Electrical and electro-optical parameters of 4ʹ-octyl-4-cyanobiphenyl nematic liquid crystal dispersed with gold and silver nanoparticles

Mishra, Mukesh; Dąbrowski, R.; Vij, J. K.; Mishra, Ankit; Dhar, Ravindra

doi:10.1080/02678292.2015.1071438

Cited by 22 publications

(9 citation statements)

References 43 publications

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“…The absorption spectrum in toluene of DiKTa-LC (Figure 3a) mirrors those of DiKTa and Mes 3 DiKTa with a lowenergy band at 464 nm at a molar extinction coefficient (ɛ) of around 20 × 10 3 M À 1 cm À 1 associated with the SRCT state, [20] and a high-intensity absorption (ɛ > 100 × 10 3 M À 1 cm À 1 ) band at 305 nm attributed to a superposition of locally excited π-π* transitions from the 4-cyanobiphenyl moieties and the DiKTa core. [23] The photoluminescence (PL) spectrum of DiKTa-LC in toluene shows a narrow emission band (FWHM = 33 nm) with an emission maximum, λ PL , of 487 nm, and a small Stokes shift of 24 nm. The Φ PL of DiKTa-LC is 39 % in oxygen-free toluene, which is comparable to the 37 % measured for Mes 3 DiKTa.…”

Section: Resultsmentioning

confidence: 99%

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

et al. 2023

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The use of thermally activated delayed fluorescence (TADF) emitters and emitters that show preferential horizontal orientation of their transition dipole moment (TDM) are two emerging strategies to enhance the efficiency of OLEDs. We present the first example of a liquid crystalline multi-resonance TADF (MR-TADF) emitter, DiKTa-LC. The compound possesses a nematic liquid crystalline phase between 80 °C and 110 °C. Importantly, the TDM of the spin-coated film shows preferential horizontal orientation, with an anisotropy factor, a, of 0.28, which is preserved in doped poly(vinylcarbazole) films. Green-emitting (λ EL = 492 nm) solution-processed OLEDs based on DiKTa-LC showed an EQE max of 13.6 %. We thus demonstrate for the first time how self-assembly of a liquid crystalline TADF emitter can lead to the so-far elusive control of the orientation of the transition dipole in solutionprocessed films, which will be of relevance for highperformance solution-processed OLEDs.

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Section: Resultsmentioning

confidence: 99%

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

et al. 2023

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“…The absorption spectrum in toluene of DiKTaLC (Figure 4a) mirrors those of DiKTa and Mes3DiKTa with a low-energy band at 464 nm at a molar extinction coefficient (ε) of around 20 ×10 3 M -1 cm -1 associated with the SRCT state, 48 and a high-intensity absorption (ε > 100 ×10 3 M -1 cm -1 ) band at 305 nm attributed to a superposition of locally excited (LE) π-π* transitions from the 4-cyanobiphenyl moieties and the DiKTa core. 54 The photoluminescence (PL) spectrum of DiKTaLC in toluene shows a narrow emission band (FWHM = 33 nm) with an emission maximum, λPL, of 487 nm, and a small Stokes shift of 24 nm.…”

Section: Photophysical Propertiesmentioning

confidence: 99%

Controlling the Emitter Orientation in Solution-processed Films through Introduction of Mesogenic Groups within a Multi-resonance Thermally Activated Delayed Fluorescence Emitter

Chen

Tenopala‐Carmona

Knöller

et al. 2022

Preprint

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The use of thermally activated delayed fluorescence emitters and emitters that show preferential horizontal orientation of their transition dipole are two emerging strategies to enhance the efficiency of organic light-emitting diodes. We present the first example of a liquid crystalline multi-resonance thermally activated delayed fluorescent emitter, DiKTaLC. The neat film of DiKTaLC shows a photoluminescence quantum yield of 41%, a singlet-triplet energy gap, ΔEST, of 0.20 eV, and a delayed lifetime, τd, of 70.2 µs. The compound possesses a nematic discotic liquid crystalline phase between 80 °C and 110 °C. More importantly, the transition dipole moment of the spin-coated film shows preferential horizontal orientation, with an anisotropy factor, a, of 0.26. We thus demonstrate for the first time how self-assembly of a liquid crystalline TADF emitter can lead to the so-far elusive control of the orientation of the transition dipole in solution-processed films, which will be of relevance for high-performance solution-processed organic light-emitting diodes.

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“…[11,12] Doping of nano-objects in FLC matrix has their effect on switching time, spontaneous polarisation and rotational viscosity and photoluminescence intensity. [13][14][15][16][17] Silver nanoparticles in nematic LC have improved its dielectric behaviour [18][19][20] -the nematic LC shows enhancement in luminescence [21] and variation in electro-optical parameters. [22,23] We have doped silver nanoparticles in a ferroelectric liquid crystal, because Ag nanoparticles have several optical properties.…”

Section: Introductionmentioning

confidence: 99%

Effects of silver nanoparticles doping on morphology and luminescence behaviour of ferroelectric liquid crystals Langmuir–Blodgett films

2016

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We report the deposition of Langmuir-Blodgett (LB) thin films of low-weight dispersed composite systems of ferroelectric liquid crystals (FLCs)-functionalised silver (Ag) nanoparticles. Because of their amphiphilic nature the molecules form stable Langmuir monolayers, which were transferred to silicon substrates. We noticed that absorption wave numbers are present for each bond constituting FLC-nanoparticles composite system, ensuring a complete transfer of molecules from water sub-phase. XRD showed intense peaks at 2θ = 3.2°due to the layer structure of FLC molecules. We infer from the morphology of LB films that doping of nanoparticles do not provide any hindrance to SmC Ã layer structure of FLC molecules. The photoluminescence study indicates blue shift in emission spectra and peak intensity increases with Ag nanoparticles concentration. ARTICLE HISTORY

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Electrical and electro-optical parameters of 4ʹ-octyl-4-cyanobiphenyl nematic liquid crystal dispersed with gold and silver nanoparticles

Cited by 22 publications

References 43 publications

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

Controlling the Emitter Orientation in Solution-processed Films through Introduction of Mesogenic Groups within a Multi-resonance Thermally Activated Delayed Fluorescence Emitter

Effects of silver nanoparticles doping on morphology and luminescence behaviour of ferroelectric liquid crystals Langmuir–Blodgett films

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