Title: Is there such a thing as a molecular organic alloy?

Abstract

In inorganic materials, an alloy is a mixture of two or more substances that generally exhibits electronic and/or physical properties that differ from those of its constituents. In organic systems, the formation of a “molecular alloy” comprising mixtures of molecular organic materials has also been proposed. We test the validity of this concept via the study of the optoelectronic properties of a ternary system that has previously been identified to form a molecular acceptor alloy, namely a blend of a poly(3-hexylthiophene) (P3HT) donor, with two acceptors indene-C₆₀ bisadduct (ICBA) and phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) [R. A. Street, et al., J. Am. Chem. Soc., 2013, 135, 986–989]. Using photoelectron spectroscopy, we find that the ICBA:PC₆₁BM blend shows the same highest occupied molecular orbital and exciton energies as that of ICBA, indicating the absence of a new exciton state in the blend. Furthermore, charge transfer state spectra of ternary blends are found to comprise a simple linear superposition of the corresponding binaries. From these results, no evidence of new, emergent electronic states is found to support the existence of a molecular alloy in this system. To our knowledge there is as yet no clear evidence of the existence of an alloymore » in any organic semiconductor system. Finally, we discuss the criteria that should be met by a molecular organic alloy and procedures needed for their unambiguous identification.« less

Authors:

Huang, Xinjing ^[1]; Liu, Xiao  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-5397-6694"

Ding, Kan ^[3]; Forrest, Stephen R. ^[4]

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+ Show Author Affiliations

1. Univ. of Michigan, Ann Arbor, MI (United States). Applied Physics Program
2. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Electrical Engineering and Computer Science
3. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics
4. Univ. of Michigan, Ann Arbor, MI (United States). Applied Physics Program, Dept. of Electrical Engineering and Computer Science, Dept. of Physics, and Dept. of Materials Science and Engineering

Publication Date:

Tue Sep 10 00:00:00 EDT 2019

Research Org.:

Univ. of Michigan, Ann Arbor, MI (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1573355

Grant/Contract Number:  

EE0008561

Resource Type:

Accepted Manuscript

Journal Name:

Materials Horizons

Additional Journal Information:

Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2051-6347

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE