Polymorph‐Dependent Thermally Activated Delayed Fluorescence Emitters: Understanding TADF from a Perspective of Aggregation State

Zheng, Kaiyuan; Ni, Fan; Chen, Zhanxiang; Zhong, Cheng; Yang, Chuluo

doi:10.1002/ange.201913210

Cited by 60 publications

(3 citation statements)

References 44 publications

(4 reference statements)

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“…Implementing the techniques found in the works mentioned above to TADF systems becomes somewhat more complicated as there is now not just the behavior of the prompt singlet emission to explain but also the processes and energetics underlying rISC and delayed emission. Functional phenomena in TADF systems as a result of intermolecular interactions have been observed for a range of D-A and D-A-D systems (Hladka et al, 2018;Huang et al, 2018;Klimash et al, 2018;Pashazadeh et al, 2018;Shi et al, 2018;Skuodis et al, 2018;Bhatia and Ray, 2019;Zheng et al, 2019). These works provide methodologies and insights in understanding the influence that intermolecular interactions have on TADF emitters including their photophysical properties.…”

Section: Novel Tadf Emitters Exhibiting Functional Behaviormentioning

confidence: 87%

“…Polymorphism as one of the causes of different TADF behavior in crystalline films/powders is reported by Zheng et al (2019) in 4,4 ′ -(6-(9,9-dimethylacridin-10(9H)-yl)quinoxaline-2,3-diyl)dibenzonitrile (DMAC-CNQ) and 4,4 ′ -(6-(9,9-dimethylacridin-10(9H)-yl)-7-fluoroquinoxaline-2,3-diyl)dibenzonitrile (FDMAC-CNQ). The authors reported two different polymorphs for DMAC-CNQ, which they termed Y-crystal and O-crystal and three polymorphs for FDMAC-CNQ termed Y-crystal, O-crystal and R-crystal based on the emission color (Yellow, Orange and Red).…”

Section: Novel Tadf Emitters Exhibiting Functional Behaviormentioning

confidence: 99%

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Thermally Activated Delayed Fluorescence: Beyond the Single Molecule

Etherington

2020

Front. Chem.

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Emitters that exhibit thermally activated delayed fluorescence (TADF) are of interest for commercial applications in organic light-emitting diodes (OLEDs) due to their ability to achieve internal quantum efficiency of 100%. However, beyond the intrinsic properties of these materials it is important to understand how the molecules interact with each other and when these interactions may occur. Such interactions lead to a significant red shift in the photoluminescence and electroluminescence, making them less practicable for commercial use. Through summarizing the literature, covering solid-state solvation effects and aggregate effects in organic emitters, this mini review outlines a framework for the complete study of TADF emitters formed from the current-state-of-the-art techniques.

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Section: Novel Tadf Emitters Exhibiting Functional Behaviormentioning

confidence: 87%

Section: Novel Tadf Emitters Exhibiting Functional Behaviormentioning

confidence: 99%

Thermally Activated Delayed Fluorescence: Beyond the Single Molecule

Etherington

2020

Front. Chem.

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“…Recently, Li and co-workers have shown regulation of TADF and RTP by modulating J- and H-aggregation through polymorph engineering . The relationship between the aggregated states and TADF was carefully investigated by Zheng et al However, all of these investigations were performed after the system reached the most stable thermodynamically controlled macrocrystalline state. The different metastable kinetically controlled crystalline states have not been vividly explored.…”

Section: Introductionmentioning

confidence: 99%

Polymorphism-Mediated Regulation of Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence via Intra- and Intermolecular Charge Transfer

Pattanayak,

Nandi,

Purkayastha

2023

Chem. Mater.

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Even though there is a vast library of self-assembled organic molecules offering practically infinite possibilities to produce thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), obtaining both from a single candidate is a formidable challenge due to the difficulty in controlling the excited-state dynamics. Here, we demonstrate how a single polymorphic molecule with a donor−acceptor−donor (D−A−D) architecture can be used to regulate both TADF and RTP with the help of polymorph engineering. Thermodynamically controlled macrocrystals show TADF due to intermolecular charge transfer (inter-CT), which reduces the singlet−triplet energy gap (ΔE S−T ), enhances reverse intersystem crossing (RISC), and boosts the delayed singlet radiative decay. The energy gap in kinetically controlled self-assembled microcrystals is greater due to larger intermolecular distance and hence weaker inter-CT. On the other hand, the presence of stronger intramolecular charge transfer (intra-CT), in addition to restricted RISC in the microcrystals, stabilizes the triplet excitons to favor RTP.

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Reversibly Photoswitchable Tristate Fluorescence within a Single Polymeric Nanoparticle

Zhang

Liu

et al. 2021

Advanced Optical Materials

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optical memories, sensors, bioimaging, white-light generation, and anticounterfeiting. [1][2][3][4][5][6][7][8][9][10][11] A variety of stimuli-responsive multistate fluorescent materials in response to a mixing combination of various stimuli such as light, electricity, temperature, pH, ions, solvent vapor, and grinding/smearing have been investigated recently. [12][13][14][15][16][17][18][19][20][21][22][23][24] Among different stimuli, light shows the advantage of remote and noncontact control, dose-dependent, waste-free, noninvasive, high spatial and temporal resolutions, and thus is frequently employed as the external stimulus. [25][26][27][28][29][30] To build a photoswitching mechanism into the systems, photochromic groups like diarylethene (DTE) or spiropyran (SP) derivatives are normally utilized. [31][32][33][34][35][36][37][38][39][40][41][42][43] These systems are mainly made from one photoresponsive and one or two nonphotoresponsive fluorescent groups and thus show ratiometric color change. In such design, the variation of fluorescence color changes is generally limited due to the spectral crosstalk, which hinders their practical applications. [44][45][46] To address this issue, the concept of photoswitchable multistate fluorescent nanosystems has been proposed recently. [47][48][49][50][51][52][53][54][55][56] These systems combine different diarylethene derivatives and can display distinguishable multiple changes in the emission colors. Despite this progress, the systems currently available still do not meet the criteria required for practical application at the same time, including i) distinct multistate emissions with high contrast and the minimum crosstalk between them, ii) emission intensity and color that can be finely tuned, iii) high brightness, excellent water-dispersibility, photoreversibility and storage stability, and iv) versatility in material synthesis and processing for instantaneous application.Herein, we report a class of novel photoswitchable tristate fluorescent polymeric nanoparticles (TS-PFPNs) by covalently incorporating a well-designed photoswitchable fluorescent dyad and two additional photochromic acceptors into a single polymeric nanoparticle. Scheme 1 shows our design. The perylenediimide-spiropyran conjugate (PDI-SP) was selected as the photoswitchable dyad while spiropyran-linked methacrylate (SPMA) and diarylethene derivative (DTEo-1) were employed as the additional acceptors for obtaining ultrahigh-contrast states between three fluorescence states. Without any fluorescenceresonance energy transfer (FRET), the system is expected to show green emission of PDI. When the SP unit of PDI-SP and SPMA would be transferred into its ring-opening merocyanine Herein, a class of novel photoswitchable tristate fluorescent polymeric nanoparticles (TS-PFPNs) consisting of a well-designed perylenediimide-spiropyran conjugate (PDI-SP), two energy-matched photochromics as spiropyran-linked methacrylate and diarylethene (DTE) derivative (DTEo-1) is described. By optimizing the feed ratio ...

show abstract

Polymorph‐Dependent Thermally Activated Delayed Fluorescence Emitters: Understanding TADF from a Perspective of Aggregation State

Cited by 60 publications

References 44 publications

Thermally Activated Delayed Fluorescence: Beyond the Single Molecule

Thermally Activated Delayed Fluorescence: Beyond the Single Molecule

Polymorphism-Mediated Regulation of Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence via Intra- and Intermolecular Charge Transfer

Reversibly Photoswitchable Tristate Fluorescence within a Single Polymeric Nanoparticle

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