Excimer-emitting single molecules with stacked π-conjugated groups covalently linked at the 1,8-positions of naphthalene for highly efficient blue and green OLEDs

Hu, Jian‐Yong; Pu, Yong‐Jin; Yamashita, Yusuke; Satoh, Fumiya; Kawata, So; Katagiri, Hiroshi; Sasabe, Hiroyuki; Kido, Junji

doi:10.1039/c3tc30319e

Cited by 61 publications

(32 citation statements)

References 41 publications

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“…Meanwhile, the peripheral carbazole moiety will also act as an intermolecular contact platform, adding further stabilization via the weak π-stacking interactions. 22 These types of arrangement may be beneficial for the excimer formation in the solid state. 23 As a comparison, the addition of a tert -butyl group on the anthracene moiety of Cz 9 PhAn forms Cz 9 PhAnt (see Scheme 1 ).…”

Section: Resultsmentioning

confidence: 99%

Insight into the mechanism and outcoupling enhancement of excimer-associated white light generation

et al. 2016

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Section: Resultsmentioning

confidence: 99%

Insight into the mechanism and outcoupling enhancement of excimer-associated white light generation

et al. 2016

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“…But due to the great steric hindrance at C1 site of fluorene, [ 11 ] the last‐step Pd‐catalyzed coupling gave no product. The synthetic failure is an important hint: in previous reports, [ 12 ] the researchers had not met similar difficulty when they introduced D/A units in short spatial distance via coupling reaction, indicating other molecular backbones to hold close D/A units were still somewhat flexible. But in our cases, the bulky and robust spiro‐backbone prevented coupling reaction from happening at the adjacent C1 site.…”

Section: Figurementioning

confidence: 99%

Highly Efficient Thermally Activated Delayed Fluorescence via an Unconjugated Donor–Acceptor System Realizing EQE of Over 30%

et al. 2020

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basically limited to donor (D)-π-acceptor (A) molecular architecture. [2] This type of molecular design, first proposed by Adachi and co-workers for TADF, [1a] can tune their D or/and A groups, geometries, and steric hindrance between them to generate twisted induced charge-transfer-type emission. [3] The twisted dihedral angle between D and A units can minimize the singlettriplet splitting energy (ΔE ST) for fast RISC, [1c,4] but the resulted TADF OLEDs still need to be significantly improved, notably in terms of efficiency roll-off at high brightness and concentration quenching because of the ππ intermolecular interactions in the solid-state. [5] Another way to achieve TADF is to use D/A complex, in which the D/A blocks are spatially isolated, but their forming exciplexes are far less efficient than D-π-A analogs, and the resulting OLEDs also display severe efficiency roll-off. [6] Recently, researchers conceptually consider that the intramolecular noncovalent interaction between D/A units in faceto-face alignment could be a new option to realize TADF. [7] Constructing TADF materials in this unconjugated way has the potential to combine the small ΔE ST value with substantial transition dipole and achieve high luminescent efficiency. [8] These two electron-rich and electron-poor π-systems need to be held close in space to form homoconjugation. In this regard, The ORCID identification number(s) for the author(s) of this article can be found under

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“…In this context, naphthalene‐1,8‐diyl linker units have attracted considerable attention for the synthesis of sterically crowded structures,18 electron transfer through proximal π‐systems,19 and organic light‐emitting diode (OLED) materials based on emission from the excimer state 3a. 20 Most of these studies have focused on dimer structures having a covalent linker at only one side or at the center of the chromophore 9b. In contrast, only a few examples have been reported of cyclic dimer structures linked on either side by two naphthalene‐1,8‐diyl units 21…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Enhancement of Covalently Linked 1‐Cyano‐1,2‐diphenylethene Chromophores with Naphthalene‐1,8‐diyl Linker Units: Analysis Based on Kinetic Constants

Hirose

Tsunoi

Fujimori

et al. 2014

Chemistry A European J

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The fluorescence enhancement effect of covalently fixed fluorescent chromophores has been investigated by means of kinetic analysis of decay rate constants and theoretical calculations. Derivatives of 1-cyano-1,2-diphenylethene dimer have a distorted cyclic structure when both ends are clipped with two naphthalene-1,8-diyl linker units. In contrast to the reference monomer derivative, which exhibits only slight fluorescence in solution (Φf < 0.01, τf < 0.1 ns), the dimer derivative shows high fluorescence quantum yield (Φf = 0.55) and long lifetime (τf = 20.6 ns) in dilute solution owing to suppression of the nonradiative decay process (knr = 0.022 ns(-1)). A V-shaped derivative with a covalent linker on one side showed moderate quantum yield and lifetime (Φf = 0.12, τf = 4.9 ns). According to the wavelength shifts of the absorption/fluorescence bands and theoretical calculations by time-dependent density functional theory (TD-DFT), we propose an H-aggregate-type excimer interaction.

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Excimer-emitting single molecules with stacked π-conjugated groups covalently linked at the 1,8-positions of naphthalene for highly efficient blue and green OLEDs

Cited by 61 publications

References 41 publications

Insight into the mechanism and outcoupling enhancement of excimer-associated white light generation

Insight into the mechanism and outcoupling enhancement of excimer-associated white light generation

Highly Efficient Thermally Activated Delayed Fluorescence via an Unconjugated Donor–Acceptor System Realizing EQE of Over 30%

Fluorescence Enhancement of Covalently Linked 1‐Cyano‐1,2‐diphenylethene Chromophores with Naphthalene‐1,8‐diyl Linker Units: Analysis Based on Kinetic Constants

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