Tetrasubstituted-pyrene derivatives for electroluminescent application

Muangpaisal, Rossatorn; Ho, Ming-Chi; Huang, Teng‐Yi; Chen, Chih-Hsin; Shen, Jau-Ji; Ni, Jen‐Shyang; Lin, Jiann T.; Ke, Tung Huei; Chen, Li Yin; Wu, Chung‐Chih; Tsai, Chia‐Cheng

doi:10.1016/j.orgel.2014.06.003

Cited by 9 publications

(3 citation statements)

References 35 publications

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“…Moreover, the maxima absorption peaks at around 369–379 nm become dominant in the absorption spectra of P2F and P3F , which is in accord with the fact that the content of the oligofluorene-diphenylamine arms increases significantly with an extension of the oligofluorene arm length. These assignments match well with previous studies on 1,3,6,8-tetraphenylpyrene derivatives − and diphenylamine dendrimers. − The absorption characteristics of P1F – P3F in films are similar to those recorded from dilute solutions except slight red shifts (7–12 nm).…”

Section: Results and Discussionsupporting

confidence: 90%

“…The maxima absorption peaks at around 369–379 nm mainly originate from the π–π* transition of the oligofluorene-diphenylamine arms, which are progressively red-shifted with an extension of the arm length from P1F to P3F . The absorption peak at around 407 nm for P1F may be assigned to the π–π* absorption due to the donor–acceptor electronic coupling that causes electron transfer between the diphenylamine and the pyrene core via the oligofluorene bridge. − Such electronic coupling effects strongly depend on the distance between the donor and the acceptor, and become negligible with increasing the oligofluorene arm length for P2F and P3F . Moreover, the maxima absorption peaks at around 369–379 nm become dominant in the absorption spectra of P2F and P3F , which is in accord with the fact that the content of the oligofluorene-diphenylamine arms increases significantly with an extension of the oligofluorene arm length.…”

Section: Results and Discussionmentioning

confidence: 99%

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Pyrene-Cored Starburst Oligofluorenes with Diphenylamine End-Cappers: Design, Synthesis, Stabilized Optical Gain, and Lasing Properties

Zhang

Lai

et al. 2017

J. Phys. Chem. C

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A family of starburst conjugated molecules composed of a pyrene core and diphenylamine end-cappers with various oligofluorene bridge lengths, named as P1F, P2F, and P3F, were designed, synthesized, and characterized. The resulting materials exhibited good photoluminescence (PL) properties and excellent thermal stability with high degradation temperatures (T d, the temperature with 5% weight loss) over 400 °C. A combination of the thermal, photophysical, electrochemical, fluorescence transients, electroluminescence (EL), amplified spontaneous emission (ASE), and lasing measurements were carried out to reveal further the influence of the diphenylamine moieties as electron-donating end-cappers on their optoelectronic properties. It is interesting to find that the PL spectra are significantly blue-shifted for P2F (∼11–15 nm) and P3F (∼14–22 nm) relative to those of P1F in both dilute solutions and films with an extension in the conjugation length of the oligofluorenes, which is quite different from the common phenomenon of red-shifted PL spectra for the general starburst molecules with increasing the conjugation length. It is supposed that the introduction of strong electron-donating diphenylamine units helps to construct donor-π-acceptor structures that enable intramolecular excitation energy transfer transition from the diphenylamine donor to the pyrene acceptor. The diphenylamine units also play a key role in raising the highest occupied molecular orbital (HOMO) energy levels of the molecules, which is beneficial for improving the charge injection and transport properties. Consequently, efficient EL properties with rather low turn-on voltages of 2.7–3.0 V among nondoped blue OLEDs have been achieved. Moreover, stabilized EL and ASE with high net gain coefficients (around 73.6–81.9 cm–1) and low waveguide loss (about 2.10–4.90 cm–1) have been demonstrated. One dimensional distributed feedback (1D DFB) lasers demonstrated a low lasing threshold of 2.1 kW cm–2 (25 nJ pulse–1) at 475 nm for P2F. All the results confirm that the novel molecular design strategy on constructing diphenylamine-capped pyrene-centered starburst molecules can obviously improve the EL performance by fine modulating the HOMO energy levels, but did not largely sacrifice their optical gain properties. The high gain and low loss with excellent thermal and optical stability have rendered these donor-π-acceptor starburst conjugated molecules rather attractive as robust gain media for organic lasers.

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Section: Results and Discussionsupporting

confidence: 90%

Section: Results and Discussionmentioning

confidence: 99%

Pyrene-Cored Starburst Oligofluorenes with Diphenylamine End-Cappers: Design, Synthesis, Stabilized Optical Gain, and Lasing Properties

Zhang

Lai

et al. 2017

J. Phys. Chem. C

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“…Pyrene is ap olycyclic aromatic hydrocarbon with high prospects for use in the fields of physicalc hemistrya nd material sciences, and its photophysical propertiesh aveb een well-characterized. [1] To modulate the photophysical properties of pyrene, various pyrene derivatives have been developed by incorporating (hetero)aryl, [2] alkenyl, [3] alkynyl, [4] and heteroatom groups [5] into the pyrenec ore. Regulating the photophysical properties such as fluorescencew avelength,q uantum yields, and lifetimes of pyrenes in solution can be achieved by introducing the aforementioned substituents.…”

Section: Introductionmentioning

confidence: 99%

Molecular Packing and Solid‐State Photophysical Properties of 1,3,6,8‐Tetraalkylpyrenes

Iwasaki

Murakami

Takeda

et al. 2019

Chemistry A European J

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The relationship between the photophysical properties and molecular orientation of 1,3,6,8‐tetraalkylpyrenes in the solid state is described herein. The introduction of alkyl groups with different chain structures (in terms of length and branching) did not affect the photophysical properties in solution, but significantly shifted the emission wavelengths and fluorescence quantum yields in the solid state for some samples. Pyrenes bearing ethyl, isobutyl, or neopentyl groups at the 1‐, 3‐, 6‐, and 8‐positions showed similar emission profiles in both the solution and solid states. In contrast, pyrenes bearing other alkyl groups exhibited an excimer emission in the solid state, similar to that of the parent pyrene. On studying the photophysical properties in the solid state with respect to the obtained crystal structures, the observed solid‐state photophysical properties were found to depend on the relative position of the pyrene chromophores. The solid‐state photophysical properties can be controlled by the alkyl groups, which provide changing crystal packing. Among the pyrenes tested, 1,3,6,8‐tetraethylpyrene showed the highest fluorescence quantum yield of 0.88 in the solid state.

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Monodisperse Six‐Armed Starbursts based on Truxene‐Cored Multibranched Oligofluorenes: Design, Synthesis, and Stabilized Lasing Characteristics

Zhang

Liu

et al. 2019

Chemistry A European J

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A series of monodisperse six‐armed conjugated starbursts (Tr1F, Tr2F, and Tr3F) containing a truxene core and multibranched oligofluorene bridges capped with diphenylamine (DPA) units has been designed, synthesized, and investigated as robust gain media for organic semiconductor lasers (OSLs). The influence of electron‐rich DPA end groups on their optoelectronic characteristics has been discussed at length. DPA cappers effectively raise HOMO levels of the starbursts, thus enhancing the hole injection and transport ability. Solution‐processed electroluminescence devices based on the resulting six‐armed starbursts exhibited efficient deep‐blue electroluminescence with clear reduced turn‐on voltages (3.2–3.5 V). Moreover, the resulting six‐armed molecules showed stabilized electroluminescence and amplified spontaneous emission with low thresholds (27.4–63.9 nJ pulse−1), high net gain coefficients (80.1–101.3 cm−1), and small optical loss (2.6–4.4 cm−1). Distributed feedback OSLs made from Tr3F exhibited a low lasing threshold of 0.31 kW cm−2 (at 465 nm). The results suggest that the construction of truxene‐centered six‐armed conjugated starbursts with the incorporation of DPA units can effectively enhance EL properties by precisely regulating the HOMO energy levels, and further optimizing their optical gain properties.

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Tetrasubstituted-pyrene derivatives for electroluminescent application

Cited by 9 publications

References 35 publications

Pyrene-Cored Starburst Oligofluorenes with Diphenylamine End-Cappers: Design, Synthesis, Stabilized Optical Gain, and Lasing Properties

Pyrene-Cored Starburst Oligofluorenes with Diphenylamine End-Cappers: Design, Synthesis, Stabilized Optical Gain, and Lasing Properties

Molecular Packing and Solid‐State Photophysical Properties of 1,3,6,8‐Tetraalkylpyrenes

Monodisperse Six‐Armed Starbursts based on Truxene‐Cored Multibranched Oligofluorenes: Design, Synthesis, and Stabilized Lasing Characteristics

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