The enhancement of electrical and optical properties of PEDOT:PSS using one-step dynamic etching for flexible application Kyounga Lim a , Sunghoon Jung a , Seunghun Lee a , Jinhee Heo b , Juyun Park c , Jae-Wook Kang d , Yong-Cheol Kang c,⇑ , Do-Geun Kim a,⇑ a Plasma Coating Research Group, Korea Institute of Materials Science (KIMS), 797, Changwondaero, Changwon, Gyeongnam 641-831, Republic of Korea b Advanced Characterization & Analysis Research Group, Korea Institute of Materials Science (KIMS), 797, Changwondaero, Changwon, Gyeongnam 641-831, Republic of Korea c Department of Chemistry, Pukyong National University, 45, Yongso-ro, Nam-Gu, Busan 608-737, Republic of Korea d Department of Flexible and Printable Electronics, Chonbuk National University, 567, Baekje-Daero, Deokjin-Gu, Jeonju 561-756, Republic of Korea article info Article history: Received 5 November 2013 Received in revised form 30 March 2014 Accepted 9 April 2014 Available online xxxx Keywords: Dynamic etching Conductivity enhancement PEDOT:PSS Flexible device abstract The conductivity enhancement of poly(3,4-ethylenedioxythiophene):poly(styrenesulfo- nate) (PEDOT:PSS) by dynamic etching process was investigated to introduce the outstand- ing and simplest method for soft electronics. Four different samples which were pristine PEDOT:PSS, PEDOT:PSS doped with 5 wt.% DMSO, PEDOT:PSS with dipping process, and PEDOT:PSS with dynamic etching process were prepared to compare the properties such as conductivity, morphology, relative atomic percentage, and topography. All samples were characterized by four point probe, current atomic force microscopy (C-AFM), X-ray photo- electron spectroscopy (XPS), and UV–visible spectroscopy. The conductivity of the sample with dynamic etching process showed the highest value as 1299 S/cm among four samples. We proved that the dynamic etching process is superior to remove PSS phase from PED- OT:PSS film, to flow strong current through entire surface of PEDOT:PSS, and to show the smoothest surface (RMS 2.28 nm). XPS analysis was conducted for accurate chemical and structural surface environments of four samples and the relative atomic percentage of PEDOT in the sample with dynamic etching was the highest as 29.5%. The device perfor- mance of the sample with the dynamic etching process was outstanding as 10.31 mA/cm 2 of J sc , 0.75 eV of V oc , 0.46 of FF, and 3.53% of PCE. All properties and the device performance for PEDOT:PSS film by dynamic etching process were the most excellent among the samples. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction In the late 20th century, performances of organic opto- electronic devices have rapidly progressed thereby the demand for flexible devices has intensively been on the rise these days. Indium tin oxide (ITO) is the most popular material as a transparent conductive electrode for optoelec- tronic devices because ITO has great electrical and optical properties. For flexible devices, ITO, however, has a crucial weak point in the aspect of mechanical property because ITO is easily cracked under internal and external force [1–4]. Therefore many scientists have proposed lots of materials to overcome ITO’s disadvantage such as http://dx.doi.org/10.1016/j.orgel.2014.04.014 1566-1199/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. Tel.: +82 51 629 5585; fax: +82 51 629 5584 (Y.C. Kang). Tel.: +82 55 280 3507; fax: +82 55 280 3570 (D.-G. Kim). E-mail addresses: yckang@pknu.ac.kr (Y.-C. Kang), dogeunkim@kims. re.kr (D.-G. Kim). Organic Electronics xxx (2014) xxx–xxx Contents lists available at ScienceDirect Organic Electronics journal homepage: www.elsevier.com/locate/orgel Please cite this article in press as: K. Lim et al., The enhancement of electrical and optical properties of PEDOT:PSS using one-step dynamic etching for flexible application, Org. Electron. (2014), http://dx.doi.org/10.1016/j.orgel.2014.04.014