Nucleophilic functionalization of thianthrenium salts under basic conditions

• Xinting Fan,
• Duo Zhang,
• Xiangchuan Xiu,
• Bin Xu,
• Yu Yuan,
• Feng Chen and
• Pan Gao

Beilstein J. Org. Chem. 2024, 20, 257–263, doi:10.3762/bjoc.20.26

• Abstract In recent years, S-(alkyl)thianthrenium salts have become an important means of functionalizing alcohol compounds. However, additional transition metal catalysts and/or visible light are required. Herein, a direct thioetherification/amination reaction of thianthrenium salts is realized under metal

• ]. Recently, Ritter and co-workers reported that alkylthianthrenium salts can be employed to undergo reactions with N/O-nucleophiles under photocatalytic conditions [46]. Nevertheless, additional transition metal catalysts, visible light, or electrochemical devices are required for the reported works

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• (9a, Figure 7) was reported by Wyman and co-workers [37]. Interestingly, compound 9a showed pronounced negative photochromism in benzene with the best E–Z conversion upon irradiation with yellow light (λirr > 520 nm), while in chloroform no photochromism was detected. The formation of the Z-isomer of

• underwent E–Z photoisomerization in benzene upon irradiation with yellow light and returned to E-isomer in darkness at room temperature within about 30 seconds [39]. One year later, Pummerer and Marondel attempted to reproduce this experiment and to detect the Z-isomer of N,N'-dimethylindigo 11a upon

• irradiation with orange light in several solvents [40]. However, due to the technical limitations of the spectrometer, Pummerer and Marondel were not able to detect the short-living Z-11a in aromatic solvents such as benzene, bromobenzene and pyridine. Nevertheless, the E–Z isomerization of 11a was observed

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• solution such as the specific optical rotation [31][33][37][46][57][60][61][62][63], intensity of scattered light [33][37][57][58][60][62][64] or intensity of IR bands [31] against concentration for the presence of discontinuities. The concentrations corresponding to the discontinuities found are taken as

• permeation chromatography was performed in toluene on a column (400 × 20 mm) packed with Bio-Beads S-X3 gel (200–400 mesh, Bio-Rad) using a differential refractive index detector (Knauer). TLC was carried out on Silica Gel 60 F254 plates (Merck), spots were visualized under UV light and by heating plates

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• silica gel 60 F254. Visualisation was performed with UV-light (254 nm) fluorescence quenching, and/or by staining with an 8% H2SO4 dip (stock solution: 8 mL conc. H2SO4, 92 mL EtOH), ninhydrin dip (stock solution: 0.3 g ninhydrin, 3 mL AcOH, 100 mL EtOH) and/or ceric ammonium molybdate dip (stock

• lyophilisation, 1 was obtained as a light brown/orange solid (900 mg, 90%) and required no further purification. Rf = 0.6 (EtOAc/MeOH, 2:3); [α]D +76 (c 1.0, H2O); 1H NMR (500 MHz, D2O) δ 4.92 (d, J = 3.7 Hz, 1H, H-1GalNAc), 4.46 (d, J = 7.8 Hz, 1H, H-1Gal), 4.36 (dd, J = 11.0, 3.7 Hz, 1H, H-2GalNAc), 4.24 (d, J

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• (tetraphenylporphyrin performed equally well but was harder to separate from the products) and irradiated by white LED light under an atmosphere of oxygen. It led to a mixture of unseparable regioisomeric allylic hydroperoxides 2 and 2’ (≈2:1) that were not isolated for instability reasons, but directly engaged in the

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• , the ensuing RE process yields the corresponding TCBD derivatives. The resulting TCBDs and related products exhibit strong light absorption, resulting from the intramolecular charge transfer (ICT) in the visible region; they also exhibit a rich redox chemistry [11]. In the [2 + 2] CA–RE reaction of

• emission increases when they are excited at 420 nm, resulting in white-light emission. The underlying mechanism governing these luminescence properties remains unknown. It has been established that 75 does not exhibit luminescence in its solid-state form, which is attributed to the quenching effects

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China 10.3762/bjoc.20.12 Abstract A visible-light-promoted research protocol for constructing dihydropyrido[1,2-a]indolone skeletons is herein described proceeding through a cascade cyclization mediated by trifluoromethyl

• trifluoromethyl radical source under light irradiation. Umemoto’s reagent, which is capable of releasing a trifluoromethyl radical via a photoinduced single-electron-transfer (SET) process, is usually employed to enable the trifluoromethylation of unsaturated substrates [25][26][27]. Herein, we report a protocol

• -reductive quench process (Table 1). The indole substrate 1a was chosen as a model substrate, and the reaction mixture was irradiated under 450 nm visible light for 12 h, resulting in the formation of the desired product 3a, albeit in a relatively low yield (Table 1, entry 1). Control experiments revealed

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• delivered without effect to the binding site, where the DNA-binding benzoquinolizinium ligand can then be generated as needed upon irradiation. Notably, the use of light for the activation of photo-controllable DNA ligands offers several advantages because it is easy to apply, traceless, and non-invasive

• [19]. As a result, several photoactive compounds have been developed, whose DNA-binding properties can be efficiently switched on and off by light [14][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. In addition to their DNA-binding properties some annelated quinolizinium derivatives have

Electron-beam-promoted fullerene dimerization in nanotubes: insights from DFT computations

• Laura Abella,
• Gerard Novell-Leruth,
• Josep M. Ricart,
• Josep M. Poblet and
• Antonio Rodríguez-Fortea

Beilstein J. Org. Chem. 2024, 20, 92–100, doi:10.3762/bjoc.20.10

• pressures and high temperatures [13][14][15]. We aim to shed light in these reaction mechanisms and energy profiles by using complementary methodologies as standard density functional theory (DFT) calculations and first-principles Car–Parrinello molecular dynamics (CPMD) simulations. Firstly, we have

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• and operation of loop reactors are simple. Furthermore, investment and operational costs are typically low. For these reasons, the suitability of a loop reactor was studied in this work for the photocatalytic hydrogen generation process as a potentially scalable photoreactor concept. Suitable light

• , identifying photocatalysts capable of efficient performance across broad sunlight wavelength ranges proves to be a complex endeavor [26][27][28]. Therefore, artificial light sources are typically applied for lab testing of photocatalytic reactions. Compared to conventional light sources, light-emitting diodes

• (LEDs) have plenty of advantages including long life span (up to 100 000 h), robustness, compact size, and high energy efficiency, which make LEDs very attractive as a light source for photocatalytic hydrogen generation studies [29]. In this work, a loop photoreactor for scaling up the photocatalytic

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• was observed for compound 27 was also observed for this compound. The degradation of compound 20 in the presence of light and oxygen is visible as a color change upon leaving a sample of the compound in solution in an open vial, unshielded from light (Figure S2 in Supporting Information File 1). This

• degradation was investigated by UV–vis absorption spectroscopy; the absorption spectrum was measured over time for three different samples, and a notable change in the longest-wavelength absorption maximum was only observed for the sample that was exposed to both light and oxygen (see Figures S3 and S4 in

• a light orange crystalline solid (375 mg, 1.02 mmol, 88%). mp > 250 °C; 1H NMR (500 MHz, CDCl3) δ 7.89 (s, 2H), 7.71 (d, J = 8.0, 2H), 7.59 (s, 2H), 7.42 (d, J = 8.0, 2H), 3.95 (s, 4H), 1.39 (s, 18H) ppm; 13C NMR (126 MHz, CDCl3) δ 149.8, 143.8, 142.5, 140.6, 139.5, 124.1, 122.1, 119.2, 116.3, 37.0

Preparing a liquid crystalline dispersion of carbon nanotubes with high aspect ratio

• Keiko Kojima,
• Nodoka Kosugi,
• Hirokuni Jintoku,
• Kazufumi Kobashi and
• Toshiya Okazaki

Beilstein J. Org. Chem. 2024, 20, 52–58, doi:10.3762/bjoc.20.7

• ) analysis (CPS Instruments, CPS 24000UHR (CR-39)). The shape and size of the DWCNTs in dispersion were observed by settling them on a silicon substrate, washed with acetone, and exposed to UV light for 20 minutes using an ozone cleaner (Meiwafosis, PC-450 plus) via dip-coating. The structures of DWCNTs were

• , the glass slide was washed with acetone and then irradiated with UV light for a duration of 1 hour via an ozone cleaner (Meiwafosis, PC-450 plus). Later, the substrate was coated using a bar coater (OSG SYSTEM PRODUCTS Co., LTD, Select-Roller L60, OSP-10 (bar groove pitch: 0.2 mm, depth: 24 μm)) with

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• )-5-Amino-1-benzyl-N'-(thiazol-2-yl)-1H-1,2,3-triazole-4-carboximidamide (3l). Compound 3l was obtained in 88% yield (117 mg) according to the general procedure B (NaOH: 20 mg, 0.5 mmol; amidine 1a: 77 mg, 0.5 mmol; azide 2c: 56 mg, 0.5 mmol; ethanol (2 mL)) as light yellow needles; mp 199–200 °C; 1H

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• (or (Cyc-DMBI)2) and light. Moreover, in the cases of 1d and 1e there are significant mismatches between conversion and the yields of the corresponding RH and R2 species, indicating that additional products must be formed. Indeed, in the case of 4-methylbenzyl chloride GC–MS shows a product with a

• and/or light. This may be attributable to the lower stability and greater reactivity of aryl radicals relative to that of their benzyl counterparts. Indeed, aryl radicals are known to abstract H• from THF [30][31] and presumably do so in the present reactions before any further reactions can occur

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• Organic Synthesis, Aizkraukles 21, LV-1006, Riga, Latvia 10.3762/bjoc.19.139 Abstract The pyridine-3,5-dicarbonitrile moiety has gained significant attention in the field of materials chemistry, particularly in the development of heavy-metal-free pure organic light-emitting diodes (OLEDs). Extensive

• pyridine-3,5-dicarbonitrile moiety attracted a great deal of attention in the last decade in the field of materials chemistry, precisely in the development of novel heavy-metal-free pure organic light-emitting diodes (OLEDs). Inexpensive and environmentally friendly emitters are vital for organic

• small singlet–triplet splitting and a fair photoluminescence quantum yield (PLQY). The optimized organic light-emitting diode (OLED) based on 13 wt % CPC doped in 1,3-bis(9H-carbazol-9-yl)benzene (mCP) as host exhibited maximum current efficiency, power efficiency, and external quantum efficiency (EQE

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• triphenylamine as donor and dimesitylboron as acceptor linked through a thieno[3,2-b]thiophene (TT) π-conjugated linker bearing a 4-MeOPh group, was designed, synthesized, and fabricated as an emitter via a solution process for an organic light-emitting diode (OLED) application. DMB-TT-TPA (8) exhibited

• emitter for an organic light-emitting diode through a solution process. DMB-TT-TPA (8) displayed excellent performance in both device application and photophysical properties, i.e., a maximum solution fluorescence quantum yield of 86% in THF, maximum solid-state fluorescence quantum yield of 41%, maximum

Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• , Kieselgel 60, F254, Merck) with visualization under UV light. Products were purified by silica gel flash column chromatography (0.05–0.63 mm, 230–400 mesh ASTM, E.Merck). N-Tosylimines 2a–m and 5,10-bis(pentafluorophenyl)tripyrromethane (1) were synthesized according to the previously reported literature

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• menthol. The reactions under pressure were carried out in a 150 mL pressure flask (Synthware Glass). Thin-layer chromatography (TLC) was performed using silica gel 60 F254 (Merck) plates. The spots of the materials on TLC plates were visualized by UV light at 254 nm. The reactions were monitored by TLC

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• smoothly delivered an electron donor–acceptor (EDA) complex II via coulombic interactions. Upon 456 nm blue LED light irradiation, the EDA complex II underwent a single electron transfer (SET) process, followed by subsequent decarboxylation to produce the alkyl radical intermediate A, accompanied by

• light irradiation at either 440 nm or 456 nm, and they occurred in acetone at room temperature, without the need for transition metals or organic dyes as photosensitizers. Interestingly, it was discovered that solvation played a vital role in the overall process. These findings shed light on the

• -anion catalysis under visible light irradiation, as depicted in Scheme 9. Subsequent investigations revealed that redox-active esters 3 and Katritzky salts 15 derived from amino acids could be effectively employed in decarboxylative/deaminative cross-coupling reactions [15]. These reactions enabled the

Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• purpose, three main components are needed: a photosensitizer (PS), which acts like a light-antennae harvesting system in natural photosynthesis, a catalyst (Cat.), reacting directly with CO2 after being reduced, and a sacrificial electron donor (SeD). When the involved (photo)catalysts are homogeneous

• [20][21][41]. In addition, the benzimidazolidine derivative, BIH (1,3-dimethyl-2-phenyl-benzo[d]imidazolidine) (shown in Figure 1) suited well as a sacrificial electron donor, because of its high reducing power [47]. The photocatalytic experiments were performed under 420 nm light irradiation unless

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• ), organic light-emitting diodes (OLEDs) and sensors [1][2]. Columnar liquid crystals are attractive due to their solution processability and their self-organization in highly anisotropic supramolecular architectures, which favors the mainly one-dimensional migration of charge carriers with an anisotropy of

• ) and excited with a UV lamp of 365 nm wavelength. The emission spectra were captured using an optical fiber placed close to the film to guide the light until the Ocean Optics USB4000 spectrophotometer. Time-resolved fluorescence decay curves were recorded using the technique of time-correlated single

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• concentration was carried out until a suspension convenient for filtering was obtained (not to dryness). The suspension was cooled (−18 °C), the precipitate was filtered, washed with cold petroleum ether (3 × 20 mL), and dried to give imidate 4 (10.373 g, 79%) as a very light creamy solid which was used in the

• mL) was stirred under reflux for 3 h, and cooled in refrigerator (about +6 °C). The precipitate was filtered, washed with cold EtOH (4 × 15 mL), cold ether (2 × 15 mL), and dried to give a mixture of macrocycle 5 and bis-pyrazole 6 in a ratio of 89:11 (1.858 g, very light pink solid). This mixture

• collected by filtration, the mother liquor was concentrated under vacuum. To the obtained dense oily residue was added H2O (35 mL), the resulting light pink solution was cooled (0 °C), and upon manual agitation the precipitation of product was initiated. After precipitation completed, the solid was filtered

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• organic light-emitting diodes (OLEDs) [9][10][11]. Moreover, studies involving N-acylhydrazonic derivatives have highlighted their suitability for the treatment of pathologies associated with infection and/or inflammation [12][13][14][15][16][17]. Antimicrobial activity is one of the most frequently

• beige and light-yellow solids with 78% and 44% yield, respectively. Thermal analyses between 25 and 350 °C were performed in order to verify the hydration status of the bulk. Regarding hdz-CH3, a weight loss of 9.78% from around 80 to 190 °C was observed, suggesting the presence of two crystallization

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• ), organic field-effect transistors (OFETs), organic-light emitting diodes (OLEDs) and other organic electronic technologies. Notably, the potential of quinoxaline derivatives as non-fullerene acceptors in OSCs, auxiliary acceptors and bridging materials in DSSCs, and n-type semiconductors in transistor

• processability compared to their inorganic counterparts [1][2]. Charge transport in organic semiconductors is a fundamental aspect that governs the performance and functionality of various organic semiconductor devices, such as organic solar cells (OSCs), organic field-effect transistors (OFETs), organic light

• chromophores in the development of organic light-emitting diodes (OLEDs), sensors, and electrochromic devices [8][13][14]. In this review, we have comprehensively examined the recent advancements of Qx-derived ETMs in various applications within the organic semiconductor device field over the past five to six

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• –donor (D–A–D)-type molecule and its application as a non-doped emitter in an organic light-emitting diode (OLED). The fluorophore TPECNz contains naphtho[2,3-c][1,2,5]thiadiazole (Nz) as a strong acceptor unit symmetrically functionalized with N-(4-(1,2,2-triphenylvinyl)phenyl)carbazole as a donor and

• coordinates of (0.664, 0.335)), an EQEmax of 3.32% and exciton utilization efficiency (EUE) of 47%. Keywords: ambipolar material; deep red fluorophore; hybridized local and charge transfer; naphthothiadiazole; OLED; organic light-emitting diode; Introduction Recently, organic fluorophores with efficient

• , particularly when they are applied as emitters in organic light-emitting diodes (OLEDs) [19]. Therefore, with such a constrained number of efficient emitters, the current advance of DR/NIR OLEDs largely trails behind the visible light emission OLEDs [20][21]. So far, remarkable efforts have been made in