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Characterisation of buried conjugated polymer interfaces by off specular neutron scattering. / David William James

Swansea University Author: David William James

Abstract

Neutron reflectivity offers the opportunity for non-destructive characterisation of buried polymer interfaces. Specular neutron reflectivity is commonly used to characterise the structure of conjugated polymer interfaces found in organic electronic devices. However, detecting specularly reflected ne...

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Published: 2011
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42678
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spelling 2018-08-02T16:24:30.0866121 v2 42678 2018-08-02 Characterisation of buried conjugated polymer interfaces by off specular neutron scattering. f01226e7bc38b22b9593e27545f674b4 NULL David William James David William James true true 2018-08-02 Neutron reflectivity offers the opportunity for non-destructive characterisation of buried polymer interfaces. Specular neutron reflectivity is commonly used to characterise the structure of conjugated polymer interfaces found in organic electronic devices. However, detecting specularly reflected neutrons only allows the measurement of the root-mean-square (RMS) roughness of the interface averaged over a macroscopic lateral distance. There are two contributions to the RMS roughness of a polymer/polymer interface; i) the so-called 'intrinsic interfacial width' due to mixing of the polymers at a molecular level and ii) lateral roughness due to deviations of the interface position from the plane of the substrate. In this work a numerical model is developed to analyse experimental off specular reflectivity. The model is based on the distorted wave Born approximation (DWBA). Specular and off specular neutron reflectivity data is collected from a model conjugated polymer/amorphous polymer interface (poly(9,9-dioctylfluorene) (F8) on deuterated PMMA) and a conjugated poly- mer/fullerene interface (poly(3-hexylthiophene) (P3HT) polymer on [6,6]-phenyl C61-butyric acid methylester (PCBM)). This allows probing of the structure in the plane of the interfaces to distinguish the intrinsic interfacial width from the lateral roughness. The structure of the F8/dPMMA interface is studied by systematically varying the film thickness, which strongly impacts on the amplitude of the lateral interface roughness, and allows more complete analysis of the relative contributions of intrinsic mixing and lateral roughness. For comparison off specular measurements on amorphous/amorphous polymer (PMMA/polystyrene) interfaces are performed, which have been studied previously using specular neutron reflectivity and self consistent held theory. Fitting specular reflectivity using standard techniques and off specular reflectivity data using the model developed allow intrinsic and lateral roughness contributions for the F8/dPMMA system to be separated by direct measurement. The P3HT/PCBM interface exhibits no lateral roughness as the materials are found to be miscible. E-Thesis Computational physics.;Applied physics.;Nuclear physics and radiation. 31 12 2011 2011-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:30.0866121 2018-08-02T16:24:30.0866121 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised David William James NULL 1 0042678-02082018162513.pdf 10807447.pdf 2018-08-02T16:25:13.3930000 Output 28724561 application/pdf E-Thesis true 2018-08-02T16:25:13.3930000 false
title Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
spellingShingle Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
David William James
title_short Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
title_full Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
title_fullStr Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
title_full_unstemmed Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
title_sort Characterisation of buried conjugated polymer interfaces by off specular neutron scattering.
author_id_str_mv f01226e7bc38b22b9593e27545f674b4
author_id_fullname_str_mv f01226e7bc38b22b9593e27545f674b4_***_David William James
author David William James
author2 David William James
format E-Thesis
publishDate 2011
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description Neutron reflectivity offers the opportunity for non-destructive characterisation of buried polymer interfaces. Specular neutron reflectivity is commonly used to characterise the structure of conjugated polymer interfaces found in organic electronic devices. However, detecting specularly reflected neutrons only allows the measurement of the root-mean-square (RMS) roughness of the interface averaged over a macroscopic lateral distance. There are two contributions to the RMS roughness of a polymer/polymer interface; i) the so-called 'intrinsic interfacial width' due to mixing of the polymers at a molecular level and ii) lateral roughness due to deviations of the interface position from the plane of the substrate. In this work a numerical model is developed to analyse experimental off specular reflectivity. The model is based on the distorted wave Born approximation (DWBA). Specular and off specular neutron reflectivity data is collected from a model conjugated polymer/amorphous polymer interface (poly(9,9-dioctylfluorene) (F8) on deuterated PMMA) and a conjugated poly- mer/fullerene interface (poly(3-hexylthiophene) (P3HT) polymer on [6,6]-phenyl C61-butyric acid methylester (PCBM)). This allows probing of the structure in the plane of the interfaces to distinguish the intrinsic interfacial width from the lateral roughness. The structure of the F8/dPMMA interface is studied by systematically varying the film thickness, which strongly impacts on the amplitude of the lateral interface roughness, and allows more complete analysis of the relative contributions of intrinsic mixing and lateral roughness. For comparison off specular measurements on amorphous/amorphous polymer (PMMA/polystyrene) interfaces are performed, which have been studied previously using specular neutron reflectivity and self consistent held theory. Fitting specular reflectivity using standard techniques and off specular reflectivity data using the model developed allow intrinsic and lateral roughness contributions for the F8/dPMMA system to be separated by direct measurement. The P3HT/PCBM interface exhibits no lateral roughness as the materials are found to be miscible.
published_date 2011-12-31T03:53:26Z
_version_ 1763752653820526592
score 11.016906

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