Concept of the time-dependent diffusion coefficient of polarons in organic semiconductors and its determination from time-resolved spectroscopy

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389013%3A_____%2F18%3A00494710" target="_blank" >RIV/61389013:_____/18:00494710 - isvavai.cz</a>

Result on the web

<a href="http://dx.doi.org/10.1021/acs.jpcc.8b07395" target="_blank" >http://dx.doi.org/10.1021/acs.jpcc.8b07395</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpcc.8b07395" target="_blank" >10.1021/acs.jpcc.8b07395</a>

Result language

angličtina

Original language name

Concept of the time-dependent diffusion coefficient of polarons in organic semiconductors and its determination from time-resolved spectroscopy

Original language description

The population of photogenerated species in organic semiconductors may decay due to their mutual annihilation upon collisions during their diffusive motion. The standard kinetic models for the population decay, n(t), assume a time-invariant diffusion coefficient, i.e., D(t) ≡ constant. This leads to a failure in predicting the experimentally observed temporal evolution of photogenerated species if it asymptotically approaches a power-law decay n(t) ∼ t–x, with x < 0.5. We have used a concept of the time-dependent diffusion coefficient and developed a novel mathematical method of its determination from decay collision rates obtained by transient optical absorption spectroscopy. We tested the applicability of this method on the interpretation of data of the decay of polaron population obtained experimentally by time-resolved transient absorption measurements on thin films of regioregular poly(3-hexylthiophene), where we recently reported a power-law asymptote with x = 0.24. While we do not assume any microscopic origin of the time variance of D(t), we argue that, as the charge-carrier trapping states occupancy drops with decaying charge concentration, the carrier motion slows down. This argument is supported by a recent report on a molecular-scale model taking into account significant local anisotropy present in linear conjugated polymers. Our concept can be applied for the description of the evolution of species, like polarons or excitons, in various organic materials, provided their decay kinetics is controlled by a mutual annihilation during one- or three-dimensional diffusion.

Czech name

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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

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2018

Confidentiality

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

Name of the periodical

Journal of Physical Chemistry C

ISSN

1932-7447

e-ISSN

—

Volume of the periodical

122

Issue of the periodical within the volume

40

Country of publishing house

US - UNITED STATES

Number of pages

8

Pages from-to

22876-22883

UT code for WoS article

000447471700008

EID of the result in the Scopus database

2-s2.0-85054401200