Dependence of Exciton Binding Energy on Bandgap of Organic Semiconductors

Strongly bound excitons crucially affect the operation of organic optoelectronic devices. Nevertheless, precise experimental data on the exciton binding energy of organic semiconductors are lacking. In this study, we determine the exciton binding energy as the difference between the optical and transport bandgaps with a precision of 0.1 eV. In particular, electron affinities with a precision higher than 0.05 eV determined by low-energy inverse photoelectron spectroscopy allow us to determine the transport gap and the exciton binding energies with such high precision. Through a systematic comparison of a wide range of organic semiconductors, including 42 organic solar cell materials (15 nonfullerene acceptors, 4 fullerene acceptors, 13 low-bandgap polymers, 7 organic light-emitting diode materials, and 3 crystalline materials), we found that the exciton binding energy is one-quarter of the transport gap regardless of the materials. We interpret this unexpected relation from a hydrogen atom-like model, i.e., the quantized energy levels in a Coulomb potential between the positive and the negative charges.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:14

Enthalten in:

The journal of physical chemistry letters - 14(2023), 50 vom: 21. Dez., Seite 11412-11420

Sprache:

Englisch

Beteiligte Personen:

Sugie, Ai [VerfasserIn]
Nakano, Kyohei [VerfasserIn]
Tajima, Keisuke [VerfasserIn]
Osaka, Itaru [VerfasserIn]
Yoshida, Hiroyuki [VerfasserIn]

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Journal Article

Anmerkungen:

Date Revised 27.12.2023

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1021/acs.jpclett.3c02863

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM365723614