparticles within polymeric PANI:CSA matrix promote 20 charge localization, while for high protonation level i.e. polarons and bipolarons in PANI:CSA 21 complex promotes delocalization.[41] Figure 11(c) shows the PF of the PANI:CSA and 22 PANI:CSA/ZnSb nanocomposite films. The value of the power factor can be calculated from a 23 simple expression (PF = S2𝜎𝜎). A higher PF ~ 10 µW/m.K2 at 333 K is calculated for 70 wt% 24 ZnSb/PANI nanocomposite film, 10 times larger than the pristine PANI:CSA film (PF ~ 1 25 16  µW/m.K2), thus highlighting the prospect of structurally compatible semiconducting fillers for 1 improving and tuning the S effectively. To assess the impact of oxidative and humid exposure, 2 electrical measurements after ~2 months showed slight reductions in conductivity and Seebeck 3 coefficient, likely due to PANI chain degradation (Figure S13, Supplementary Section S6). 4 Further enhancement of the power factor may be achieved by increasing charge carrier 5 mobility through the incorporation of surface-functionalized carbon nanotubes (CNTs) or 6 graphene or structural reordering via post-synthesis treatments that enhance backbone planarity 7 and conjugation length, thereby promoting long-range charge transport. Figure 11(d) compares 8 various studies, highlighting that while most have focused on Tellurium (Te)-based fillers, herein 9 we employ a widely recognized, non-toxic, Te-free material ZnSb nanofillers blending in 10 PANI:CSA to achieve power factor optimization. Additionally, co-doping and hybridization with 11 metal oxides (e.g., TiO2, Fe2O3, CuO), 2D materials (such as MoS2, WS2, and MXenes), represent 12 a promising direction for future development of PANI based nanocomposite films for 13 thermoelectric applications.  14 2.5. Fabrication of Flexible Thermoelectric Generator (FTEG). To assess the practical 15 applicability of the optimized PANI:CSA/70 wt.% ZnSb nanocomposite, a flexible device 16 constituting patterned composite legs (~ 15 × 5 mm² each) on a Kapton (polyimide) substrate. As 17 shown in Figure 12(a), the legs were connected in series with silver contacts, and copper wires 18 were attached using silver paste to ensure good ohmic contact. The device was tested under two 19 conditions: (i) body heat harvesting, where it was attached to a human forearm using Kapton tape, 20 generating an output voltage (VOC) ~ 0.9 mV from a ~10 K skin-to-air temperature gradient (∆T) 21 (Figure 12b); and (ii) hot plate heating, where it produced up to ~6.7 mV at a ~50 K gradient 22 (Figure 12c), consistent with the reported values.[26,28,55,56] The device retained its flexibility 23 and stable performance during attachment to curved surfaces, demonstrating its robustness and 24 feasibility for wearable electronics demanding body-conformable adaptability.   25 17  3. Conclusion. We report flexible, free-standing PANI:CSA and PANI:CSA/ZnSb 1 nanocomposite films via solution drop-casting, with intercalation of ZnSb nanofillers attained in m-2 cresol medium. Lattice expansion and reoriented chain conformation with a marginal variation in 3 unit cell parameters, was evaluated for pseudo-orthorhombic PANI:CSA complex upon 4 orthorhombic ZnSb nanofillers intercalation, which disrupts original ordering and led to emergence 5 of new crystalline domains. Raman spectra confirm conformational changes and charge localization 6 in the polymer matrix, while XPS and UV-Vis-NIR analyses indicate a transition from bipolaronic 7 to polaronic states, accompanied by changes in oxidation state and doping levels, consistent with 8 Hall measurement results. These findings suggest that incorporating semiconducting fillers like 9 ZnSb into conducting polymers modulates charge transport by suppressing bipolaron formation and 10 increasing carrier scattering and localization, leading to an improved Seebeck coefficient (≈ 50 11 µV/K) and power factor (≈ 10 µW/m·K2) at room temperature for higher ZnSb content. A flexible 12 thermoelectric generator (FTEG) fabricated with six PANI:CSA/70 wt.% ZnSb nanocomposite films 13 generated ~0.9 mV on a human wrist, and ~6.7 mV under a 50 K temperature gradient, showcasing 14 its possible practical potential. Thus, semiconducting nanofillers induced charge localization 15 presents a promising strategy for tuning the Seebeck coefficient and enhancing the power factor, 16 thereby enabling the development of flexible TE films suited for wearable electronics and body heat 17 recovery, especially where mechanical flexibility and environmental compatibility are essential  18 Associated Content.  19 Supporting Information. Details of experimental procedures for ZnSb synthesis, 20 PANI:CSA/ZnSb hybrid film fabrication, and characterization methods. Additional data include 21 structural parameters, crystallographic analysis, SEM images, key Raman intensity ratios with 22 interpretations, bending test results, XPS survey spectra, and aging stability assessments. 23 18  Acknowledgment. This work was supported by the JST Mirai Program, Japan, Grant Number 1 JPMJMI19A1. A.S. gratefully acknowledges financial support from JST, the establishment of 2 university fellowships towards the creation of science technology innovation, Grant Number 3 JPMJFS 2106.  4 Conflict of Interest: There is no conflict of interest to declare. 5 Data availability statement:  The data that supports the findings of this study are available upon 6 request from the authors. 7   8 19  TABLES 1 Table 1. (hkl) indexation based on pseudo-orthorhombic lattice symmetry (Space group: Pc2a, 32) 2 of PANI:CSA complex in emeraldine salt proposed by Pouget et al.[50] and evaluated d Spacing 3 of synthesized PANI:CSA/ZnSb nanocomposite films. 4 (hkl) Pouget et al.[50]  This Work PANI:CSA PANI : CSA/ZnSb Nanocomposite Films 30% 40% 50% 60% 70% (010) 7.88 7.85 - - - - - (101) 5.87 5.95 8.79 8.80 8.74 8.84 8.83 (002) - 5.40 7.51 7.51 7.48 7.41 7.42 (111) - 4.93 6.54 6.53 6.51 6.56 6.54 (012) 4.38 4.61 5.92 5.92 5.91 5.86 5.86 (102) 4.18 4.43 5.68 5.68 5.66 5.67 5.67 (020) - 4.27 5.21 5.20 5.19 5.19 5.17 (112) - 3.97 4.86 4.86 4.85 4.85 4.85 (200) 3.57 3.76 4.61 4.60 4.59 4.68 4.67  (201) - 3.57 4.32 4.31 4.30 4.37 4.37 (121) - 3.56 4.17 4.16 4.16 4.16 4.15 (210) 3.24 3.45 4.13 4.12 4.11 4.17 4.16 (022) - 3.44 3.98 3.98 3.98 3.96 3.94  5  6   7 20  FIGURES 1  2 Figure 1. (a) Generic structure of emeraldine base form of polyaniline, which transforms to 3 emeraldine salt form, constituting polarons and bipolarons. (b) Dependence of electrical 4 conductivity vs. protic acid concentration.[24–27]  5  6 21  1 Figure 2. Schematic representing fabrication process of flexible PANI:CSA/ZnSb nanocomposite 2 free-standing film. 3 22   1 Figure 3. (a – f) SEM micrographs illustrating the granular morphology of ZnSb clusters with 2 increasing ZnSb content. (g – m) EDX elemental mapping of the marked region highlights the 3 distinct distribution of ZnSb clusters within the polymeric PANI matrix. (n – o) SEM image of 4 cross-section of PANI:CSA & PANI:CSA/70 wt.% ZnSb nanocomposite film, respectively. 5 23   1 Figure 4. (a) X-Ray diffraction patterns of pristine PANI:CSA, and PANI:CSA/ZnSb (30 – 70 2 wt.%) nanocomposite films, (b) Characteristic reflection corresponding to PANI:CSA complex 3 shown in a magnified range, (c) Le Bail refined structure implying pseudo-orthorhombic symmetry 4 (Pc2a, 32), with corresponding (d) d-spacing for unfilled PANI:CSA complex.  5 24   1 Figure 5. Refined lattice parameter for pseudo-orthorhombic (a) PANI:CSA Complex with empty 2 symbols corresponding to values evaluated by Pouget et al.[50] (b) Orthorhombic ZnSb phase in 3 PANI:CSA/ZnSb nanocomposite vs. ZnSb content. 4  5  6 25   1  2 Figure 6. Raman spectra of the PANI:CSA, and PANI:CSA/ZnSb (30 –  70 wt. %) nanocomposite 3 films. 4   5  6 26   1 Figure 7. (a) XPS survey spectra; (b) –(f) high resolution peaks of C 1s, N 1s, S 2p, Sb 3d, and Zn 2 2p, respectively, of the :PANI:CSA/70 wt.% ZnSb  nanocomposite film. 3 4 Figure 8. Deconvoluted N 1s XPS spectral peaks for (a) PANI:CSA, & (b) PANI:CSA/70 wt.% 5 ZnSb nanocomposite film 6 27  1 Figure 9. UV–Vis–NIR absorption spectra analysis of PANI:CSA and PANI:CSA/70 wt.% ZnSb 2 composite films. 3 28   1 Figure 10. Temperature dependence of (a) electrical conductivity, (b) ES-VRH model fitting with 2 a temperature exponent of 1/2 demonstrating linear behavior, (c) activation energy derived for 3 variable-range hopping conduction, (d) carrier concentration and mobility as a function of ZnSb 4 content from room-temperature Hall measurements, (e) Seebeck coefficient variation with 5 temperature, and (f) the inverse relationship between the Seebeck coefficient and electrical 6 conductivity for PANI:CSA and ZnSb-incorporated PANI:CSA nanocomposite flexible films at 7 varying ZnSb Weight percentages. 8  9 29  Figure 11. (a) Electrical conductivity as a function of the Seebeck coefficient for reported PANI-1 based nanocomposites[28–35]; (b) Jonker plot illustrating the relationship between Seebeck 2 coefficient and electrical conductivity; (c) Temperature-dependent power factor of PANI-based 3 materials; and (d) Comparison of reported power factor values for PANI-based 4 nanocomposites[28–34]. 5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20 30   1  2 Figure 12. Flexible thermoelectric device based on PANI:CSA/70 wt.% ZnSb: (a) Device 3 schematic on Kapton substrate with alternating PANI:CSA/70 wt.% ZnSb nanocomposite flexible 4 films; (b) On-body demonstration under body heat; (c) Output under hot plate-induced ΔT; (d) 5 Output voltage (Vo) vs. ΔT confirming thermoelectric response. 6   7 31  References  1 [1] S. Xu, X.-L. Shi, M. Dargusch, C. Di, J. Zou, Z.-G. Chen, Conducting polymer-based flexible 2 thermoelectric materials and devices: From mechanisms to applications, Progress in 3 Materials Science 121 (2021) 100840. https://doi.org/10.1016/j.pmatsci.2021.100840. 4 [2] T. Mori, S. Priya, Materials for energy harvesting: At the forefront of a new wave, MRS Bull. 5 43 (2018) 176–180. https://doi.org/10.1557/mrs.2018.32. 6 [3] G. Prunet, F. Pawula, G. Fleury, E. Cloutet, A.J. Robinson, G. Hadziioannou, A. Pakdel, A 7 review on conductive polymers and their hybrids for flexible and wearable thermoelectric 8 applications, Materials Today Physics 18 (2021) 100402. 9 https://doi.org/10.1016/j.mtphys.2021.100402. 10 [4] M. Bharti, A. Singh, S. Samanta, D.K. Aswal, Conductive polymers for thermoelectric power 11 generation, Progress in Materials Science 93 (2018) 270–310. 12 https://doi.org/10.1016/j.pmatsci.2017.09.004. 13 [5] I. Petsagkourakis, K. Tybrandt, X. Crispin, I. Ohkubo, N. Satoh, T. Mori, Thermoelectric 14 materials and applications for energy harvesting power generation, Science and Technology 15 of Advanced Materials 19 (2018) 836–862. https://doi.org/10.1080/14686996.2018.1530938. 16 [6] Z. Zhang, Z. Wei, M. Wan, Nanostructures of Polyaniline Doped with Inorganic Acids, 17 Macromolecules 35 (2002) 5937–5942. https://doi.org/10.1021/ma020199v. 18 [7] M. Pope, C.E. Swenberg, Electronic Processes in Organic Crystals and Polymers, Second 19 Edition, Oxford University PressNew York, NY, 1999. 20 https://doi.org/10.1093/oso/9780195129632.001.0001. 21 [8] N. Nandihalli, C.-J. Liu, T. Mori, Polymer based thermoelectric nanocomposite materials and 22 devices: Fabrication and characteristics, Nano Energy 78 (2020) 105186. 23 https://doi.org/10.1016/j.nanoen.2020.105186. 24 [9] Y. Wang, H. Pang, Q. Guo, N. Tsujii, T. Baba, T. Baba, T. Mori, Flexible n -Type Abundant 25 Chalcopyrite/PEDOT:PSS/Graphene Hybrid Film for Thermoelectric Device Utilizing Low-26 Grade Heat, ACS Appl. Mater. Interfaces 13 (2021) 51245–51254. 27 https://doi.org/10.1021/acsami.1c15232. 28 [10] Y. Wang, R. Chetty, Z. Liu, L. Wang, T. Ohsawa, W. Gao, T. Mori, A facile route to 29 fabricating a crack-free Mg0.99 Cu0.01 Ag0.97 Sb0.99 /graphene/PEDOT:PSS thermoelectric film 30 on a flexible substrate, J. Mater. Chem. C 10 (2022) 12610–12620. 31 https://doi.org/10.1039/D2TC02176E. 32 [11] A.K. Yadav, N. Mohammad, E. Chamanehpour, Y.K. Mishra, P.K. Khanna, Polyaniline 33 (PANI) nanocomposites with Se, Te and their metal chalcogenides: a review, RSC Appl. 34 Polym. 2 (2024) 775–794. https://doi.org/10.1039/D4LP00093E. 35 [12] H. Li, Y. Liang, Y. Liu, S. Liu, P. Li, C. He, Engineering doping level for enhanced 36 thermoelectric performance of carbon nanotubes/polyaniline composites, Composites 37 Science and Technology 210 (2021) 108797. 38 https://doi.org/10.1016/j.compscitech.2021.108797. 39 [13] A.G. Macdiarmid, J.-C. Chiang, M. Halpern, W.-S. Huang, S.-L. Mu, L.D. Nanaxakkara, 40 S.W. Wu, S.I. Yaniger, “Polyaniline”: Interconversion of Metallic and Insulating Forms, 41 Molecular Crystals and Liquid Crystals 121 (1985) 173–180. 42 https://doi.org/10.1080/00268948508074857. 43 [14] P. Kaushik, R. Bharti, R. Sharma, M. Verma, R.T. Olsson, A. Pandey, Progress in synthesis 44 and applications of Polyaniline-Coated Nanocomposites: A comprehensive review, European 45 Polymer Journal 221 (2024) 113574. https://doi.org/10.1016/j.eurpolymj.2024.113574. 46 32  [15] G.-R. Li, Z.-P. Feng, J.-H. Zhong, Z.-L. Wang, Y.-X. Tong, Electrochemical Synthesis of 1 Polyaniline Nanobelts with Predominant Electrochemical Performances, Macromolecules 43 2 (2010) 2178–2183. https://doi.org/10.1021/ma902317k. 3 [16] J. Scotto, M.I. Florit, D. Posadas, About the species formed during the electrochemical half 4 oxidation of polyaniline: Polaron-bipolaron equilibrium, Electrochimica Acta 268 (2018) 5 187–194. https://doi.org/10.1016/j.electacta.2018.02.066. 6 [17] R. Djara, Y. Holade, A. Merzouki, N. Masquelez, D. Cot, B. Rebiere, E. Petit, P. Huguet, C. 7 Canaff, S. Morisset, T.W. Napporn, D. Cornu, S. Tingry, Insights from the Physicochemical 8 and Electrochemical Screening of the Potentiality of the Chemically Synthesized Polyaniline, 9 J. Electrochem. Soc. 167 (2020) 066503. https://doi.org/10.1149/1945-7111/ab7d40. 10 [18] N. Sirotkin, A. Khlyustova, Plasma Synthesis and Characterization of PANI + WO3 11 Nanocomposites and their Supercapacitor Applications, J. Compos. Sci. 7 (2023) 174. 12 https://doi.org/10.3390/jcs7040174. 13 [19] Q. Yao, Q. Wang, L. Wang, Y. Wang, J. Sun, H. Zeng, Z. Jin, X. Huang, L. Chen, The 14 synergic regulation of conductivity and Seebeck coefficient in pure polyaniline by chemically 15 changing the ordered degree of molecular chains, J. Mater. Chem. A 2 (2014) 2634–2640. 16 https://doi.org/10.1039/C3TA14008C. 17 [20] A.B. Kaiser, Systematic Conductivity Behavior in Conducting Polymers: Effects of 18 Heterogeneous Disorder, Adv. Mater. 13 (2001) 927–941. https://doi.org/10.1002/1521-19 4095(200107)13:12/13<927::AID-ADMA927>3.0.CO;2-B. 20 [21] A.B. Kaiser, V. Skákalová, Electronic conduction in polymers, carbon nanotubes and 21 graphene, Chem. Soc. Rev. 40 (2011) 3786. https://doi.org/10.1039/c0cs00103a. 22 [22] S. Sinha, S. Bhadra, D. Khastgir, Effect of dopant type on the properties of polyaniline, J of 23 Applied Polymer Sci 112 (2009) 3135–3140. https://doi.org/10.1002/app.29708. 24 [23] H. Yan, T. Ohta, N. Toshima, Stretched Polyaniline Films Doped by (±)-10-Camphorsulfonic 25 Acid: Anisotropy and Improvement of Thermoelectric Properties, Macromol. Mater. Eng. 26 286 (2001) 139–142. https://doi.org/10.1002/1439-2054(20010301)286:3<139::AID-27 MAME139>3.0.CO;2-F. 28 [24] C. Nath, A. Kumar, Y.-K. Kuo, G.S. Okram, High thermoelectric figure of merit in 29 nanocrystalline polyaniline at low temperatures, Applied Physics Letters 105 (2014) 133108. 30 https://doi.org/10.1063/1.4897146. 31 [25] M. Singh, A.K. Gautam, M. Faraz, N. Khare, Thermoelectric performance of (±) Camphor-32 10-sulfonic acid doped polyaniline/graphitic carbon nitride composite films, Eur. Phys. J. 33 Plus 137 (2022) 1251. https://doi.org/10.1140/epjp/s13360-022-03451-7. 34 [26] M. Singh, A.K. Gautam, M. Faraz, N. Khare, Flexible, Freestanding Ternary Nanocomposite 35 Thick Film of Polyaniline/WS2 /CNTs for Efficient Thermoelectric Application, ACS Appl. 36 Energy Mater. 7 (2024) 133–144. https://doi.org/10.1021/acsaem.3c02331. 37 [27] D. Geethalakshmi, N. Muthukumarasamy, R. Balasundaraprabhu, CSA-doped PANI 38 semiconductor nanofilms: synthesis and characterization, J Mater Sci: Mater Electron 26 39 (2015) 7797–7803. https://doi.org/10.1007/s10854-015-3427-z. 40 [28] Y. Wang, S.M. Zhang, Y. Deng, Flexible low-grade energy utilization devices based on high-41 performance thermoelectric polyaniline/tellurium nanorod hybrid films, J. Mater. Chem. A 4 42 (2016) 3554–3559. https://doi.org/10.1039/C6TA01140C. 43 [29] Y.Y. Wang, K.F. Cai, J.L. Yin, B.J. An, Y. Du, X. Yao, In situ fabrication and thermoelectric 44 properties of PbTe–polyaniline composite nanostructures, J Nanopart Res 13 (2011) 533–45 539. https://doi.org/10.1007/s11051-010-0043-y. 46 [30] K. Chatterjee, M. Mitra, K. Kargupta, S. Ganguly, D. Banerjee, Synthesis, characterization 47 and enhanced thermoelectric performance of structurally ordered cable-like novel 48 33  polyaniline–bismuth telluride nanocomposite, Nanotechnology 24 (2013) 215703. 1 https://doi.org/10.1088/0957-4484/24/21/215703. 2 [31] C. Guo, F. Chu, P. Chen, J. Zhu, H. Wang, L. Wang, Y. Fan, W. Jiang, Effectively enhanced 3 thermopower in polyaniline/Bi0.5Sb1.5Te3 nanoplate composites via carrier energy 4 scattering, J Mater Sci 53 (2018) 6752–6762. https://doi.org/10.1007/s10853-017-1958-9. 5 [32] W. Wang, S. Sun, S. Gu, H. Shen, Q. Zhang, J. Zhu, L. Wang, W. Jiang, One-pot fabrication 6 and thermoelectric properties of Ag nanoparticles–polyaniline hybrid nanocomposites, RSC 7 Adv. 4 (2014) 26810–26816. https://doi.org/10.1039/C4RA02136C. 8 [33] F. Roussel, R. Chen Yu King, M. Kuriakose, M. Depriester, A. Hadj-Sahraoui, C. Gors, A. 9 Addad, J.-F. Brun, Electrical and thermal transport properties of polyaniline/silver 10 composites and their use as thermoelectric materials, Synthetic Metals 199 (2015) 196–204. 11 https://doi.org/10.1016/j.synthmet.2014.11.020. 12 [34] Y.Y. Wang, K.F. Cai, J.L. Yin, Y. Du, X. Yao, One-pot fabrication and thermoelectric 13 properties of Ag2Te–polyaniline core–shell nanostructures, Materials Chemistry and Physics 14 133 (2012) 808–812. https://doi.org/10.1016/j.matchemphys.2012.01.098. 15 [35] P.V. More, C. Hiragond, A. Dey, P.K. Khanna, Band engineered p-type RGO–CdS–PANI 16 ternary nanocomposites for thermoelectric applications, Sustainable Energy Fuels 1 (2017) 17 1766–1773. https://doi.org/10.1039/C7SE00290D. 18 [36] M. Mitra, C. Kulsi, K. Kargupta, S. Ganguly, D. Banerjee, Composite of polyaniline‐bismuth 19 selenide with enhanced thermoelectric performance, J of Applied Polymer Sci 135 (2018) 20 46887. https://doi.org/10.1002/app.46887. 21 [37] H. Ju, D. Park, J. Kim, Fabrication of Polyaniline-Coated SnSeS Nanosheet/Polyvinylidene 22 Difluoride Composites by a Solution-Based Process and Optimization for Flexible 23 Thermoelectrics, ACS Appl. Mater. Interfaces 10 (2018) 11920–11925. 24 https://doi.org/10.1021/acsami.7b19667. 25 [38] W. W. Focke, G. E. Wnek, Conduction mechanisms in polyaniline (emeraldine salt), Journal 26 of Electroanalytical Chemistry and Interfacial Electrochemistry 256 (1988) 343–352. 27 https://doi.org/10.1016/0022-0728(88)87008-6. 28 [39] G. Tzamalis, N.A. Zaidi, C.C. Homes, A.P. Monkman, Doping-dependent studies of the 29 Anderson-Mott localization in polyaniline at the metal-insulator boundary, Phys. Rev. B 66 30 (2002) 085202. https://doi.org/10.1103/PhysRevB.66.085202. 31 [40] K. Lee, S. Cho, S. Heum Park, A.J. Heeger, C.-W. Lee, S.-H. Lee, Metallic transport in 32 polyaniline, Nature 441 (2006) 65–68. https://doi.org/10.1038/nature04705. 33 [41] N.J. Pinto, P.K. Kahol, B.J. McCormick, N.S. Dalal, H. Wan, Charge transport and electron 34 localization in polyaniline derivatives, Phys. Rev. B 49 (1994) 13983–13986. 35 https://doi.org/10.1103/PhysRevB.49.13983. 36 [42] A.L. Efros, M. Pollak, Electron-Electron Interactions in Disordered Systems, in: March 1, 37 De Gruyter, 1986: pp. 497–498. https://doi.org/10.1515/9783112494721-070. 38 [43] S. Shekhar, V. Prasad, S.V. Subramanyam, Anomalous Efros–Shklovskii variable range 39 hopping conduction in composites of polymer and iron carbide nanoparticles embedded in 40 carbon, Physics Letters A 360 (2006) 390–393. 41 https://doi.org/10.1016/j.physleta.2006.08.043. 42 [44] L.W. Shacklette, Dipole and hydrogen-bonding interactions in polyaniline: a mechanism for 43 conductivity enhancement, Synthetic Metals 65 (1994) 123–130. 44 https://doi.org/10.1016/0379-6779(94)90173-2. 45 [45] K.-H. Lee, B.J. Park, D.H. Song, I.-J. Chin, H.J. Choi, The role of acidic m-cresol in 46 polyaniline doped by camphorsulfonic acid, Polymer 50 (2009) 4372–4377. 47 https://doi.org/10.1016/j.polymer.2009.07.009. 48 34  [46] P. Sekar, B. Anothumakkool, S. Kurungot, 3D Polyaniline Porous Layer Anchored Pillared 1 Graphene Sheets: Enhanced Interface Joined with High Conductivity for Better Charge 2 Storage Applications, ACS Appl. Mater. Interfaces 7 (2015) 7661–7669. 3 https://doi.org/10.1021/acsami.5b00504. 4 [47] C. Yang, L. Zhang, N. Hu, Z. Yang, Y. Su, S. Xu, M. Li, L. Yao, M. Hong, Y. Zhang, Rational 5 design of sandwiched polyaniline nanotube/layered graphene/polyaniline nanotube papers 6 for high-volumetric supercapacitors, Chemical Engineering Journal 309 (2017) 89–97. 7 https://doi.org/10.1016/j.cej.2016.09.115. 8 [48] E.A. Sanches, A.D.S. Carolino, A.L.D. Santos, E.G.R. Fernandes, D.M. Trichês, Y.P. 9 Mascarenhas, The Use of Le Bail Method to Analyze the Semicrystalline Pattern of a 10 Nanocomposite Based on Polyaniline Emeraldine-Salt Form and α -Al2 O3, Advances in 11 Materials Science and Engineering 2015 (2015) 1–8. https://doi.org/10.1155/2015/375312. 12 [49] D. Djurado, Y.F. Nicolau, I. Dalsegg, E.J. Samuelsen, X-ray scattering study of CSA 13 protonated polyaniline films and powders, Synthetic Metals 84 (1997) 121–122. 14 https://doi.org/10.1016/S0379-6779(97)80675-3. 15 [50] J.P. Pouget, M.E. Jozefowicz, A.J. Epstein, X. Tang, A.G. MacDiarmid, X-ray structure of 16 polyaniline, Macromolecules 24 (1991) 779–789. https://doi.org/10.1021/ma00003a022. 17 [51] T.B.E. Grønbech, H. Kasai, J. Zhang, E. Nishibori, B.B. Iversen, Weak Bonding and 18 Anharmonicity in Thermoelectric ZnSb, Adv Funct Materials 34 (2024) 2401703. 19 https://doi.org/10.1002/adfm.202401703. 20 [52] V. Petkov, V. Parvanov, P. Trikalitis, C. Malliakas, T. Vogt, M.G. Kanatzidis, Three-21 Dimensional Structure of Nanocomposites from Atomic Pair Distribution Function Analysis: 22 Study of Polyaniline and (Polyaniline)0.5 V2 O5 ·1.0H2 O, J. Am. Chem. Soc. 127 (2005) 23 8805–8812. https://doi.org/10.1021/ja051315n. 24 [53] S.A. Ture, V.B. Patil, C.V. Yelamaggad, R. Martínez‐Máñez, V. Abbaraju, Understanding 25 of mechanistic perspective in sensing of energetic nitro compounds through spectroscopic 26 and electrochemical studies, J of Applied Polymer Sci 138 (2021) 50776. 27 https://doi.org/10.1002/app.50776. 28 [54] Z. Morávková, P. Bober, Writing in a Polyaniline Film with Laser Beam and Stability of the 29 Record: A Raman Spectroscopy Study, International Journal of Polymer Science 2018 (2018) 30 1–8. https://doi.org/10.1155/2018/1797216. 31 [55] D. Ji, B. Li, B.T. Raj, X. Li, D. Zhang, M. Rezeq, W. Cantwell, L. Zheng, In Situ Surface 32 Polymerization of PANI/SWCNT Bilayer Film: Effective Composite for Improving Seebeck 33 Coefficient and Power Factor, Adv Materials Inter 12 (2025) 2400566. 34 https://doi.org/10.1002/admi.202400566. 35 [56] L. Wang, Q. Yao, W. Shi, S. Qu, L. Chen, Engineering carrier scattering at the interfaces in 36 polyaniline based nanocomposites for high thermoelectric performances, Mater. Chem. Front. 37 1 (2017) 741–748. https://doi.org/10.1039/C6QM00188B. 38 [57] X. Guan, J. Ouyang, Enhancement of the Seebeck Coefficient of Organic Thermoelectric 39 Materials via Energy Filtering of Charge Carriers, CCS Chem 3 (2021) 2415–2427. 40 https://doi.org/10.31635/ccschem.021.202101069. 41 [58] S.A. Gregory, R. Hanus, A. Atassi, J.M. Rinehart, J.P. Wooding, A.K. Menon, M.D. Losego, 42 G.J. Snyder, S.K. Yee, Quantifying charge carrier localization in chemically doped 43 semiconducting polymers, Nat. Mater. 20 (2021) 1414–1421. 44 https://doi.org/10.1038/s41563-021-01008-0. 45 [59] V. Ugraskan, F. Karaman, Polyaniline/Graphitic Carbon Nitride Nanocomposites with 46 Improved Thermoelectric Properties, Journal of Elec Materi 50 (2021) 3455–3461. 47 https://doi.org/10.1007/s11664-021-08856-1. 48 35  [60] R. Nayak, P. Shetty, S. M, A. Rao, S. K V, S. Wagle, S. Nayak, V. Kamath, N. Shetty, M. 1 Saquib, Formulation and optimization of copper selenide/PANI hybrid screen printing ink 2 for enhancing the power factor of flexible thermoelectric generator: A synergetic approach, 3 Ceramics International 50 (2024) 25779–25791. 4 https://doi.org/10.1016/j.ceramint.2024.04.315. 5 [61] D. Venkateshvaran, M.T.R. Cervantes, L.J. Spalek, K.-H. Hwang, K. Pudzs, M. Rutkis, G. 6 Schweicher, P. Padilla-Longoria, Understanding the Thermoelectric Transport Properties of 7 Organic Semiconductors through the Perspective of Polarons, Adv Devices Instrum 5 (2024) 8 0067. https://doi.org/10.34133/adi.0067. 9 [62] S. Watanabe, M. Ohno, Y. Yamashita, T. Terashige, H. Okamoto, J. Takeya, Validity of the 10 Mott formula and the origin of thermopower in π -conjugated semicrystalline polymers, Phys. 11 Rev. B 100 (2019) 241201. https://doi.org/10.1103/PhysRevB.100.241201. 12 [63] J. Liu, Y. Shi, J. Dong, M.I. Nugraha, X. Qiu, M. Su, R.C. Chiechi, D. Baran, G. Portale, X. 13 Guo, L.J.A. Koster, Overcoming Coulomb Interaction Improves Free-Charge Generation and 14 Thermoelectric Properties for n-Doped Conjugated Polymers, ACS Energy Lett. 4 (2019) 15 1556–1564. https://doi.org/10.1021/acsenergylett.9b00977. 16 [64] M. Duhandžić, M. Lu-Dìaz, S. Samanta, D. Venkataraman, Z. Akšamija, Carrier Screening 17 Controls Transport in Conjugated Polymers at High Doping Concentrations, Phys. Rev. Lett. 18 131 (2023) 248101. https://doi.org/10.1103/PhysRevLett.131.248101. 19  20