Thickness dependence of electronic structure and optical properties of F8BT thin films

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F70883521%3A28610%2F22%3A63550958" target="_blank" >RIV/70883521:28610/22:63550958 - isvavai.cz</a>

Result on the web

<a href="https://www.mdpi.com/2073-4360/14/3/641/htm" target="_blank" >https://www.mdpi.com/2073-4360/14/3/641/htm</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/polym14030641" target="_blank" >10.3390/polym14030641</a>

Result language

angličtina

Original language name

Thickness dependence of electronic structure and optical properties of F8BT thin films

Original language 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.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10404 - Polymer science

Project

—

Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Polymers

ISSN

2073-4360

e-ISSN

—

Volume of the periodical

14

Issue of the periodical within the volume

3

Country of publishing house

CH - SWITZERLAND

Number of pages

13

Pages from-to

nestrankovano

UT code for WoS article

000754903200001

EID of the result in the Scopus database

2-s2.0-85124517590