AUTHOR=Zhu Qiang , Yildirim Erol , Wang Xizu , Soo Xiang Yun Debbie , Zheng Yun , Tan Teck Leong , Wu Gang , Yang Shuo-Wang , Xu Jianwei 

TITLE=Improved Alignment of PEDOT:PSS Induced by in-situ Crystallization of “Green” Dimethylsulfone Molecules to Enhance the Polymer Thermoelectric Performance

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00783

DOI=10.3389/fchem.2019.00783

ISSN=2296-2646

ABSTRACT=<p>Dimethylsulfone (DMSO<sub>2</sub>), a small organic molecule, was observed to induce the alignment of poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) via <italic>in-situ</italic> crystallization in PEDOT:PSS mixture, which was verified by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). A chemically stable dopant, DMSO<sub>2</sub>, remarkably raised the electrical conductivity of the PEDOT:PSS film, which was fabricated from pre-mixed solution of PEDOT:PSS and DMSO<sub>2</sub>, up to 1080 S/cm, and more importantly, such a PEDOT:PSS film showed a long-term humidity stability and it retained near 90% electric conductivity after 60 days, suggesting DMSO<sub>2</sub> is promising for an eco-friendly alternative to replace dimethyl sulfoxide (DMSO), ethylene glycol (EG) and various acids dopants that have been widely employed to dope and post-treat PEDOT:PSS. Pairwise interaction energies and free energy of solvation between PEDOT:PSS and DMSO<sub>2</sub> were calculated by first-principles and molecular mechanics, respectively, revealing the mechanism of DMSO<sub>2</sub> in enhancing the electrical conductivity.</p>