Advances in Blue Exciplex–Based Organic Light-Emitting Materials and Devices

Abstract

Exciplexes possessing thermally activated delayed fluorescence (TADF) characteristics have received much attention in the fields of organic light-emitting materials and devices over the past decade. In general, an exciplex is a physical mixture between a donor (D) with hole transport properties and an acceptor (A) with electron transport characteristics, and the energy difference between the lowest excited singlet state and the lowest excited triplet state is usually fairly small in terms of the long-range charge-transfer process from D to A. In the processes of photoluminescence and electroluminescence, triplet excitons can be converted to singlet excitons through reverse intersystem crossing and then radiate photons to achieve TADF. As a consequence, triplet excitons can be effectively harvested, and the exciton utilization can be significantly enhanced. Up to now, a large number of exciplexes have been developed and applied to organic light-emitting devices. Notably most of them showed green or red emission, while blue exciplexes are relatively few owing to the spectrum characteristics of the large red-shift and broadened emission. In this study, the latest progress of blue exciplex–based organic light-emitting materials and devices is briefly reviewed, and future research is prospected.

Bidirectional photomagnetism, exciplex fluorescence and dielectric anomalies in a spin crossover Hofmann-type coordination polymer

“…32–43 For example, exciplex fluorescence is red-shifted and often with a long lifetime in comparison with monomer fluorescence, which has received great attention in the fields of exciplex-based organic light-emitting materials and devices. 44–47 The pyrene molecule as a typical intermolecular exciplex was introduced into a three-dimensional (3D) Hofmann-type metal–organic framework (MOF) [Fe(bpben){Au(CN) 2 } 2 ] (bpben = 1,4-bis(4-pyridyl)benzene), which exhibited synergy between exciplex fluorescence and SCO properties. 48…”

Simulating Excited-State Complex Ensembles: Fluorescence and Solvatochromism in Amine-Arene Exciplexes

“…Numerous experimental and theoretical studies have investigated the electronic structure and properties of excimers and exciplexes. [4][5][6][7][8][9][10][11][12] Such studies facilitate applications in organic light-emitting diodes (OLEDs) via thermally activated delayed fluorescence (TADF), [13][14][15][16][17] solar energy harvesting via singlet fission, [18][19][20] chemo-sensors for anion and cationic surfactant sensing [21][22][23][24][25] and bio-detectors, 26,27 and photoredox catalysis. [28][29][30] Advances in quantum chemistry methods have facilitated accurate modeling of excited states in isolated molecules as well as in the condensed phase.…”

Organic molecules with inverted singlet-triplet gaps

“…Over the past decade, TADF molecules have been widely studied in light of the merits of high efficiency as well as low cost, and a number of TADF emitters have been developed ( Jeon et al, 2019 ; Li et al, 2021c ). Up to now, there are several pathways to realize TADF, such as traditional single molecule-based TADF ( Uoyama et al, 2012 ; Zhang et al, 2012 ; Li et al, 2021d ), exciplex-based TADF ( Goushi et al, 2012 ; Li et al, 2014a ; Oh et al, 2015 ; Li et al, 2021a ; Li et al, 2021b ; Xue and Xie, 2021 ; Li et al, 2022c ; Gu et al, 2022 ), aggregation-induced emission (AIE)-based TADF ( Zhao et al, 2018 ; Liu et al, 2020 ), excited-state intramolecular proton transfer (ESIPT)-based TADF ( Mamada et al, 2017 ; Long et al, 2020 ) and multiple resonance-based TADF (MR-TADF) ( Lee et al, 2020 ; Stavrou et al, 2021 ; Wu et al, 2021 ; Yang et al, 2022 ; Zou et al, 2022 ). Particularly, MR-TADF molecules have been considered as the most promising TADF materials on account of the attainment of both high efficiencies and high color purity.…”