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Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films
Electronic devices based on polymer thin films have experienced a tremendous increase in their efficiency in the last two decades. One of the critical factors that affects the efficiency of polymer solar cells or light emitting devices is the presence of structural defects that controls non-radiativ...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8838540/ https://www.ncbi.nlm.nih.gov/pubmed/35160630 http://dx.doi.org/10.3390/polym14030641 |
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author | Ghasemi, Bita Ševčík, Jakub Nádaždy, Vojtěch Végsö, Karol Šiffalovič, Peter Urbánek, Pavel Kuřitka, Ivo |
author_facet | Ghasemi, Bita Ševčík, Jakub Nádaždy, Vojtěch Végsö, Karol Šiffalovič, Peter Urbánek, Pavel Kuřitka, Ivo |
author_sort | Ghasemi, Bita |
collection | PubMed |
description | Electronic devices based on polymer thin films have experienced a tremendous increase in their efficiency in the last two decades. One of the critical factors that affects the efficiency of polymer solar cells or light emitting devices is the presence of structural defects that controls non-radiative recombination. The purpose of this report is to demonstrate a non-trivial thickness dependence of optoelectronic properties and structure (dis)order in thin conductive poly(9,9-dioctyfluorene-alt-benzothiadiazole), F8BT, polymer films. The UV-Vis absorption spectra exhibited blue shift and peak broadening; significant changes in 0–0 and 0–1 radiative transition intensity was found in photoluminescence emission spectra. The density of state (DOS) was directly mapped by energy resolved-electrochemical impedance spectroscopy (ER-EIS). Satellite states 0.5 eV below the lowest unoccupied molecular orbital (LUMO) band were revealed for the thinner polymer films. Moreover, the decreasing of the deep states density in the band gap manifested an increment in the material structural ordering with increasing thickness. Changes in the ratio between crystalline phases with face-on and edge-on orientation of F8BT chains were identified in the films by grazing-incidence wide angle X-ray scattering technique. A thickness threshold in all investigated aspects of the films at a thickness of about 100 nm was observed that can be attributed to the development of J-H aggregation in the film structure and mutual interplay between these two modes. Although a specific structure–property relationship thickness threshold value may be expected for thin films prepared from various polymers, solvents and under different process conditions, the value of about 100 nm can be generally considered as the characteristic length scale of this phenomenon. |
format | Online Article Text |
id | pubmed-8838540 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-88385402022-02-13 Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films Ghasemi, Bita Ševčík, Jakub Nádaždy, Vojtěch Végsö, Karol Šiffalovič, Peter Urbánek, Pavel Kuřitka, Ivo Polymers (Basel) Article Electronic devices based on polymer thin films have experienced a tremendous increase in their efficiency in the last two decades. One of the critical factors that affects the efficiency of polymer solar cells or light emitting devices is the presence of structural defects that controls non-radiative recombination. The purpose of this report is to demonstrate a non-trivial thickness dependence of optoelectronic properties and structure (dis)order in thin conductive poly(9,9-dioctyfluorene-alt-benzothiadiazole), F8BT, polymer films. The UV-Vis absorption spectra exhibited blue shift and peak broadening; significant changes in 0–0 and 0–1 radiative transition intensity was found in photoluminescence emission spectra. The density of state (DOS) was directly mapped by energy resolved-electrochemical impedance spectroscopy (ER-EIS). Satellite states 0.5 eV below the lowest unoccupied molecular orbital (LUMO) band were revealed for the thinner polymer films. Moreover, the decreasing of the deep states density in the band gap manifested an increment in the material structural ordering with increasing thickness. Changes in the ratio between crystalline phases with face-on and edge-on orientation of F8BT chains were identified in the films by grazing-incidence wide angle X-ray scattering technique. A thickness threshold in all investigated aspects of the films at a thickness of about 100 nm was observed that can be attributed to the development of J-H aggregation in the film structure and mutual interplay between these two modes. Although a specific structure–property relationship thickness threshold value may be expected for thin films prepared from various polymers, solvents and under different process conditions, the value of about 100 nm can be generally considered as the characteristic length scale of this phenomenon. MDPI 2022-02-08 /pmc/articles/PMC8838540/ /pubmed/35160630 http://dx.doi.org/10.3390/polym14030641 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Ghasemi, Bita Ševčík, Jakub Nádaždy, Vojtěch Végsö, Karol Šiffalovič, Peter Urbánek, Pavel Kuřitka, Ivo Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films |
title | Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films |
title_full | Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films |
title_fullStr | Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films |
title_full_unstemmed | Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films |
title_short | Thickness Dependence of Electronic Structure and Optical Properties of F8BT Thin Films |
title_sort | thickness dependence of electronic structure and optical properties of f8bt thin films |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8838540/ https://www.ncbi.nlm.nih.gov/pubmed/35160630 http://dx.doi.org/10.3390/polym14030641 |
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