The authors gratefully acknowledge financial support from the US Air Force Office of Scientific Research, under agreement number FA9550-14-1-0128. T. L. A. also gratefully acknowledges partial support by the David and Lucille Packard Foundation.

Read MSDS for reagents and follow all chemical safety measures as required by your institution.
1. Deposition of Cl-PProDOT and Cl-PTT
<ol>
	<li>Build the structure of the custom-built tubular vapor deposition chamber as shown in Figure 1.
	<ol>
		<li>Make a 1/4-in. (outer diameter, O.D.) fused quartz side inlet to a 2-in. (O.D.) fused quartz tube. Make a cold trap with a custom-built U-shape 1-in. stainless-steel tube and a Dewar flask.</li>
		<li>Connect the q...

<ol>
	<li>Kaltenbrunner, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrathin+and+lightweight+organic+solar+cells+with+high+flexibility.">Ultrathin and lightweight organic solar cells with high flexibility.</a> Nat. Commun. 3, 770 (2012).</li><li>Savagatrup, S., Printz, A. D., O'Connor, T. F., Zaretski, A. V., Lipomi, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecularly+Stretchable+Electronics.">Molecularly Stretchable Electronics.</a> Chem. Mater. 26, 3028-3041 (2014).</li><li>Lee, J. -. Y., Connor, S. T., Cui, Y., Peumans, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semitransparent+Organic+Photovoltaic+Cells+with+Laminated+Top+Electrode.">Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode.</a> Nano Lett. 10, 1276-1279 (2010).</li><li>Kaltenbrunner, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+ultra-lightweight+design+for+imperceptible+plastic+electronics.">An ultra-lightweight design for imperceptible plastic electronics.</a> Nature. 499, 458-463 (2013).</li><li>Jost, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+coated+textiles+for+flexible+energy+storage.">Carbon coated textiles for flexible energy storage.</a> Energy Environ. Sci. 4, 5060-5067 (2011).</li><li>Hu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stretchable,+Porous,+and+Conductive+Energy+Textiles.">Stretchable, Porous, and Conductive Energy Textiles.</a> Nano Lett. 10, 708-714 (2010).</li><li>Jost, K., Dion, G., Gogotsi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Textile+energy+storage+in+perspective.">Textile energy storage in perspective.</a> J. Mater. Chem. A. 2, 10776-10787 (2014).</li><li>Ding, Y., Invernale, M. A., Sotzing, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conductivity+Trends+of+PEDOT-PSS+Impregnated+Fabric+and+the+Effect+of+Conductivity+on+Electrochromic+Textile.">Conductivity Trends of PEDOT-PSS Impregnated Fabric and the Effect of Conductivity on Electrochromic Textile.</a> ACS Appl. Mater. Interfaces. 2, 1588-1593 (2010).</li><li>Hong, K. H., Oh, K. W., Kang, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+properties+of+electrically+conducting+textiles+by+in+situ+polymerization+of+poly(3,4-ethylenedioxythiophene).">Preparation and properties of electrically conducting textiles by in situ polymerization of poly(3,4-ethylenedioxythiophene).</a> J. Appl. Polym. Sci. 97, 1326-1332 (2005).</li><li>Xu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabric+electrodes+coated+with+polypyrrole+nanorods+for+flexible+supercapacitor+application+prepared+via+a+reactive+self-degraded+template.">Fabric electrodes coated with polypyrrole nanorods for flexible supercapacitor application prepared via a reactive self-degraded template.</a> Org. Electron. 26, 292-299 (2015).</li><li>Du, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoelectric+Fabrics:+Toward+Power+Generating+Clothing.">Thermoelectric Fabrics: Toward Power Generating Clothing.</a> Sci. Rep. 5, 6411 (2015).</li><li>Yatvin, J., Sherman, S. A., Filocamo, S. F., Locklin, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+functionalization+of+Kevlar[registered+sign]+with+copolymers+containing+sulfonyl+nitrenes.">Direct functionalization of Kevlar[registered sign] with copolymers containing sulfonyl nitrenes.</a> Polym. Chem. 6, 3090-3097 (2015).</li><li>Musumeci, C., Hutchison, J. A., Samori, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+the+morphology+of+conductive+PEDOT+by+in+situ+electropolymerization:+from+thin+films+to+nanowires+with+variable+electrical+properties.">Controlling the morphology of conductive PEDOT by in situ electropolymerization: from thin films to nanowires with variable electrical properties.</a> Nanoscale. 5, 7756-7761 (2013).</li><li>Allison, L., Hoxie, S., Andrew, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+seamlessly-integrated+textile+electronics:+methods+to+coat+fabrics+and+fibers+with+conducting+polymers+for+electronic+applications.">Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications.</a> Chem. Commun. 53, 7182-7193 (2017).</li><li>Alf, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+Vapor+Deposition+of+Conformal,+Functional,+and+Responsive+Polymer+Films.">Chemical Vapor Deposition of Conformal, Functional, and Responsive Polymer Films.</a> Adv. Mater. 22, 1993-2027 (2010).</li><li>Goktas, H., Wang, X., Boscher, N. D., Torosian, S., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalizable+and+electrically+conductive+thin+films+formed+by+oxidative+chemical+vapor+deposition+(oCVD)+from+mixtures+of+3-thiopheneethanol+(3TE)+and+ethylene+dioxythiophene+(EDOT).">Functionalizable and electrically conductive thin films formed by oxidative chemical vapor deposition (oCVD) from mixtures of 3-thiopheneethanol (3TE) and ethylene dioxythiophene (EDOT).</a> J. Mater. Chem. C. 4, 3403-3414 (2016).</li><li>Sadki, S., Schottland, P., Brodie, N., Sabouraud, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanisms+of+pyrrole+electropolymerization.">The mechanisms of pyrrole electropolymerization.</a> Chem. Soc. Rev. 29, 283-293 (2000).</li><li>Bhattacharyya, D., Howden, R. M., Borrelli, D. C., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vapor+phase+oxidative+synthesis+of+conjugated+polymers+and+applications.">Vapor phase oxidative synthesis of conjugated polymers and applications.</a> J. Polym. Sci., Part B: Polym. Phys. 50, 1329-1351 (2012).</li><li>Yamato, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+free-standing+poly(3,4-ethylenedioxythiophene)+conducting+polymer+films+on+a+pilot+scale.">Synthesis of free-standing poly(3,4-ethylenedioxythiophene) conducting polymer films on a pilot scale.</a> Synth. Met. 83, 125-130 (1996).</li><li>Cheng, N., Zhang, L., Joon Kim, J., Andrew, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vapor+phase+organic+chemistry+to+deposit+conjugated+polymer+films+on+arbitrary+substrates.">Vapor phase organic chemistry to deposit conjugated polymer films on arbitrary substrates.</a> J. Mater. Chem. C. 5, 5787-5796 (2017).</li><li>Borrelli, D. C., Lee, S., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optoelectronic+properties+of+polythiophene+thin+films+and+organic+TFTs+fabricated+by+oxidative+chemical+vapor+deposition.">Optoelectronic properties of polythiophene thin films and organic TFTs fabricated by oxidative chemical vapor deposition.</a> J. Mater. Chem. C. 2, 7223-7231 (2014).</li><li>Jo, W. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidative+Chemical+Vapor+Deposition+of+Neutral+Hole+Transporting+Polymer+for+Enhanced+Solar+Cell+Efficiency+and+Lifetime.">Oxidative Chemical Vapor Deposition of Neutral Hole Transporting Polymer for Enhanced Solar Cell Efficiency and Lifetime.</a> Adv. Mater. 28, 6399-6404 (2016).</li><li>Wang, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CVD+Polymers+for+Devices+and+Device+Fabrication.">CVD Polymers for Devices and Device Fabrication.</a> Adv. Mater. 29, 1604606 (2017).</li><li>Kovacik, P., Hierro, G. d., Livernois, W., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scale-up+of+oCVD:+large-area+conductive+polymer+thin+films+for+next-generation+electronics.">Scale-up of oCVD: large-area conductive polymer thin films for next-generation electronics.</a> Mater. Horiz. 2, 221-227 (2015).</li><li>Barr, M. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Monolithic+Integration+of+Organic+Photovoltaic+Circuits+on+Unmodified+Paper.">Direct Monolithic Integration of Organic Photovoltaic Circuits on Unmodified Paper.</a> Adv. Mater. 23, 3500-3505 (2011).</li></ol>

The mechanism of the reaction is oxidative polymerization. Polymer coating methods using the same mechanism include electropolymerization17 and vapor phase polymerization18. Electropolymerization requires a conductive substrate, lacks the advantage of uniform and conformal coating, and is an environmentally-unfriendly solution-based method19. The existing vapor phase polymerization method is similar to the method reported here but can only polymerize...

Polymeric conducting and semiconducting materials have unique properties, such as flexibility1, stretchability2, transparency3, and low density,4 which provide extraordinary opportunities for creating next-generation electronic devices on nontraditional substrates. Currently, many researchers are endeavoring to take advantage of the unique properties of polymeric materials to create flexible and/or wearable electronics5,6 and smart textiles7. However, the ability to conformally coat highly textured surfaces and non-robust substrates, such as paper, fabrics and threads/yarns, remains unmastered. Most commonly, polymers are synthesized and coated on surfaces using solution methods.8,9,10,11,12 Although solution methods provide polymer coated fibers/textiles, the coatings thus obtained are often non-uniform and easily damaged by small physical stresses13,14 . Solution methods are also not applicable to coating paper because of wetting problems.
Reactive vapor deposition can create conformal conjugated polymer films on a diverse range of substrates, irrespective of surface chemistry/composition, surface energy and surface roughness/topography15. In this approach, conjugated polymers are synthesized in the vapor phase by simultaneously delivering monomer and oxidant vapors to a surface. Polymerization and film formation occurs on the surface in a single, solvent-free step. This method is theoretically applicable to any conjugated polymer that can be synthesized by oxidative polymerization using solution methods. However, to date, protocols for depositing only a narrow set of conjugated polymer structures are known.15
Here, we demonstrate the deposition of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and semiconducting poly(thieno[3,2-b]thiophene) (PTT) films via reactive vapor deposition. Two kinds of oxidants, solid FeCl3 and liquid Br2, are used in the process. The corresponding polymers are named Cl-PProDOT, Cl-PTT, and Br-PEDOT. Both conventional substrates, glass slides, and unconventional textured substrates, such as paper, towels and fabrics, were coated with the polymer films.
This protocol describes the setup of the custom-built vapor deposition chamber and the details of the deposition process. It is intended to help new practitioners to build their deposition system and avoid common pitfalls associated with vapor-phase synthesis.

<table>
	<tbody>
		<tr>
			<td>3,4-Ethylenedioxythiophene, 97%</td>
			<td>Sigma Aldrich</td>
			<td>483028</td>
			<td></td>
		</tr>
		<tr>
			<td>3,4-Propylenedioxythiophene, 97%</td>
			<td>Sigma Aldrich</td>
			<td>660485</td>
			<td></td>
		</tr>
		<tr>
			<td>Thieno[3,2-b]thiophene, 95%</td>
			<td>Sigma Aldrich</td>
			<td>702668</td>
			<td></td>
		</tr>
		<tr>
			<td>FeCl3, 97%</td>
			<td>Sigma Aldrich</td>
			<td>157740</td>
			<td></td>
		</tr>
		<tr>
			<td>Br2</td>
			<td>Sigma Aldrich</td>
			<td>207888</td>
			<td></td>
		</tr>
	</tbody>
</table>

reactive vapor deposition of conjugated polymer films on arbitrary substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

The thickness of Cl-PProDOT films formed on 1.3 cm x 2.5 cm glass slides placed at discrete lateral positions along the central tube were measured by a profilometer (Figure 3). Conductivities were calculated from resistivity measurements using a home-built four-point probe test station. The measured conductivity of a 100-nm thick Cl-PProDOT film on glass slides is 106 S/cm, which is sufficient to qualify this film as a potential electrode material. <strong cl...

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Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

The overall goal of this experiment is to create conformal coatings of conducting or semi-conducting polymer films on rough and textured substrates using a custom designed reactive vapor deposition chamber. This method allows soft electronic materials to be deposited on unconventional substrates to fabricate unique devices such as textile electronics. The main advantage of our chamber is that a broad section of polymers can be vapor deposited, meaning that structured diverse conjugated polymer films can be created.To begin the procedure, place 50 milligrams of ProDOT in a quartz martimer ampoule. Connect the ampoule via one fourth inch quick connect couplings and a needle valve. Wrap the ampoule, the metal parts, and the temperature probe with a heating tape.Connect the ampoule to the tubular chamber, keeping the needle valve open. Then, use long tweezers to place five 1.3 centimeter by 2.5 centimeter substrates of the desired materials adjacent to one another in the substrate heating zone. Place a five milliliter alumina crucible containing 50 milligrams of iron 3 chloride in the oxidant heating zone.Close the end of the chamber, slowly close the inert gas inlet valve, and start the vacuum pump. Once the chamber pressure is below 525 millitorrs, fill the cold trap dewar with liquid nitrogen. Wrap each of the three heating zones in heating tape.Connect the tapes to temperature controllers. When the chamber reaches the processing pressure of 52.5 millitorrs, close the martimer ampoule needle valve. Set the oxidant heater to 170 degrees Celsius, and the substrate and martimer heaters to 80 degrees Celsius.Heat at those temperatures for about ten minutes to fully vaporize the iron 3 chloride from the crucible. Confirm that vaporized iron 3 chloride is depositing as a red solid in the cool region of the tube, between the oxidant and the gas inlet before proceeding. Then, open the needle valve of the martimer ampoule, allow the blue colored thin films to grow to the desired thickness on the substrates.The needle valve to the martimer ampoules should be opened after iron chloride vapor is formed in the chamber. Otherwise, the martimer vapor will react with oxidant in the crucible to form a polymer layer around the powder surface. Close the martimer ampoule needle valve when the desired film thickness is achieved.Turn off the heating tapes, and allow the system to cool to room temperature under vacuum. Once the system has cooled, open the inert gas valve, and stop the vacuum pump. Remove the samples from the chamber using long tweezers.Immerse the samples in methanol for 30 minutes to remove residual unreacted oxidant and martimer. Handle films thicker than 500 nanometers on glass substrates with care, as they may delaminate during rinsing. When the methanol rinsing is complete, carefully dry the samples under a gentle stream of nitrogen gas.To begin the procedure, place two milliliters of EDOT in a quartz martimer ampoule. Connect the ampoule to the needle valve, and wrap them with the heating tape. Connect the ampoule to the tubular chamber, keeping the needle valve open.Next, use long tweezers to place 1.3 centimeter by 2.5 centimeter substrates adjacent to one another between the two reagent vapor inlets. Then, close the end of the chamber. In a fume hood, load two milliliters of liquid bromine into a quartz oxidant ampoule.Equip the ampoule with a closed needle valve. Connect the oxidant ampoule to the chamber via the closed needle valve. Then, start the vacuum pump with the inert gas inlet valve closed.Once the chamber pressure is below 525 millitorrs, fill the cold trap dewar with liquid nitrogen. Connect the heat tape wrapped martimer heating region to a temperature controller. When the chamber reaches the processing pressure of 52.5 millitorrs, set the martimer heater to 80 degrees Celsius.Heat at that temperature for about ten minutes to vaporize the martimer. Then, open the oxidant needle valve only slightly as liquid bromine is highly volatile. Monitor the deposition of the blue PE-DOT films so when the flims have reached their desired thickness, close the martimer and oxidant needle valves, turn off the heating tape, and allow the chamber to cool to room temperature under vacuum.Then, open the inert gas inlet valve, and stop the vacuum pump. When using bromine as the oxidant, rinsing is not needed. The maximum chlorine dubbed polyproDOT film thickness was observed at about two inches from the martimer ampoule inlet.Atomic force microscophy was used to characterize the morphology. The conductivity of a 100 nanometer thick chlorine dubbed polyproDot film was 106 siemans per centimeter. The removal of residual iron 3 chloride was confirmed with x-ray photo electron spectroscopy indicating that the conductivity is solely from the polymer.Chlorine dubbed PTT films were deposited on paper, corduroy fabric, and cotton town fabric, ultimately making the pristine white substrates appear dark red. Scanning electron microscopy indicated that the films were uniform in conformal on the three textured surfaces at a micrometer scale. UV vis spectroscopy of the chlorine dubbed polyproDot and bromine dubbed PEDOT films, showed broad featureless absorption bands beyond 600 nanometers, indicating that the films remained P-dubbed after removal of excess oxidant with methanol.This band was not observed for chlorine dubbed PTT, indicating that it was fully D-dubbed during the methanol rinse. Once mastered, this technique can be done in 2 hours, if it is performed properly. After its development, this technique allowed researchers to transform commercial fabrics and fibers into electronic components, by simply coating them with conducting or semi-conducting polymer films in our chamber.

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32.7K Views.  University of Wisconsin-Madison. The overall goal of this experiment is to create conformal coatings of conducting or semi-conducting polymer films on rough and textured substrates using a custom designed reactive vapor deposition chamber. This method allows soft electronic materials to be deposited on unconventional substrates to fabricate unique devices such as textile electronics. The main advantage of our chamber is that a broad section of polymers can be vapor deposited, meaning that structured diverse conjugated polyme...