Abstract

The dipole characteristics of Frenkel excitons and charge-transfer excitons between donor and acceptor molecules in organic heterostructures such as exciplexes are important in organic photonics and optoelectronics. For the bilayer of the organic donor 4,4′,4′′-tris[(3-methylphenyl)phenylamino]triphenylamine and acceptor 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine molecules, the exciplexes form aligned dipoles perpendicular to the Frenkel excitons, as observed in back focal plane photoluminescence images. The angular chromism of exciplexes observed in the 100 meV range indicates possible delocalization and angle-sensing photonic applications. The blue shift of the peak position and increase in the linewidth of photoluminescene spectra with increasing excitation power are caused by the repulsive aligned exciplex dipole moments with a long lifetime (4.65 μs). Electroluminescence spectra of the exciplex from organic light-emitting diodes using the bilayer are blue-shifted with increasing bias, suggesting unidirectional alignment of the exciplex dipole moments. The observation of exciplex dipole moment alignments across molecular interfaces can facilitate the controlled coupling of exciton species and increase efficiency of organic light-emitting diodes.

The directional features of dipole moments of Frenkel excitons and exciplexes are important for optoelectronic applications. Here, the authors study photo- and electro-luminescence emissions of organic heterostructures and observe angular chromism of exciplexes, indicating possible delocalization.

Details

Title
Observation of aligned dipoles and angular chromism of exciplexes in organic molecular heterostructures
Author
Lee, Sang-hun 1   VIAFID ORCID Logo  ; Kim, Taek Joon 1   VIAFID ORCID Logo  ; Lee, Eunji 2 ; Kwon, Dayeong 1 ; Kim, Jeongyong 2   VIAFID ORCID Logo  ; Joo, Jinsoo 1   VIAFID ORCID Logo 

 Korea University, Department of Physics, Seoul, Republic of Korea (GRID:grid.222754.4) (ISNI:0000 0001 0840 2678) 
 Sungkyunkwan University, Department of Energy Science, Suwon, Republic of Korea (GRID:grid.264381.a) (ISNI:0000 0001 2181 989X) 
Pages
7190
Publication year
2023
Publication date
2023
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2887157711
Copyright
© The Author(s) 2023. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.