The impact of solvent doping on the morphology and performance of spray-coated PEDOT:dPSS: A USANS and SANS study

Thusitha Etampawala; Mehran Tehrani; Ali Nematollahi; Lilin He; Mark Dadmun

doi:10.1016/j.orgel.2017.08.030

The impact of solvent doping on the morphology and performance of spray-coated PEDOT:dPSS: A USANS and SANS study

Thusitha Etampawala, Mehran Tehrani, Ali Nematollahi, Lilin He, Mark Dadmun

Large Scale Structures

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Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is used in a broad range of organic electronics devices, where their performance can be dramatically enhanced by solvent processing. The morphological changes that occur with solvent processing, as well as the impact of deposition technique, are not well understood, but this understanding is crucial to rationally tune the performance of PEDOT:PSS. In this study, the change in the morphology and conductivity of spray-coated PEDOT:PSS films with pre- and post-deposition processing in the presence of polar solvents is investigated by means of neutron scattering. Deuterium labeling of PSS is used to distinguish between the PEDOT and PSS phases. Changes in the morphology of PEDOT:deuterated PSS (PEDOT:dPSS) films with the addition of 5% dimethyl sulfoxide (DMSO) to the pre-deposition PEDOT:dPSS solutions enhances the conductivity by ca. 60-fold, and is further enhanced by ca. 2-fold by soaking the films in ethylene glycol (EG). Neutron scattering reveals that the morphology of the spray-coated PEDOT:dPSS film consists of a two-phase structure on the micron to nanometer length scales, where more locally ordered PEDOT-rich fibril-like domains are dispersed on the smallest length scale. Upon DMSO addition, the PEDOT:dPSS domain sizes decrease dramatically. However, with soaking in EG, the sizes of the local domains increase isotropically. Thus, the enhanced electrical conductivity of the spray-coated PEDOT:dPSS with solvent doping is dominated by morphological changes, and not changes in the PEDOT:dPPS composition in these spray-coated films.

Original language	English
Pages (from-to)	86-93
Number of pages	8
Journal	Organic Electronics
Volume	51
DOIs	https://doi.org/10.1016/j.orgel.2017.08.030
State	Published - Dec 2017

Funding

The authors gratefully acknowledge the National Science Foundation ( DMR -1409034 ) for support of this project. A portion of this research was completed at ORNL's High Flux Isotope Reactor, which was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy . We also acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce , in providing the USANS facilities used in this work, where these facilities are supported in part by the National Science Foundation under Agreement No. DMR-0944772 .

Funders	Funder number
ORNL's High Flux Isotope Reactor
Scientific User Facilities Division
National Science Foundation	DMR -1409034
National Science Foundation
U.S. Department of Energy
National Institute of Standards and Technology
U.S. Department of Commerce	DMR-0944772
U.S. Department of Commerce
Basic Energy Sciences

Keywords

Neutron scattering
Organic thermoelectrics
PEDOT:PSS
Structure-property relationships

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10.1016/j.orgel.2017.08.030

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@article{9a4103cb71f94ee68d1622ce1ce93144,

title = "The impact of solvent doping on the morphology and performance of spray-coated PEDOT:dPSS: A USANS and SANS study",

abstract = "Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is used in a broad range of organic electronics devices, where their performance can be dramatically enhanced by solvent processing. The morphological changes that occur with solvent processing, as well as the impact of deposition technique, are not well understood, but this understanding is crucial to rationally tune the performance of PEDOT:PSS. In this study, the change in the morphology and conductivity of spray-coated PEDOT:PSS films with pre- and post-deposition processing in the presence of polar solvents is investigated by means of neutron scattering. Deuterium labeling of PSS is used to distinguish between the PEDOT and PSS phases. Changes in the morphology of PEDOT:deuterated PSS (PEDOT:dPSS) films with the addition of 5% dimethyl sulfoxide (DMSO) to the pre-deposition PEDOT:dPSS solutions enhances the conductivity by ca. 60-fold, and is further enhanced by ca. 2-fold by soaking the films in ethylene glycol (EG). Neutron scattering reveals that the morphology of the spray-coated PEDOT:dPSS film consists of a two-phase structure on the micron to nanometer length scales, where more locally ordered PEDOT-rich fibril-like domains are dispersed on the smallest length scale. Upon DMSO addition, the PEDOT:dPSS domain sizes decrease dramatically. However, with soaking in EG, the sizes of the local domains increase isotropically. Thus, the enhanced electrical conductivity of the spray-coated PEDOT:dPSS with solvent doping is dominated by morphological changes, and not changes in the PEDOT:dPPS composition in these spray-coated films.",

keywords = "Neutron scattering, Organic thermoelectrics, PEDOT:PSS, Structure-property relationships",

author = "Thusitha Etampawala and Mehran Tehrani and Ali Nematollahi and Lilin He and Mark Dadmun",

note = "Publisher Copyright: {\textcopyright} 2017 Elsevier B.V.",

year = "2017",

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doi = "10.1016/j.orgel.2017.08.030",

language = "English",

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T2 - A USANS and SANS study

AU - Etampawala, Thusitha

AU - Tehrani, Mehran

AU - Nematollahi, Ali

AU - He, Lilin

AU - Dadmun, Mark

PY - 2017/12

Y1 - 2017/12

N2 - Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is used in a broad range of organic electronics devices, where their performance can be dramatically enhanced by solvent processing. The morphological changes that occur with solvent processing, as well as the impact of deposition technique, are not well understood, but this understanding is crucial to rationally tune the performance of PEDOT:PSS. In this study, the change in the morphology and conductivity of spray-coated PEDOT:PSS films with pre- and post-deposition processing in the presence of polar solvents is investigated by means of neutron scattering. Deuterium labeling of PSS is used to distinguish between the PEDOT and PSS phases. Changes in the morphology of PEDOT:deuterated PSS (PEDOT:dPSS) films with the addition of 5% dimethyl sulfoxide (DMSO) to the pre-deposition PEDOT:dPSS solutions enhances the conductivity by ca. 60-fold, and is further enhanced by ca. 2-fold by soaking the films in ethylene glycol (EG). Neutron scattering reveals that the morphology of the spray-coated PEDOT:dPSS film consists of a two-phase structure on the micron to nanometer length scales, where more locally ordered PEDOT-rich fibril-like domains are dispersed on the smallest length scale. Upon DMSO addition, the PEDOT:dPSS domain sizes decrease dramatically. However, with soaking in EG, the sizes of the local domains increase isotropically. Thus, the enhanced electrical conductivity of the spray-coated PEDOT:dPSS with solvent doping is dominated by morphological changes, and not changes in the PEDOT:dPPS composition in these spray-coated films.

AB - Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is used in a broad range of organic electronics devices, where their performance can be dramatically enhanced by solvent processing. The morphological changes that occur with solvent processing, as well as the impact of deposition technique, are not well understood, but this understanding is crucial to rationally tune the performance of PEDOT:PSS. In this study, the change in the morphology and conductivity of spray-coated PEDOT:PSS films with pre- and post-deposition processing in the presence of polar solvents is investigated by means of neutron scattering. Deuterium labeling of PSS is used to distinguish between the PEDOT and PSS phases. Changes in the morphology of PEDOT:deuterated PSS (PEDOT:dPSS) films with the addition of 5% dimethyl sulfoxide (DMSO) to the pre-deposition PEDOT:dPSS solutions enhances the conductivity by ca. 60-fold, and is further enhanced by ca. 2-fold by soaking the films in ethylene glycol (EG). Neutron scattering reveals that the morphology of the spray-coated PEDOT:dPSS film consists of a two-phase structure on the micron to nanometer length scales, where more locally ordered PEDOT-rich fibril-like domains are dispersed on the smallest length scale. Upon DMSO addition, the PEDOT:dPSS domain sizes decrease dramatically. However, with soaking in EG, the sizes of the local domains increase isotropically. Thus, the enhanced electrical conductivity of the spray-coated PEDOT:dPSS with solvent doping is dominated by morphological changes, and not changes in the PEDOT:dPPS composition in these spray-coated films.

KW - Neutron scattering

KW - Organic thermoelectrics

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KW - Structure-property relationships

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DO - 10.1016/j.orgel.2017.08.030

M3 - Article

AN - SCOPUS:85029432832

SN - 1566-1199

VL - 51

SP - 86

EP - 93

JO - Organic Electronics

JF - Organic Electronics

ER -

The impact of solvent doping on the morphology and performance of spray-coated PEDOT:dPSS: A USANS and SANS study

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