Highly Conductive Films Through PEDOT‐PSS Ink Formulation via Doping Using Spontaneous Wicking of Liquids for Supercapacitor Applications

A novel electrode fabrication method based on liquid doping of PEDOT‐PSS onto PET‐G film by drop casting is reported. A dispersed liquid‐PEDOT‐PSS solution is prepared as an ink by a liquid doping synthesis method. The EG/DMSO:PEDOT‐PSS solution is then drop cast onto oxygen plasma‐modified PET‐G films for electrode fabrication. Their surface topography and electrochemical characteristics are characterized. The results show that the prepared electrode material has an electrical conductivity of 11661.7 and 11528.8 S m−1 for EG‐ and DMSO‐treated PEDOT‐PSS films, respectively. Ink formulation achieves unprecedented conductivity via spontaneous liquid wicking. The specific capacitance is 134 F g−1 at a scanning rate of 5 mV s−1 and 309.6 F g−1 at a scanning rate of 20 mV s−1 for EG and DMSO‐treated PEDOT‐PSS films, respectively, on the three‐electrode system while specific capacitance for pristine PEDOT‐PSS calculated at 80 mV s−1 is 4.6 F g−1. PEDOT‐PSS films are engineered for superior supercapacitor performance through liquid wicking. Moreover, the results of Fourier‐transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and Raman spectroscopy measurements confirm that the removal of PSS on the surface is due to liquid–liquid doping. Energy‐dispersive X‐ray spectroscopy analysis proves the expulsion of PSS molecules from the solution interface. Therefore, the die‐cast PET‐G‐PEDOT‐PSS electrode is a promising candidate for advanced supercapacitor applications.


Introduction
The need to develop high-performance energy storage materials has promoted the development of high-performance energy storage devices.3][4][5][6][7][8] Supercapacitors are the most permissible energy storage materials for various applications such as smart and wearable clothes, [9,10] hybrid electric vehicles, [11] and automobiles (regenerative braking). [12]hey are used in applications that require fast charge and discharge cycles.Supercapacitors have many advantages.Among them, ease of large-scale production, high energy and power density, and long life cycles [13] are of high demand.
Various materials, including bio-based activated carbons, [14,15] graphene, [14,16] carbon nanotubes (CNTs), [16,17] conductive polymers, [18] and nanofibers, [18,19] have been extensively studied to obtain highperformance supercapacitors.Among the list, conductive polymers especially PEDOT-PSS [20][21][22][23][24] have been studied to meet the demands of high-energy-density supercapacitor electrodes.PEDOT-rGO/HKUST-1 has been employed to produce high-performance symmetrical supercapacitor devices. [25][28] However, the intrinsic conductivity of PEDOT-PSS is limited.For this reason, researchers have used the various conductivity enhancing mechanisms to enhance the conductivity of PEDOT-PSS including treating the polymer using several solutions such as ethylene glycol (EG) and methanol, [29] dimethyl sulfoxide (DMSO), [30] sulfuric acid, [31] and formic acid. [32]But the methods of treatment in both mechanisms are using small ratios of solutions when compared to PEDOT-PSS quantities and most researchers have used 5% of the liquid solution against PEDOT-PSS.However, a recent study has shown the reverse options.That is the ratio of liquids when compared to that of PEDOT-PSS is high.The research conducted in Ref. [33] used a liquid-liquid contact method with ratio of 14:500 (PEDOT-PSS to ethylene glycol).However, an extremely high amount of ethylene glycol was used and may not be recommended in terms of cost.DOI: 10.1002/aesr.202400006A novel electrode fabrication method based on liquid doping of PEDOT-PSS onto PET-G film by drop casting is reported.A dispersed liquid-PEDOT-PSS solution is prepared as an ink by a liquid doping synthesis method.The EG/DMSO:PEDOT-PSS solution is then drop cast onto oxygen plasma-modified PET-G films for electrode fabrication.Their surface topography and electrochemical characteristics are characterized.The results show that the prepared electrode material has an electrical conductivity of 11661.7 and 11528.8S m À1 for EG-and DMSOtreated PEDOT-PSS films, respectively.Ink formulation achieves unprecedented conductivity via spontaneous liquid wicking.The specific capacitance is 134 F g À1 at a scanning rate of 5 mV s À1 and 309.6 F g À1 at a scanning rate of 20 mV s À1 for EG and DMSO-treated PEDOT-PSS films, respectively, on the three-electrode system while specific capacitance for pristine PEDOT-PSS calculated at 80 mV s À1 is 4.6 F g À1 .PEDOT-PSS films are engineered for superior supercapacitor performance through liquid wicking.Moreover, the results of Fouriertransform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and Raman spectroscopy measurements confirm that the removal of PSS on the surface is due to liquid-liquid doping.Energy-dispersive X-ray spectroscopy analysis proves the expulsion of PSS molecules from the solution interface.Therefore, the die-cast PET-G-PEDOT-PSS electrode is a promising candidate for advanced supercapacitor applications.
The present work involves the synthesis of plasma surfacemodified electrically conductive glycol modified version of polyethylene terephthalate (PET-G) films obtained from drop casting with highly conductive PEDOT-PSS doped with liquids for supercapacitor electrode preparation.The PET-G film was drop cast with treated PEDOT-PSS polymer.The PET-G film was treated with plasma surface modification before drop casting.The samples were then characterized to evaluate their suitability for supercapacitor applications.The performance of PET-G film was assessed using a three-electrode measurement setup in a Na 2 SO 4 water-based electrolyte.Electrodes crafted from PEDOT-PSS treated with ethylene glycol (EG) and dimethyl sulfoxide (DMSO) exhibited the most favorable electrochemical performance.
The drop-casting method is widely employed in crafting electrodes for supercapacitors.This process involves enhancing the substrate's surface through plasma treatment, coupled with the improved dispersion and adhesion of the conductive polymer PEDOT-PSS, achieved through doping with EG and DMSO.Groundbreaking PEDOT-PSS ink preparation achieved superlative conductivity through spontaneous liquid wicking for supercapacitors.In this work, novel PEDOT-PSS ink formulation employs spontaneous liquid wicking for exceptional supercapacitor performance with greater adhesion properties.After drop casting, it is not possible to peel off the PEDOT-PSS film on the surface of PET-G films mechanically.

Experimental Section 2.1. Preparation of Conductive PEDOT-PSS Film with Liquid Doping
All chemicals in the experiments were of analytical grade and used as received without further purification.Ten milliliters of ethylene glycol (99.8% anhydrous, Thermo Fisher Scientific Inc.) and dimethyl sulfoxide (99.9%,Naturverlesen Co., Ltd, Blumberg, Germany) were slowly dropped to a container (half conical) whose top height and diameter were 95 and 15 mm, and bottom height and diameter were 25 and 3 mm, respectively.PEDOT-PSS solution (1.3 wt% dispersion in water, conductive grade (Sigmar Aldrich) was added slowly drop wise to the surface of EG and DMSO.Finally, the sealed solution was kept at the fume hood for a specified time without further treatment (Figure 1a,b).The polyethylene terephthalate-glycol (PET-G) (Vivak Exolon Group GmbH) film was oxygen plasma-modified for 20 min using electronic plasma surface technology (Diener Plasma GmbH & Co. KG, Ebhausen, Germany) (Figure 1c).After that, 400 μL of the PEDOT-PSS was carefully taken and utilized to drop cast onto a 20 mm Â 15 mm polyethylene terephthalate glycol (PET-G) sheet (Figure 1d).The films were cleaned by isopropyl alcohol before drop casting.Drop casting was performed immediately (5-10 min) after oxygen plasma surface modification.After the samples were applied to the surface of the PET-G film, the PEDOT-PSS construct aligned itself  [29,58] g) drying of the coated film at 55 °C, h) dried film, and i) characterization of the conductive films using impedance spectroscopy.
(Figure 1e,f ).The samples then were dried at 55 °C for 8 h (Figure 1g). Figure 1h shows the dried PEDOT-PSS-coated PET-G films.It was then measured and analyzed in the threeelectrode setup (Figure 1i).The entire process is shown in Figure 1.

Characterization and Measurements
The electrical conductivity and sheet resistance of the treated samples were acquired by Ossilla four-point probe (Ossilla Ltd, UK).Ossilla four-point probe was calibrated in house and evaluated using a certified indium tin oxide (ITO) sheet resistance standard which can be traced to the NIST and VLSI.The standard was calibrated in compliance with ISO 10 012:2003(E) and ANSI/NCSL Z540-1-1994.Spectral characterization was performed using Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR)-Lumos II (Bruker OPTIK GmbH, Germany) operated by Lumos-II software.Topographically, the resulting mixture was characterized by a scanning electron microscope (SEM) (Philips XL30 ESEM).The phase images of the treated pristine and treated samples were recorded in atomic force microscopy (AFM) Nanosurf FlexAFM Liestal, Switzerland) using dynamic mode (NCLR cantilever, Tapping mode, rotation angle of 45 o , Amplitude of 1.998 V).The Raman shift of the doped film was conducted using XploRA Raman spectrometer (HORIBA Europe GmbH, Germany).The characterization was made at 785 nm wavelength which offers low fluorescence while retaining high Raman intensity.The elemental mapping of the PET-G film drop cast with pristine and ethylene glycol-treated PEDOT-PSS film was carried out using energy-dispersive X-ray spectroscopy (EDX) (XFlash 7-The New EDS Detector Series, Energy-dispersive X-ray spectrometer for electron microscopy, Carl Zeiss, Germany, the detector is from Bruker, Germany).The doping times with ethylene glycol were from 0À40 h.
The electrochemical characterizations of the films were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using Autolab PGSTAT (potentiostats-Galvanostats with Booster 20 A) (METROHM GmbH & Co. KG, Filderstadt, Germany).The stainless steel electrode was used as counter electrode and Ag/AgCl electrode as reference electrode.The measurement was performed in a three-electrode arrangement with Na 2 SO 4 electrolyte.

Electrical Performance of EG and DMSO Doped PET-G Films
Among a variety of soft electronic materials, poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT-PSS) has been one of the most often used conductive polymers for supercapacitor and related electronic devices, owing to its high electrical conductivity, good optical transparency, stretchability, and decent electromechanical properties. [34]In this work, the electrical performance of doped films was measured at the center of the films, as shown in the profile (Figure 2).
The measurement was conducted based on the machine manual instruction.
Here, the conductivity (S m À1 ) and the sheet resistance of the center (ohm square À1 ) was measured.Considering the center value is the highest conductivity and the lowest sheet resistance of the sample than that of the edge region (drop casting has a probability of higher concentration at the center), the center suits the main region of study.The film prepared by 133.33  .69E À05 AE 1.764 E À07 ohm/ squares for EG and DMSO doping, respectively.The conductivity of pure PEDOT-PSS is only ≈1 S cm À1 according to the supplier information.Doping of PEDOT-PSS continued until 62 h.For each method, three samples were prepared and the average reported.However, at these times, the PEDOT-PSS changed into solids and was not able to be drop cast on PET-G.This could be attributed to the removal of hydrophilic PSS which reduces the dispersion ability of PEDOT.We elucidate the mechanism of electrical conductivity enhancement at the molecular level, demonstrating that DMSO softens the PSS to leave the conductive PEDOT in the core for self-aggregation, leading to subsequent phase separation of PEDOT and PSS by charge screening. [35]thylene glycol and dimethyl sulfoxide can produce chemical changes on the PEDOT-PSS film.Doping of PEDOT-PSS with these chemicals possesses a phase segregated morphology. [36]his would bring separate PEDOT-rich films which can be surrounded by a shell of PSS pushed out from the inside grain due to chemical doping.This means PSS hydrophilic and insulative PSS lamellas would be expulsed to the outer shell.Consequently, the conductivity was enhanced.Therefore, with this high conductivity, the materials can function as an electrode material for supercapacitor fabrication.

Structural and Morphological Characteristics of EG/DMSO:PEDOT-PSS
The functional groups of PEDOT-PSS doped using liquids were characterized by FTIR, as shown in Figure 3.The peaks between 2800 and 3000 cm À1 corresponding to the CÀH stretching of PEDOT and PSS result from the PEDOT-PSS structure. [37]he peaks between 2000 and 2400 cm À1 (Figure 3c) do not associate with any bands.This needs further exploration.The peaks at 1641 and ≈1510 cm À1 are attributed to C═C stretching of PSS and PEDOT, respectively. [37]The peaks at ≈1300 cm À1 might be attributed to C─C stretching of PEDOT. [37]The two peaks between 1100 and 2000 cm À1 correspond to S─O stretching of PSS and C─O stretching of PEDOT, respectively. [38]The two peaks between 1000 and 1100 cm À1 correspond to C─O stretching of PEDOT and S═O starching of PSS. [38]The peaks between 700 and 1000 cm À1 are attributed to C─S stretching of thiophene ring PEDOT. [39]s shown in Figure 3, there is a great distinction in the treatment of PEDOT-PSS using dimethyl sulfoxide and ethylene glycol.This could be attributed to the removal of PSS on the surface due to liquids. [29,34]For instance, the peak at 1641 cm À1 , which is attributed to C═C stretching in the aromatic ring of PSS, is reduced.The symmetric and asymmetric stretching of S═O between 1000 and 1100 cm À1 is reduced (Figure 3a,b) when treated with DMSO and EG.The large peaks observed between 1000 and 1100 cm À1 are believed to be the intensity of C─O stretching of PEDOT, which increases due to the removal of S═O stretching of PSS.
Figure 4 shows the morphological structure of PEDOT-PSS analyzed by SEM. Figure 4a shows the surface of pristine PEDOT-PSS on oxygen plasma-treated PET-G.As shown in Figure 4, the untreated one shows a clear image of PEDOT-PSS, which shows the even distribution of conductive polymers.
Figure 4b-d shows that the partial removal of PSS due to the cosolvent doping of PEDOT-PSS resulted in the washing away of PSS due to EG and DMSO treatment. [40]The micrographs of both samples showed smooth and homogenous morphology.The uniform wetting was assisted by oxygen plasma surface modification.The micrographs treated with ethylene glycol and dimethyl sulfoxide reveal that the grains are separated by marginal distances with enough binding energy to form a percolating network.The addition of PEDOT-PSS onto EG and DMSO directs the formation of small grains, which are interconnected to each other and help to transfer charges.The PEDOT-PSS SEM analysis reveals a smooth surface with micrograins developing in the polymer matrix and a good capacity for film production.
AFM was used to examine the phase and topography of the of PEDOT-PSS films in various liquid treatments, as shown in Figure 5. Compared with the pristine PEDOT-PSS, the treatment of PEDOT-PSS with EG and DMSO results in increased phase separation between the PEDOT-rich area (bright color) and the PSS-rich area (dark color).
The treatment of PEDOT-PSS with liquids for more than 40 h leads to excessive aggregation of PEDOT-PSS and turns into fragile solids.It can be observed from the phase images (Figure 5b, d,f ) that as PEDOT-PSS is treated by liquids, it clearly revealed that PEDOT grains and PSS segments in pristine sample progressively develop masks, signifying that phase separation might occur between conductive PEDOT and hydrophilic and insulative PSS layer in liquid-treated samples.After liquid   treatment, the inclusive PSS segment partially moved to the outer surface. [29]This leads to an increase in the conductivity of the film as the insulative layer hinders the charge transport.
In addition, the removal of nonconductive PSS-rich domains was confirmed by Raman spectroscopy measurement.As shown in Figure 6, the spectrum of PEDOT-PSS structure possesses four PEDOT and PSS bands, on which some of them are strong and the others are weak bands.PEDOT exhibits at 1524 cm À1 (C α ═C β , stretching), 1452 cm À1 (C β ÀC β , stretching), 1383 cm À1 (C β ÀC β ), and 1272 cm À1 (C α ÀC α , stretching).Similarly, PSS exhibits peaks at 1095, 1258, and 1572 cm À1 . [41]s a consequence of solution doping, there is a high reduction in the intensity of PEDOT at 1524 cm À1 , which could probably be the change of the benzoide structure to quinoid structure of PEDOT. [42]The intensity of PSS is highly reduced for both liquid treatments due to the removal of PSS polymers. [43]It is a proven fact that ethylene glycol and dimethyl sulfoxide can remove excess water and reduce the insulating effects of residual PSS (the polyelectrolyte component) in the film.The change in the intensity of the PEDOT-PSS after doping with ethylene glycol and dimethyl sulfoxide shows the rearrangement and removal of PSS chain outside the surface of the whole chain. [4]SS does not produce a significant Raman peak because of the conjugated double band.Raman spectroscopy is not appropriate for characterizing PEDOT-to-PSS ratios.To investigate the effects of solvents on the PEDOT-to-PSS ratios, EDX elemental mapping measurements were performed with an acceleration voltage of 3 kV.Figure 7 shows the EDX.PEDOT-PSS presents two distinct sulfur groups corresponding to thiophene ring from PEDOT and sulfonate group from PSS. [44] The EDX spectrum of PET-G film drop cast with pristine and ethylene glycol-doped PEDOT-PSS is shown in Figure 7.
The elemental analysis of composite sample through EDX shows the presence of signals resulting from C, S, and O, confirming the presence of PEDOT-PSS, and the spectra of the PET-G film strongly confirm the uniform distribution of the PEDOT-PSS film.The traceable sodium (Na) most likely stem from the catalyst during the fabrication process of Clevios P. [45] The PEDOT-PSS is specified by two distinct types of sulfur atoms in the thiophene unit in PEDOT (≈100 eV) and sulfonate (SO 3 H) groups of PSS (≈2.25 keV).The sulfur concentration of the pristine PEDOT-PSS is 24.45 AE 2.15 while the concentration of sulfur after treating PEDOT-PSS with ethylene glycol for 48 h is 17.65 AE 0.09.The decrease in the concentration was found to be 31.902%.The ratio of sulfur in pristine and ethylene glycol-doped PEDOT-PSS was found to be 1.39.The doping of PEDOT-PSS leads to the successful removal of PSS solution.This result is consistent with the work reported by Jin, I.S. et al. [46] using X-ray photoelectron spectroscopy when treated with dimethyl sulfoxide.Moreover, the decrease in the concentration of sulfur seems to be enhanced by ethylene glycol treatment. [47]A consequence of small grains of PSS and large grains of PEDOT of the solution would promote the high conductivity of the film produced out of it.

Electrochemical Characteristics of EG/DMSO:PEDOT-PSS
The electrochemical properties of conductive PET-G films were investigated using a three-electrode configuration.The obtained leaf-shaped CV curves of ethylene glycol-treated PEDOT-PSS/ PET-G (Figure 8a) are shown with quasirectangular triangular/ leaf-shaped CV curves of DMSO-treated PEDOT-PSS/PET-G film (Figure 8b).The measurement was conducted in 1 M Na 2 SO 4 electrolyte solution (at a scan rate range of 5À100 mV s À1 , the voltage window of À0.5 to 0 V).The results for EG/PEDOT-PSS/PET-G show a visual confirmation of the capacitance behavior.While the CV curve for pristine sample shows deformed leaf shape, the CV plot at 5 mV s À1 has a large area.The value of the specific capacitance at 5 mV s À1 was found to be 379.80F g À1 , which is extremely high at low scan rate.This indicates that the ions in the electrolyte travel at an exceptionally low rate.The specific capacitance was projected from the CV curve according to the following equation.
where ∫ idV is the integrated absolute area in the CV curve, i and dV denote the instantaneous current and differential potential in CV curve, respectively, k is the scan rate, m represents the mass of the active material, and ΔV is the potential window.When we estimate the capacitance from CV curve, we consider only the discharging part.We assume that charging and discharging contribute the same amount of charge, so we must divide the area by 2 when calculating specific capacitance.In this experiment, we applied neutral electrolyte due to the fact that neutral electrolyte exhibits much higher ionic conductivities when compared to other aqueous (alkaline and acidic) electrolytes. [48]he capacitance behavior of the electrodes fabricated using DMSO:PEDOT-PSS/PET-G shows the configuration of electronic double-layer capacitance (EDLC) with quasirectangular/ trapezoidal shape.The maximum specific capacitance for EG treated obtained at 5 mV s À1 was calculated to be 134 F g À1 .The specific capacitance for DMSO-treated sample is 309.6 at 20 mV s À1 , while the specific capacitance for pristine PEDOT-PSS calculated at 80 mV s À1 was 4.60 F g À1 .As the ions in the electrolyte travel rapidly, the capacitance reduces for both electrodes.When there is a redox reaction in conjugated PEDOT-PSS polymer film, there might be a probability of EDLC-type supercapacitors. [49]However, PEDOT-PSS supercapacitors showed pure pseudocapacitors, [50] while still a mixture type is possible. [28]his may be attributed to low interfacial resistance at lowfrequency regions. [51]When PEDOT-PSS is treated with DMSO, it shows a Faradaic redox reaction and non-Faradaic capacitance due to the redox activity of PEDOT-PSS and large surface area. [52]he above results showed that the response of the PEDOT-PSS electrode to redox reactions is so quick and its resistance is rather low [53] which is consistent with the previous reports on the conductive polymer-based supercapacitors.It is obviously observed that PEDOT-PSS/EG/DMSO showed a difference to that of the pristine one which showed that doping with EG/DMSO has a strong influence on the capacitive performance of the device with visible increase in the specific capacitance and hence supercapacitive performance.The cyclic voltammograms showed a quasirectangular shape (Figure 8c) treated with DMSO which showed similar findings with the previous study. [54]urther studies were conducted to investigate the supercapacitor performance using EIS analysis in the frequency range from 1 E þ5 Hz to 0.1 Hz (Figure 9).The Nyquist plot of real impedance (Z') versus imaginary impedance (ÀZ") for PET-G film electrode in Na 2 SO 4 electrolyte is shown in Figure 9.In the high-frequency range, two half semicircles and the capacitive behavior of PEDOT-PSS-based electrodes [55] are shown.The low impedance values of 2.91 and 2.28 Ω at 10 5 Hz, for EG and DMSO treated, respectively, show an excellent conductivity of PEDOT-PSS-based films and good access of Na 2 SO 4 electrolyte.The absence of semicircles in the low-frequency range in Nyquist plot or the smaller value of charge transfer resistance exhibit high conductivity of the electrode during the reaction with Na 2 SO 4 electrolyte.
Even though the Nyquist plot seems to have half semicircles at high-frequency ranges, it shows almost a vertical plot at the lowfrequency region where electrodes are dominated by purely capacitive behavior. [56]he typical circuit fit includes the solution resistance (R s ), the polarization resistance (R p ), Warburg impedance (W), tangent hyperbolic (T), and constant phase element (CPE).Solution resistance, R s , refers to the resistance between a solution containing ions at a certain concentration and an electrochemical cell.R p refers to the resistance that causes current to flow due to the electrochemical reactions it induces at the electrode surface.Furthermore, W indicates the resistance of electrons due to the diffusion interface between the bulk solution and the electrode interface and CPE refers to is a capacitive element with a frequency-independent negative phase between current and voltage which interpolates between a capacitor and a resistor. [57]he influence of Warburg impedance is very low as there is observed a straight line in the lower-frequency region. [57]

Conclusion
In conclusion, this report presents the utilization of dropcast PET-G:PEDOT-PSS film electrodes for supercapacitor  applications.Oxygen plasma surface-modified PET-G films were used as substrates to prepare EG/DMSO-doped PEDOT-PSS electrodes by drop casting.Electrical conductivity measurement confirms an average conductivity of 11661.672and 11528.764S m À1 for EG and DMSO-treated PEDOT-PSS film, respectively.However, the pristine PEDOT-PSS film exhibits ≈1 S cm À1 .Innovative doping technique unleashes superconductivity in PEDOT-PSS films for supercapacitors.From CV measurements, the specific capacitance found to be 134 F g À1 at 5 mV s À1 scan rate and 309.6 F g À1 at 20 mV s À1 scan rate for EG and DMSO-treated PEDOT-PSS films, respectively, using the three-electrode system.PEDOT-PSS films achieved unparalleled supercapacitor performance via spontaneous liquid wicking.Raman spectroscopy and FTIR results confirm the removal of PSS due to EG and DMSO additions.Our strategy offers a promising avenue for enhancing the functional properties of these flexible substrates.The versatile and efficient PET-G:PEDOT-PSS conducting polymer emerges as a compelling material with applications spanning various domains, owing to its elevated electrical conductivity, superb mechanical flexibility, and straightforward processing.Employing the drop-casting technique enhances the electrical conductivity of PET-G films, rendering them well-suited for applications demanding conductivity, such as flexible electronics, sensors, and electrodes.Additionally, the PET-G films benefit from a uniform and firmly adherent PEDOT-PSS layer, creating a robust barrier that shields the substrate from environmental influences and augments overall durability.The synergy between PEDOT-PSS and PET-G presents innovative prospects in the arenas of smart materials, wearable electronics, and advanced functional coatings.As a result, this hybrid material system holds enormous potential in the various industries, including healthcare, automotive, aerospace, and consumer electronics.In conclusion, the coating of PEDOT-PSS on PET-G films represents a significant advancement in the field of functional materials and promises to revolutionize numerous industries by enabling the development of innovative and cutting-edge technologies.As researchers continue to explore and refine this material system, we can look forward to witnessing its widespread adoption and impact soon.

Figure 1 .
Figure 1.Schematic view of spontaneous a) doping with ethylene glycol and dimethyl sulfoxide and b) ethylene glycol-doped PEDOT (black domains)-PSS (blue domains) after 28 days.c) Oxygen plasma treatment d) drop cast of PEDOT-PSS on PET-G films.e) PEDOT-PSS during treatment (doping), f ) PEDOT-PSS after doping (the nonconductive PSS polymer moved toward the outside periphery due to the reaction of chemicals with doping agents,[29,58] g) drying of the coated film at 55 °C, h) dried film, and i) characterization of the conductive films using impedance spectroscopy.
cm À2 (400 μL EG and DMSO-doped PEDOT-PSS were drop cast on a 20 mm Â 15 mm PET-G area with a volume ratio of PEDOT-PSS to EG /DMSO of 4:10 and the treatment/doping time of 2, 16, 28, and 40 h for each liquid).After adding PEDOT-PSS on a liquid drop wise, the solution was kept for the said time at fume hood.The samples treated for 40 h exhibited the highest electrical conductivity of 11661.672AE 25.546 and 11528.764AE 23.201 S m À1 , the lowest sheet resistance of 8.578 E À05 AE 1.836 E À07 , and 8

Figure 5 .
Figure 5. AFM images of films prepared by a,b) topography and phase-forward images of films drop cast with pristine PEDOT-PSS.c,d) Topography and phase-forward images of films drop cast with ethylene glycol-treated PEDOT-PSS.e,f ) Topography and phase-forward images of films drop cast with DMSO-treated PEDOT-PSS.The PEDOT-PSS-to-liquid ratio was 4:10 drop cast on a 20 mm Â 15 mm oxygen plasma-modified PET-G substrate films.The PEDOT-PSS was doped for 40 h.

Figure 6 .
Figure 6.Raman spectra of PEDOT-PSS thin films drop cast on PET-G after doping with ethylene glycol and dimethyl sulfoxide for 40 h.

Figure 7 .
Figure 7.Comparison of EDX spectrum of the PET-G film drop cast with a) pristine PEDOT-PSS and b) ethylene glycol-doped PEDOT-PSS.

Figure 8 .
Figure 8. CV curves for PEDOT-PSS-coated PET-G films: a) pristine b) treated with ethylene glycol and c) treated with dimethyl sulfoxide.

Figure 9 .
Figure 9. EIS (Nyquist plot) graph of PET-G electrode drop cast using a) EG and DMSO-treated PEDOT-PSS.b) EIS circuit fit for EG and DMSO-treated PEDOT-PSS at an amplitude of 30 mV RMS .The treatment time both liquids is 40 h.