Molecular Design Strategy for a Two-Component Gel Based on a Thermally Activated Delayed Fluorescence Emitter

Abstract

Luminescent materials that can spontaneously assemble into highly ordered networks are essential to improve the quality of thin films in stacked device architectures and enhance the performances of solution processed OLEDs. Herein, we report two pyridine-decorated thermally activated delayed fluorescence (TADF) emitters, 3PyCzBP and 4PyCzBP. 4PyCzBP shows robust two component gel formation in the presence of either tartaric acid or succinic acid along with significant emission enhancement. Morphology studies reveal that these gels consist of homogeneous nanofibers assembled in hierarchical supramolecular networks. Transient photoluminescence spectra confirm that the gels emit via a TADF mechanism, making them the first examples of TADF gels. These nanofibers are promising candidates as self-assembled emitting nanofibers in thin films in solution-processed OLEDs.

Photoinduced Energy and Electron Transfer Between a Photoactive Cage Based on a Thermally Activate Delayed Fluorescence Ligand and Encapsulated Fluorescent Dyes

“…(4-(3,6-di(pyridin-3,4-yl)-9H-carbazol-9-yl)phenyl)(phenyl)methanone), the former of which was used to make two component supramolecular gels. 43 The TADF nature of 4PyCzBP and 3PyCzBP was confirmed through a combination of steady-state and timeresolved emission spectroscopy measurements. [43][44] When 4PyCzBP and [Pd(NCMe) 4 ](BF 4 ) 2 were heated in a 2:1 ratio in DMSO- (Table S3).…”

“…43 The TADF nature of 4PyCzBP and 3PyCzBP was confirmed through a combination of steady-state and timeresolved emission spectroscopy measurements. [43][44] When 4PyCzBP and [Pd(NCMe) 4 ](BF 4 ) 2 were heated in a 2:1 ratio in DMSO- (Table S3). Therefore, 4PyCzBP-Pd does not emit via a TADF mechanism but only from singlet excited states.…”

“…TEM images of the nanostructures of 4PyCzBP-Pd.The emission profile of 4PyCzBP-Pd in DCM(Figure 4a) is broader and red-shifted at 555 nm with a lower photoluminescence quantum yield, F PL , of 4% compared to that of 4PyCzBP (l max = 477 nm, F PL = 52%) 43. Similarly, the emission of 4PyCzBP-Pd in PMMA-doped film is red-shifted at 553 nm with a F PL of 5% compared to the emission observed for 4PyCzBP(l max = 447 nm, F PL = 21%).…”

Fast Delayed Emission in New Pyridazine-Based Compounds

“…Among the N -heterocyclic electron-acceptors, 1,3,5-triazine is one of the most employed (Wong and Zysman-Colman, 2017 ; Huang et al, 2019 ; Sharma et al, 2019 ; Wang et al, 2019 ; Woo et al, 2019 ). Other heterocycles used in this role include pyridines (Rajamalli et al, 2017 , 2018a , b , 2019 ), pyrimidines (Komatsu et al, 2016 ; Nakao et al, 2017 ; dos Santos et al, 2019 ), and pyrazines ( Figure 1A ) (dos Santos et al, 2019 ; Kato et al, 2019 ; Liu et al, 2019 ). Missing from this family of heterocycles is pyridazine (Pydz), which is investigated in this work as an acceptor in three novel D-A compounds ( Figure 1B ).…”

Luminescent Behavior of Gels and Sols Comprised of Molecular Gelators

“…E-type delayed fluorescence was first found with eosin [ 45 ]. Both prompt and TADF were documented in dichloromethane solutions of a pyridinyl-carbazole-based molecules, 4PyCzBP ( Figure 4 ) [ 46 ]. When one equivalent of L-tartaric acid was added, a gel formed due to H-bonding interactions between a carboxylic acid group and a nitrogen atom of a pyridinyl group; the CGC value was 3 mg/mL.…”