Efficient non-doped bluish-green organic light emitting devices based on N1 functionalized star-shaped phenanthroimidazole fluorophores

Tagare, Jairam; Ulla, Hidayath; Satyanarayan, M. N.; Vaidyanathan, Sivakumar

doi:10.1016/j.jphotochem.2017.11.001

Cited by 27 publications

(16 citation statements)

References 64 publications

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“…PITPA-3 showed a small red shift of 23 nm, due to its large molecular twisting nature ( Figure S25) Stokes' shift (Δ ν) as a function of Δf: [44,45] Δ…”

Section: Powder Xrd Studiesmentioning

confidence: 99%

Phenanthroimidazole‐based chromophores for organic light‐emitting diodes: synthesis, photophysical, and theoretical study

et al. 2020

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Organic light‐emitting diodes (OLED) are gaining attention and making a significant contribution to the area of lighting and displays technology. The synthesis of new materials that can act as a host as well as emissive materials is crucial and efforts have been made in this direction in this research. Here, four star‐shaped fluorophores, with a donor–acceptor (D–A) structure and with triphenylamine and phenanthroimidazole groups with different substitutions at the N1 position of the imidazole moiety, were designed and synthesized. Synthesized fluorophores showed sufficient thermal stability (10% Td in the range 230–280°C). Ultraviolet–visible (UV–vis) spectra of the fluorophores showed multiple absorption bands (bands in the UV region, due to π–π* transitions of the conjugated aromatic portion) and all fluorophores showed blue emission in dichloromethane solution. Electrochemical analysis indicated that all fluorophores had excellent oxidation and reduction characteristics. Theoretical calculations were also performed to better understand the structural and electronic properties of the synthesized fluorophores. All fluorophores had higher triplet (T1) energy (ranging from 2.49–2.52 eV) than the widely used green (Ir(ppy)3 –2.4 eV) and red (Ir (piq)2 acac – 2.2 eV) dopant materials. These results indicated that these fluorophores would be useful as host materials for efficient green and red phosphorescent OLEDs.

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“…PITPA-3 showed a small red shift of 23 nm, due to its large molecular twisting nature ( Figure S25) Stokes' shift (Δ ν) as a function of Δf: [44,45] Δ…”

Section: Powder Xrd Studiesmentioning

confidence: 99%

Phenanthroimidazole‐based chromophores for organic light‐emitting diodes: synthesis, photophysical, and theoretical study

et al. 2020

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“…Furthermore, the frontier molecular orbital of TPA moieties has the highest occupied molecular orbital (HOMO), which enables efficient hole injection compared to other moieties and a work function near that of indium tin oxide (ITO) or N,N -Di(1-naphthyl)-N,N -diphenyl-(1,1 -biphenyl)-4,4 -diamine (NPB), which are generally used as holetransporting materials [30]. Currently, however, phenanthroimidazole/diphenylimidazole-based moieties are widely used to make deep-blue fluorophores due to their wide absorption and bright luminescent property [31][32][33]. Combinations of imidazole-based derivatives with TPA assist as effective donor-π -acceptor (D-π -A) bipolar materials [34].…”

Section: Introductionmentioning

confidence: 99%

Solution-processed deep-blue (y∼0.06) fluorophores based on triphenylamine-imidazole (donor-acceptor) for OLEDs: computational and experimental exploration

Girase

Nayak

Tagare

et al. 2021

Journal of Information Display

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Developing solution-processable deep-blue emitters for organic light-emitting diodes (OLEDs) is still a challenging task. In this context, two new solution-processable deep-blue emitters, N,were successfully designed and synthesized by incorporating phenanthroimidazole (PI)/diphenylimidazole (BI)-triphenylamine (TPA), which is functional at the N1 position of the imidazole, with Ph-mCF 3 . The thermal, photophysical, and electrochemical properties of both fluorophores were systematically explored. These fluorophores showed a deep-blue emission in the solution as well as in the solid state. The highest occupied molecular orbital (HOMO)lowest unoccupied molecular orbital (LUMO) energy level of the fluorophores was calculated using electrochemical studies and compared with the theoretical calculation [the density functional theory (DFT)]. The asymmetrically twisted conformation of 4-PIMCFTPA between PI-TPA efficiently showed a high photoluminescence quantum yield. OLED (undoped and doped) devices were fabricated with the newly synthesized emitters, and 4-PIMCFTPA demonstrated better electroluminescence (EL) performance than the BI-based emitter. Thus, the OLED based on 4-PIMCFTPA (1 wt% in the CBP host) had the best EL performance, with a maximum external quantum efficiency 1.7% and CIE coordinates of (0.17, 0.06).

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“…Hence, understanding the structure-property fundamentals of substitution effect becomes essential in designing efficient organic light-emitting devices. [28][29][30] On the other hand, carbazole-based materials possessing good hole-transporting nature, favorable triplet energies and multi-functionalized ability have been extensively explored in development of high efficient OLED devices. 31 Although the symmetrical bipolar properties of multi-functionalized carbazole are well known in literature 32 but, the unsymmetrical derivatives featuring donor and acceptor units remain elusive.…”

Section: Introductionmentioning

confidence: 99%

Phenanthroimidazole-based bipolar carbazoles featuring cyano substituents to realize efficient deep-blue electroluminescence with an external quantum efficiency of nearly 6%

et al. 2021

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Efficient non-doped bluish-green organic light emitting devices based on N1 functionalized star-shaped phenanthroimidazole fluorophores

Cited by 27 publications

References 64 publications

Phenanthroimidazole‐based chromophores for organic light‐emitting diodes: synthesis, photophysical, and theoretical study

Phenanthroimidazole‐based chromophores for organic light‐emitting diodes: synthesis, photophysical, and theoretical study

Solution-processed deep-blue (y∼0.06) fluorophores based on triphenylamine-imidazole (donor-acceptor) for OLEDs: computational and experimental exploration

Phenanthroimidazole-based bipolar carbazoles featuring cyano substituents to realize efficient deep-blue electroluminescence with an external quantum efficiency of nearly 6%

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