Solution-processable naphthalene and phenyl substituted carbazole core based hole transporting materials for efficient organic light-emitting diodes

Kumar, Sudhir; An, Chih-Chia; Sahoo, Snehasis; Griniene, R.; Volyniuk, Dmytro; Grigalevičius, Saulius; Jou, Jwo‐Huei

doi:10.1039/c7tc03049e

Cited by 44 publications

(20 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This gives carbazole and its derivatives optical and electronic properties well suited for use in emissive devices based upon organic molecules. Carbazole has great synthetic versatility permitting systematic variations through substitution, interconversion and coupling reactions, allowing optimisation of the optoelectronic properties of carbazole derivatives for many applications [1–11] . Among the most important of these applications are their use as hole transport materials (HTMs), [12] or as host materials in the emissive layer (EML) of organic light emitting diodes (OLEDs) [13–17] .…”

Section: Introductionmentioning

confidence: 99%

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials

Wright

Danos

Montanaro

et al. 2021

Chemistry A European J

View full text Add to dashboard Cite

A series of four heterocyclic dimers has been synthesized, with twisted geometries imposed across the central linking bond by ortho‐alkoxy chains. These include two isomeric bicarbazoles, a bis(dibenzothiophene‐S,S‐dioxide) and a bis(thioxanthene‐S,S‐dioxide). Spectroscopic and electrochemical methods, supported by density functional theory, have given detailed insights into how para‐ vs. meta‐ vs. broken conjugation, and electron‐rich vs. electron‐poor heterocycles impact the HOMO–LUMO gap and singlet and triplet energies. Crucially for applications as OLED hosts, the triplet energy (ET) of these molecules was found to vary significantly between dilute polymer films and neat films, related to conformational demands of the molecules in the solid state. One of the bicarbazole species shows a variation in ET of 0.24 eV in the different media—sufficiently large to “make‐or‐break” an OLED device—with similar discrepancies found between neat films and frozen solution measurements of other previously reported OLED hosts. From consolidated optical and optoelectronic investigations of different host/dopant combinations, we identify that only the lower ET values measured in neat films give a reliable indicator of host/guest compatibility. This work also provides new molecular design rules for obtaining very high ET materials and controlling their HOMO and LUMO energies.

show abstract

Section: Introductionmentioning

confidence: 99%

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials

Wright

Danos

Montanaro

et al. 2021

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Structures of the diaryl-substituted compounds (Cx), which were used to form the hole-transporting layers (HTLs) in OLED devices, are shown in Scheme 3. The target compounds C1-C14 [44][45][46][47][48] and C17-C26 [49][50][51][52][53][54] were obtained under the conditions of the Suzuki reaction. Compounds C15-C16 were generated by the Diels-Alder reaction between conjugated diene and substituted alkene, forming the substituted cyclohexene fragments [55].…”

Section: Diaryl(diarylamino)-substituted Carbazoles As Charge-transporting Layer Materials For Oledsmentioning

confidence: 99%

2,7(3,6)-Diaryl(arylamino)-substituted Carbazoles as Components of OLEDs: A Review of the Last Decade

Kručaitė

Grigalevičius

2021

Materials

Self Cite

View full text Add to dashboard Cite

Organic light emitting diode (OLED) is a new, promising technology in the field of lighting and display applications due to the advantages offered by its organic electroactive derivatives over inorganic materials. OLEDs have prompted a great deal of investigations within academia as well as in industry because of their potential applications. The electroactive layers of OLEDs can be fabricated from low molecular weight derivatives by vapor deposition or from polymers by spin coating from their solution. Among the low-molar-mass compounds under investigation in this field, carbazole-based materials have been studied at length for their useful chemical and electronic characteristics. The carbazole is an electron-rich heterocyclic compound, whose structure can be easily modified by rather simple reactions in order to obtain 2,7(3,6)-diaryl(arylamino)-substituted carbazoles. The substituted derivatives are widely used for the formation of OLEDs due to their good charge carrier injection and transfer characteristics, electroluminescence, thermally activated delayed fluorescence, improved thermal and morphological stability as well as their thin film forming characteristics. On the other hand, relatively high triplet energies of some substituted carbazole-based compounds make them useful components as host materials even for wide bandgap triplet emitters. The present review focuses on 2,7(3,6)-diaryl(arylamino)-substituted carbazoles, which were described in the last decade and were applied as charge-transporting layers, fluorescent and phosphorescent emitters as well as host materials for OLED devices.

show abstract

“…Developing a suitable host material is highly essential to pose following properties as (1) appropriate frontier energy-levels HOMO/LUMO for aligning host-guest molecules, helping in the formation and harvesting the radiative excitons in the emissive region, (2) efficient triplet energy-level corresponding to the guest molecules, assuring complete energy transfer from host to guest materials, (3) efficient charge transfer capabilities, improving the charge transfer and charge recombination in the host-guest system, and (4) high glass-transition temperature and thermal-decomposition temperatures to attain good thin-films morphology to realize highly stable organic LEDs. The carbazolyl, indolyl, and phenothiazinyl chromophores display enormous triplet energies and appropriate host materials for the dry-processed organic LED devices [20,[30][31][32][33]. However, they encounter problems in solution-processed organic LEDs, inspiring us to search for novel solutionprocessable host materials with desired characteristics.…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient Candlelight Organic Light-Emitting Diode with a Very Low Color Temperature

et al. 2021

Self Cite

View full text Add to dashboard Cite

Low color temperature candlelight organic light-emitting diodes (LEDs) are human and environmentally friendly because of the absence of blue emission that might suppress at night the secretion of melatonin and damage retina upon long exposure. Herein, we demonstrated a lighting device incorporating a phenoxazine-based host material, 3,3-bis(phenoxazin-10-ylmethyl)oxetane (BPMO), with the use of orange-red and yellow phosphorescent dyes to mimic candlelight. The resultant BPMO-based simple structured candlelight organic LED device permitted a maximum exposure limit of 57,700 s, much longer than did a candle (2750 s) or an incandescent bulb (1100 s) at 100 lx. The resulting device showed a color temperature of 1690 K, which is significantly much lower than that of oil lamps (1800 K), candles (1900 K), or incandescent bulbs (2500 K). The device showed a melatonin suppression sensitivity of 1.33%, upon exposure for 1.5 h at night, which is 66% and 88% less than the candle and incandescent bulb, respectively. Its maximum power efficacy is 23.1 lm/W, current efficacy 22.4 cd/A, and external quantum efficiency 10.2%, all much higher than the CBP-based devices. These results encourage a scalable synthesis of novel host materials to design and manufacture high-efficiency candlelight organic LEDs.

show abstract

Solution-processable naphthalene and phenyl substituted carbazole core based hole transporting materials for efficient organic light-emitting diodes

Abstract: Solution-processable molecular hole transporting materials (HTMs) are crucial to realize inexpensive fabrication of energy-efficient and large area organic light emitting diodes (OLEDs) for next-generation displays and lighting.

Cited by 44 publications

References 48 publications

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials

2,7(3,6)-Diaryl(arylamino)-substituted Carbazoles as Components of OLEDs: A Review of the Last Decade

Highly Efficient Candlelight Organic Light-Emitting Diode with a Very Low Color Temperature

Contact Info

Product

Resources

About