Design strategies for materials showing thermally activated delayed fluorescence and beyond: Towards the fourth‐generation OLED mechanism

Yersin, Hartmut; Mătărângă-Popa, Larisa N.; Li, Shuwei; Czerwieniec, Rafał

doi:10.1002/jsid.654

Cited by 31 publications

(20 citation statements)

References 31 publications

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“…This material concept will lead us to beyond TADF and might successfully be applied for next generation OLEDs. 41,42 Novel molecular systems of this type and novel biaryl TADF dyes are currently under investigation.…”

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confidence: 99%

Design of Conformationally Distorted Donor–Acceptor Dyads Showing Efficient Thermally Activated Delayed Fluorescence

Sommer

Mătărângă-Popa

Czerwieniec

et al. 2018

J. Phys. Chem. Lett.

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A highly potent donor-acceptor biaryl thermally activated delayed fluorescence (TADF) dye is accessible by a concise two-step sequence employing two-fold Ullmann arylation and a sequentially Pd-catalyzed Masuda borylation-Suzuki arylation (MBSA). Photophysical investigations show efficient TADF at ambient temperature due to the sterical hindrance between the donor and acceptor moieties. The photoluminescence quantum yield amounts to Φ = 80% in toluene and 90% in PMMA arising from prompt and delayed fluorescence with decay times of 21 ns and 30 μs, respectively. From an Arrhenius plot, the energy gap Δ E(S - T) between the lowest excited singlet S and triplet T state was determined to be 980 cm (120 meV). A new procedure is proposed that allows us to estimate the intersystem crossing time to ∼10 ns.

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confidence: 99%

Design of Conformationally Distorted Donor–Acceptor Dyads Showing Efficient Thermally Activated Delayed Fluorescence

Sommer

Mătărângă-Popa

Czerwieniec

et al. 2018

J. Phys. Chem. Lett.

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“…Also, donor-acceptor-donor (D-A-D) architectures have been shown to be more efficient compared to D-A systems despite having similar singlet-triplet gaps 8,9,58 . Recently, several new approaches to the design of TADF emitters 16,59,60 and increasing the efficiency of the devices 20,61,62 have been proposed.…”

Section: Two-state Model Of Tadfmentioning

confidence: 99%

Extracting Design Principles for Efficient Thermally Activated Delayed Fluorescence (TADF) from a Simple Four-State Model

Silva

Kim²,

Zhu³

et al. 2019

Preprint

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<p>We introduce a simple quantum-mechanical model for thermally activated delayed fluorescence (TADF). The Hamiltonian is represented in the basis of four spin-mixed diabatic states representing pure charge transfer (CT) and local excitations (LE). The model predicts that it is possible to realize lowest-lying adiabatic singlet (S1) and triplet (T1) states with a small singlet triplet gap, differing CT/LE contributions, and appreciable LE component in the S1 state. These characteristics can explain the coexistence of fast T1→S1 reverse intersystem crossing and S1→S0 radiative decay in some chromophores. Through the sampling of the parameter space and statistical analysis of the data, we show which parameter combinations contribute the most to the TADF efficiency. We also show that conformational fluctuations of a single model donor-acceptor system sample a significant region of the parameter space and can enhance the TADF rate by almost three orders of magnitude. This study provides new guidelines for optimization of TADF emitters by means of electronic structure and conformation engineering. <br></p>

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“…[1,6,[14][15][16] Among them, metal atoms are always involved in the emission processes of organic chromophores, deriving new radiative pathways and opening new important application directions. [1,17] Thermally activated delayed fluorescence (TADF) [2,[17][18][19][20][21][22][23][24][25][26][27][28][29] in a purely organic molecule was first reported in the case of eosin and was also referred to as "E-type" delayed fluorescence. [30] TADF is based on a thermally activated reverse (upconversion) emitters are extensively summarized in Sections 3-5 (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Crystalline Metal‐Organic Materials with Thermally Activated Delayed Fluorescence

Han

Dong

Zang

2021

Advanced Optical Materials

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intersystem crossing (RISC) from the lowest triplet (T 1 ) excited state to the lowest singlet (S 1 ) excited state. The singlet excitons generated in this way from triplet excitons can then decay radiatively to the electronic ground state (S 0 ). [18,19] To utilize both singlet and triplet excitons for enlarging electroluminescence efficiency in organic light-emitting diodes (OLEDs), TADF materials were applied as an emissive layer. In 2009, the first TADF-OLED device was realized based on a Sn(IV)porphyrin complex by Adachi and coworkers [31] In 2011, the real breakthrough of TADF-OLEDs was achieved by using organic molecules. [32] Thereafter, Adachi and co-workers developed a series of purely organic TADF emitters, [33] and achieved internal quantum efficiencies approaching 100%, which hence woke the extensive research interests on TADF materials. [17,20,34] Moreover, the TADF-active organo-copper cluster was also reported for OLED applications with an external quantum efficiency (EQE) of 11% by Matthias. [35] These works demonstrate that both singlet and triplet excitons can be harvested in TADF-OLEDs achieving high performance compared to the fluorescence-emitter-based OLEDs.Great progress has been made on TADF-based metal-organic emitters. [18,19,21,24,25,29,[36][37][38] The transitions metals atoms could support metal-to-ligand charge transfer (MLCT) due to the participation of d electrons in TADF emitters; [21] the metal atoms in the main group could provide favorable coordination modes and/or rigidity for the organic moieties in TADF emitters. [29] Some metal-organic TADF emitters have demonstrated excellent performance in OLED devices and continuously new metal-containing TADF emitters are reported. Currently, small-molecule metal-organic complexes are involved in metals atoms including transitions metal Cu(I), Ag(I), Au(I)/(III), Zn(II), Zr(IV), W(VI), and main group metals Alkali (Li + , Na + , K + , Rb + , Cs + ); ligand-protected metal clusters included Cu(I) clusters, Ag(I) clusters, and Au(0, I) clusters; TADF-based metal-organic coordination polymers have Zr(IV), Zn(II), Ag(I), Cu(I). Although there are some review articles concerning small-molecule metal complexes that exhibiting TADF emission, [18,19,21,24,25,29,[36][37][38] they mainly focus on a or several certain types of metal atoms, [27] or pay attention to the performance of lighting devices. [21] In this review, we aimed to give a full view of emitters containing metal atoms and displaying TADF in the crystalline state or solid-state, which are expected to encourage readers to design more excellent such materials for multifunctions besides electroluminescence.In this review, the detailed requirements for TADF will be discussed in Section 2. Three categories of metal-organic TADF Thermally activated delayed fluorescence (TADF) properties of crystalline metal-organic materials, mainly including small-molecule metal-organic complexes, organic ligand-protected metal clusters, and metal-organic coordination polymers are summarized here. The c...

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Design strategies for materials showing thermally activated delayed fluorescence and beyond: Towards the fourth‐generation OLED mechanism

Cited by 31 publications

References 31 publications

Design of Conformationally Distorted Donor–Acceptor Dyads Showing Efficient Thermally Activated Delayed Fluorescence

Design of Conformationally Distorted Donor–Acceptor Dyads Showing Efficient Thermally Activated Delayed Fluorescence

Extracting Design Principles for Efficient Thermally Activated Delayed Fluorescence (TADF) from a Simple Four-State Model

Crystalline Metal‐Organic Materials with Thermally Activated Delayed Fluorescence

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