Delayed Fluorescence by Triplet–Triplet Annihilation from Columnar Liquid Crystal Films

Delayed Fluorescence by Triplet–Triplet Annihilation from Columnar Liquid Crystal Films

Delayed fluorescence (DF) by triplet–triplet annihilation (TTA) is observed in solutions of a benzoperylene-imidoester mesogen that shows a hexagonal columnar mesophase at room temperature in the neat state. A similar benzoperylene-imide with a slightly smaller HOMO–LUMO gap, that also is hexagonal...

Full description

Saved in:
Bibliographic Details
Published in:ACS applied electronic materials Vol. 4; no. 7; pp. 3486 - 3494
Main Authors: Franca, Larissa G., dos Santos, Paloma L., Pander, Piotr, Cabral, Marília G. B., Cristiano, Rodrigo, Cazati, Thiago, Monkman, Andrew P., Bock, Harald, Eccher, Juliana
Format: Journal Article
Language:English
Published: United States American Chemical Society 26-07-2022
Subjects:
Chemical Sciences
triplet−triplet annihilation
optical spectroscopy
columnar liquid crystals
delayed fluorescence
solution-processed OLED
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Delayed fluorescence (DF) by triplet–triplet annihilation (TTA) is observed in solutions of a benzoperylene-imidoester mesogen that shows a hexagonal columnar mesophase at room temperature in the neat state. A similar benzoperylene-imide with a slightly smaller HOMO–LUMO gap, that also is hexagonal columnar liquid crystalline at room temperature, does not show DF in solution, and mixtures of the two mesogens show no DF in solution either, because of collisional quenching of the excited triplet states on the imidoester by the imide. In contrast, DF by TTA from the imide but not from the imidoester is observed in condensed films of such mixtures, even though neat films of either single material are not displaying DF. In contrast to the DF from the monomeric imidoester in solution, DF of the imide occurs from dimeric aggregates in the blend films, assisted by the imidoester. Thus, the close contact of intimately stacked molecules of the two different species in the columnar mesophase leads to a unique mesophase-assisted aggregate DF. This constitutes the first observation of DF by TTA from the columnar liquid crystalline state. If the imide is dispersed in films of polybromostyrene, which provides an external heavy-atom effect facilitating triplet formation, DF is also observed. Organic light-emitting diodes (OLEDs) devices incorporating these liquid crystal molecules demonstrated high external quantum efficiency (EQE). On the basis of the literature and to the best of our knowledge, the EQE reported is the highest among nondoped solution-processed OLED devices using a columnar liquid crystal molecule as the emitting layer.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:2637-6113
2637-6113
DOI:10.1021/acsaelm.2c00432