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a) The device structures and energy level diagrams. b) Current density and luminance versus voltage (J–V–L) characteristics. c) Current efficiency–luminance–power efficiency. d) External quantum efficiency (EQE) versus current density plots (inset: EL spectra of OLEDs at 6 V).
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The development of new and easily available acceptor moieties for further expansion of the thermally activated delayed fluorecence (TADF) family becomes imperative. In this study, new donor–acceptor TADF materials are designed and synthesized via introducing quinazoline unit as a simple and efficient acceptor for the first time. This is also a typi...
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... Each of the fragments is of great interest owing to their electron withdrawing properties and use in the design of donor-acceptor small molecules displaying characteristics preferable for optical materials. The quinazoline component has been explored in the context of fundamental research [3][4][5], with some quinazoline derivatives revealed to have potential application in optoelectronics [6][7][8][9], detection of analytes [10,11], bioimaging [12], etc. [1,2,4]Triazole derivatives, in turn, are considered as blue phosphorescent, TADF emitters or host materials for OLED devices [13][14][15]. Other D-π-A-π-D structures with a triazole ring as an acceptor part show strong emission in solution and potential for optoelectronic purposes [16,17]. ...
Two series of novel [1,2,4]triazolo[4,3-c]- and [1,2,4]triazolo[1,5-c]quinazoline fluorophores with 4′-amino[1,1′]-biphenyl residue at position 5 have been prepared via Pd-catalyzed cross-coupling Suzuki–Miyaura reactions. The treatment of 2-(4-bromophenyl)-4-hydrazinoquinazoline with orthoesters in solvent-free conditions or in absolute ethanol leads to the formation of [4,3-c]-annulated triazoloquinazolines, whereas [1,5-c] isomers are formed in acidic media as a result of Dimroth rearrangement. A 1D-NMR and 2D-NMR spectroscopy, as well as a single-crystal X-ray diffraction analysis, unambiguously confirmed the annelation type and determined the molecular structure of p-bromophenyl intermediates and target products. Photophysical properties of the target compounds were investigated in two solvents and in the solid state and compared with those of related 3-aryl-substituted [1,2,4]triazolo[4,3-c]quinazolines. The exclusion of the aryl fragment from the triazole ring has been revealed to improve fluorescence quantum yield in solution. Most of the synthesized structures show moderate to high quantum yields in solution. Additionally, the effect of solvent polarity on the absorption and emission spectra of fluorophores has been studied, and considerable fluorosolvatochromism has been stated. Moreover, electrochemical investigation and DFT calculations have been performed; their results are consistent with the experimental observation.
... Furthermore, numerous 2-amino-6,7-dimethoxyquinazoline analogs are extensively employed as α 1 -adrenoceptor blockers [3,4]. In recent years quinazoline-based OLED materials have also gained attention showing great quantum efficiencies [5][6][7]. Conse-quently, ongoing efforts focus on advancing methodologies for synthesizing established quinazoline-based drugs and acquiring novel modified quinazoline derivatives for pharmaceutical or materials science purposes. ...
2-Chloro-4-sulfonylquinazolines undergo functional group swap when treated with an azide nucleophile: 1) the azide replaces the sulfonyl group at the C4 position; 2) the intrinsic azide–tetrazole tautomeric equilibrium directs the nucleofugal sulfinate from the first step to replace chloride at the C2 position. This transformation is effective with quinazolines bearing electron-rich substituents. Therefore, the title transformations are demonstrated on the 6,7-dimethoxyquinazoline core, which is present in pharmaceutically active substances. The methodology application is showcased by transforming the obtained 4-azido-6,7-dimethoxy-2-sulfonylquinazolines into the α 1 -adrenoceptor blockers terazosin and prazosin by further C2-selective S N Ar reaction and azide reduction.
... The maximum external quantum efficiency (EQE) of small molecular organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) materials have been reported to surpass 40 % [1,2]. However, the high efficiency of these OLEDs depends not only on the intrinsic photophysical properties of the emitter but also on the rather complicated vacuum-deposited multilayered device structures, which greatly increases the complexity of the manufacturing process and the cost of device fabrication [3][4][5][6][7]. Therefore, efficient solutionprocessed OLEDs containing soluble small molecule TADF emitters as a low-cost alternative have been developed. ...
... According to a previous study, TTA might be the major factor of efficiency roll-off in TADF OLEDs, [57] and thus we used TTA model to analyze the efficiency roll-off for these Spiro-PMB-DI-based devices (Fig. S18). The fitted curves based on TTA model are identical to the experimental data with correlation coefficients greater than 0.98, which confirmed that the mechanism of efficiency roll-off can be primarily attributed by the TTA [4,17,58]. The higher J 0 value of 41.82 mA cm − 2 matches with smaller efficiency roll-off for the solution-processed devices based on Spiro-PMB-DI. ...
... Some of them are reported as potential compounds in medicine with antimicrobial [20,21], antimalarial [22], and anticancer [23,24] properties. Quinazoline derivatives also have applications in agrochemistry [25,26], and due to their fluorescent effects, they are largely used in material science as OLEDs [27][28][29]. Various procedures on quinazoline ring formation can be found in the literature. The most common approaches comprise: amidation and oxidative ring closure of 2-aminobenzoic acid ...
Two novel series of symmetrical and unsymmetrical conjugates, in which 1,3,4-thiadiazole and 4-N,N-dimethylaminoquinazoline scaffolds were connected via 1,4-phenylene linker, were synthetized in high yields by Suzuki cross-coupling reactions. The elaborated protocol makes use of bromo-substituted quinazolines, boronic acid pinacol ester or diboronic acid bis(pinacol)ester of 2,5-diphenyl-1,3,4-thiadiazole, catalytic amounts of [1,10-bis(diphenylphosphino)ferrocene]dichloropalladium(II) Pd(dppf)Cl2, sodium carbonate, and tetrabutylammonium bromide, which plays the role of a phase-transfer catalyst. The structures of prepared compounds were confirmed by 1H NMR, 13C NMR, UV-VIS, IR and HRMS. For the target compounds, the fluorescence spectra were measured to determine their quantum yields and Stokes shifts. The study revealed that among the tested compounds, two highly-conjugated derivatives (8a, 9a), in which 1,3,4-thiadiazole core is connected to 4-(N,N-dimethylamino)quinazoline via a double 1,4-phenylene linker, exhibit high quantum yields of fluorescence and strong fluorescence emission.
... The presence of rotatable groups is known to be favorable for aggregation induced/enhanced emission, and some of substituted benzodiazine derivatives display these properties [17,18]. The introduction of dibenzoannulated azines in the core, as well as attaching of cyano group to the ring, were demonstrated as effective approaches to develop thermally activated delayed fluorescent (TADF) emitters [19][20][21][22]. ...
... Molecules 2022, 27, x FOR PEER REVIEW 2 of 20 of substituted benzodiazine derivatives display these properties [17,18]. The introduction of dibenzoannulated azines in the core, as well as attaching of cyano group to the ring, were demonstrated as effective approaches to develop thermally activated delayed fluorescent (TADF) emitters [19][20][21][22]. Quinazolin-4(3H)-one represents diaza-heterocycle with electronic structure similar to quinazoline core and can be used as an effective electron withdrawing fragment to design push-pull structures. ...
Design and synthesis of 2-(aryl/thiophen-2-yl)quinazolin-4(3H)-ones and 4-cyano-2-arylquinazolines with Et2N-, Ph2N- or carbazol-9-yl- electron donating fragment are described. The key photophysical properties of these compounds have been studied by UV/Vis absorption and fluorescence spectroscopy in solvents of different polarity (toluene and MeCN). 2-(Aryl/thiophen-2-yl)quinazolin-4(3H)-ones show fluorescence in blue-green region in toluene solution with quantum yields up to 89% in the case of 2-(4’-N,N-diphenylamino[1,1’-biphenyl]-4-yl)-quinazolin-4(3H)-one. Moreover, triphenylamino derivative based on quinazolin-4(3H)-one with para-phenylene linker displays the highest quantum yield of 40% in powder. The fluorescence QY of Et2N and Ph2N derivatives decrease when going from toluene to MeCN solution, whereas carbazol-9-yl counterparts demonstrate strengthening of intensity that emphasizes the strong influence of donor fragment nature on photophysical properties. 4-Cyanoquinazolines are less emissive in both solvents, as well as, in solid state. The introduction of cyano group into position 4 leads to orange/red colored powder and dual emission bands. Some molecules demonstrate the increase in emission intensity upon addition of water to MeCN solution. According to frontier molecular orbitals (HOMO, LUMO) calculations, the energy gap of 4-cyanoquinazoline decreases by more than 1 eV compared to quinazolin-4-one, that is consistent with experimental data.
... [19][20][21][22] On the other hand, the rigid and planar molecules often lead to close π-π stacking in solid states which could aggravates exciton quenching. [23,24] Molecular conjugation length which determines the lowest 3 LE states is a key factor to influence the ΔE ST values and the RISC rates. On the one hand, a short conjugation length could ensure a high-lying the 3 LE state which is necessary to achieve a small ΔE ST . ...
Thermally activated delayed fluorescent (TADF) materials have drawn widespread attentions due to their great potential for practical applications in organic light-emitting diodes (OLEDs). Deep understanding of the structure-excited state-photophysical property relationships is a key to rationally design TADF emitters. Herein, two new TADF molecules, TBP-DPXZ and TBQ-DPXZ, which consist of locked (triptycene-fused dibenzophenazine) and unlocked (triptycene-fused 2, 3-diphenylquinoxaline) electron-acceptors respectively and phenoxazine electron donors are reported. The comparative study reveals that the lock/unlock strategy could substantially manipulate the lowest locally excited (LE) and charge transfer (CT) states of these emitters via changing the acceptor strength, structural rigidity, and conjugation length, and in turn lead to significantly different photoluminescence (PL) and electroluminescence (EL) performance. It is notable that the unlocked molecule TBQ-DPXZ emits efficient green fluorescence with photoluminescence quantum yield of 91% and TADF lifetime of 3.6 μs in doped film. The doped OLED based on TBQ-DPXZ achieves an external quantum efficiency (EQE) of 25.1%, a current efficiency (CE) of 79.7 cd/ A, a power efficiency (PE) of 80.0 lm/W, and a maximum luminance of 18400 cd/m², which are better than those of the TBP-DPXZ-based device and are among the best results reported so far for green TADF-OLEDs.
... [23] For instance, the donor-π-spacer-acceptor chromophore I has been used in dye sensitized solar cells (DSCCs), [24] and the quinazoline ligated iridium complex II was used as a yellow-red light emitting phosphorescent dopant in polymer matrixed OLEDs. [25] The quinazoline moiety is a suitable electron acceptor in thermally activated delayed fluorescence (TADF) systems for high performance OLEDs, [26] and compound III was used in a pure organic molecular white light-emitting OLED with dual light emission due to conformational isomerization. [22a,27] Whereas the significance of the quinazoline molecular scaffold for pharmaceutical research is widely known, less information is available about their potential use for the development of new small-molecule fluorescent dyes. ...
2‐N‐aminoquinazolines were prepared by consecutive SNAr functionalization. X‐ray structures display the nitrogen lone pair of the 2‐N‐morpholino group in conjugation with the electron deficient quinazoline core and thus representing electronic push‐pull systems. 2‐N‐aminoquinazolines show a positive solvatochromism and are fluorescent in solution and in solid state with quantum yields up to 0.73. Increase in electron donor strength of the 2‐amino substituent causes a red‐shift of the intramolecular charge transfer (ICT) band (300–400 nm); whereas the photoluminescence emission maxima (350–450 nm) is also red‐shifted significantly along with an enhancement in photoluminescence efficiency. HOMO‐LUMO energies were estimated by a combination of electrochemical and photophysical methods and correlate well to those obtained by computational methods. ICT properties are theoretically attributed to an excitation to Rydberg‐MO in SAC‐CI method, which can be interpreted as n‐π* excitation. 7‐Amino‐2‐N‐morpholino‐4‐methoxyquinazoline responds to acidic conditions with significant increases in photoluminescence intensity revealing a new turn‐on/off fluorescence probe.
... Many representatives of this class of compound are applied in medicine as antimalarial [27], antimicrobial and anticancer agents [28][29][30], or they serve as ligands for benzodiazepine and gamma-aminobutyric acid (GABA) receptors in the central nervous system [31]. Additionally, some are applied in agrochemistry [32], and quinazoline-based nucleosides have been reported as interesting new materials exhibiting nonlinear optical or fluorescent properties, highlighting their potential use in OLEDs [33]. A wide range of synthetic procedures allow generation of the studied quinazoline derivatives, including amidation and oxidative ring closure of 2-aminobenzoic acid derivatives (e.g., 2-aminobenzonitrile [34], 2-aminobenzoic acid [35] and 2-aminobenzamide [36,37]), condensation of imidates with 2-aminobenzoic acid [38], or reacting anthranilate esters with guanidine [39][40][41]. ...
Two series of novel (symmetrical and unsymmetrical) quinazolinylphenyl-1,3,4-oxadiazole derivatives were synthesized using palladium-catalyzed Suzuki cross-coupling reactions. The presented synthetic methodology is based on the use of bromine-substituted 2-phenyl-4-N,N-dimethylaminoquinazolines and either a boronic acid pinacol ester or a diboronic acid bis(pinacol) ester of 2,5-diphenyl-1,3,4-oxadiazole. The reactions are conducted in a two-phase solvent system in the presence of catalytic amounts of [1,1′-bis(diphenylphosphino)ferrocene]-dichloropalladium(II), sodium carbonate, and tetrabutylammonium bromide, which plays the role of a phase-transfer catalyst. The luminescence properties of the obtained compounds are discussed in the context of applying these compounds in optoelectronics. Specifically, two highly-conjugated final products: N,N-dimethyl-2-phenyl-6-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)quinazolin-4-amine (8f) and 6,6′-(4,4′-(1,3,4-oxadiazole-2,5-diyl)bis(4,1-phenylene))bis(N,N-dimethylquinazolin-4-amine (9f), which contain a 1,3,4-oxadiazole moiety connected to a quinazoline ring by a 1,4-phenylene linker at the 6 position, exhibit strong fluorescence emission and high quantum yields.
... This mechanism is considered as a very promising path towards the metal-free and cost competitive efficient OLED emitters [58][59][60]. Earlier, low cost, excellent stability, high efficiency TADF emitters based on pure organic molecules were used in OLEDs, instead of using expensive rare-metal elements in phosphorescent emitters [61,62]. In recent years, TADF materials are being developed by several manufacturers. ...
Electricity consumption for lighting is over 15% world's total electricity, thereby contributing to the 5% of worldwide greenhouse gas emissions. By 2030, a 50% rise in lighting demand of the existing consumption is projected due to an increase in the global population. To address the concern of rising lighting electricity consumption, the key strategy is to develop and provide energy efficient lighting products to consumers. In this respect, the Solid-State Lighting (SSL) has the potential to offer power efficiencies that are superior to those of conventional lighting sources.
Recently, white organic light emitting devices (OLEDs) have emerged as the leading technology for the new display and lighting market which has attracted substantial attention of manufacturers, product designers, and end users. OLED devices have already entered into high end lighting markets such as designer, automotive, aerospace, high-end architectural lighting, and other applications. Moreover, innovative flexible OLED devices are thought to be candidates for the next-generation SSL systems, wearable electronics, mobile devices, microdisplays, etc. as they are lighter, thinner and more durable compared to glass (rigid) based devices.
In the present review, distinctive features of OLEDs SSL lighting, technical requirements of lighting for applications, OLED basic, and classification of OLED devices, including quantum dot (QD) OLEDs (QLED) as well as the need of development of OLEDs standards are discussed. Various constituents of flexible OLED lighting, OLED lighting panels by some manufacturers, hurdles in OLED lighting technologies, performance of OLEDs in harsh conditions, challenges in flexible OLEDs, OLED lighting technology comparison, OLED lighting roadmap, and future directions including cost reduction analysis, flexible OLED incorporated into automotive, IoT (Internet of Things) connected lighting system, OLED market projections, etc. are also presented. It is suggested that the white OLEDs, and flexible OLEDs in particular, lighting products have potential to revolutionize the future of lighting systems, industries, and the market.
... Quinazoline is a planar aromatic heterocyclic compound with the fused bicyclic structure consisting of benzene and pyrimidine rings. Quinazoline derivatives were investigated and used in medicinal applications, such as monitoring of specific biological activities and as antimalarial and anticancer agents [5,6]. However, electroactive properties of derivatives of this acceptor Scheme 1: Synthesis of quinazoline derivatives 1-3. ...
... Two blue emitters based on fluorene-bridged quinazoline and quinoxaline derivatives were used in the active layers of OLEDs with EQEs of 1.58% and 1.30%, suggesting that the self-aggregation of emitters had a considerable effect on the photoluminescent and electroluminescent properties [8]. A quinazoline-based emitter exhibiting thermally activated delayed fluorescence (TADF) was also reported [6] and green to yellow TADF OLEDs were fabricated with EQEs from 17.6 to 20.5%. The multicolor emission of a quinazoline-carbazole compound was employed in white OLEDs. ...
Three compounds, bearing a quinazoline unit as the acceptor core and carbazole, dimethyldihydroacridine, or phenothiazine donor moieties, were designed and synthesized in two steps including a facile copper-catalyzed cyclization and a nucleophilic aromatic substitution reaction. The photophysical properties of the compounds, based on theoretical calculations and experimental measurements , as well as the electrochemical and thermal properties, are discussed. The synthesized compounds form glasses with glass-transition temperatures ranging from 116 °C to 123 °C. The ionization potentials estimated by cyclic voltammetry of the derivatives were in the range of 5.22-5.87 eV. The 3,6-di-tert-butylcarbazole-substituted quinazoline-based compound forms a sky-blue emitting exciplex in solid mixture with the acceptor 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine as well as an orange emitting exciplex with the donor 4,4′,4″-tris[3-methylphenyl(phenyl)amino]triphenylamine. A white OLED based on these versatile exciplex systems with a relatively high maximum brightness of 3030 cd/m 2 and an external quantum efficiency of 0.5% was fabricated. 1142
