Analysis of the Physical Origin of the Red-Shift of Absorption Peaks of Conjugated Polymers in Solution

doi:10.19894/j.issn.1000-0518.210138

Chinese Journal of Applied Chemistry ›› 2021, Vol. 38 ›› Issue (11): 1486-1493.DOI: 10.19894/j.issn.1000-0518.210138

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Analysis of the Physical Origin of the Red-Shift of Absorption Peaks of Conjugated Polymers in Solution

HUANG Jie-Tao^1,2, WANG Da-Peng^1,2*

¹State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;
²University of Science and Technology of China, Hefei 230026, China

Received:2021-03-23 Accepted:2021-06-04 Published:2021-11-01 Online:2022-01-01

Abstract

Abstract: Fluorescence correlation spectroscopy (FCS) was used to measure the hydrodynamic radius (R_H) of two classic conjugated polymers (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene, MEH-PPV and poly(3-hexylthiophene), P3HT) in different solvents. It is found that the R_H of the two polymers in various solvents is linear with the maximum absorption wavelength (λ_max) for the same polymer. We construct a mixed solvent system using good and bad solvents, and investigate the relationship between R_H and λ_max for MEH-PPV in a specific solvent mass by regulating the volume fraction of bad solvents. It is investigated that R_H and λ_max show a linear relationship in the presence of aggregation and conformational collapse. Furthermore, we study the absorption spectra and corresponding R_H of MEH-PPV oligomers containing only four repeating units in a tetrahydrofuran-pure water mixture, and the λ_max still remains red-shifted with increasing the proportion of non-solvent water. According to the above research work, it can be known that the absorption maximum for conjugated polymers in dilute solution is associated with the hydrodynamic radii of individual fluorophores that can be made of either the single-chain polymer or the polymer aggregate.

Key words: Conjugated polymer, Fluorescence correlation spectroscopy, Ultraviolet spectroscopy, Hydrodynamic radius

CLC Number:

O631.2

HUANG Jie-Tao, WANG Da-Peng. Analysis of the Physical Origin of the Red-Shift of Absorption Peaks of Conjugated Polymers in Solution[J]. Chinese Journal of Applied Chemistry, 2021, 38(11): 1486-1493.

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Analysis of the Physical Origin of the Red-Shift of Absorption Peaks of Conjugated Polymers in Solution

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