In this study, four emitters of blue light are synthesized by selecting pyrene with its high photoluminescence quantum yield (PLQY) as the core group and variants of the electron-donating diphenylamine (DPA) as side groups. The four compounds have different numbers, sizes, and substitution positions of alkyl groups on the DPA. Each of the four compounds when doped in OLED devices shows a high current efficiency (CE) of over 7 cd A and a high external quantum efficiency (EQE) of over 7.5%. In addition, the compounds yield electroluminescence (EL) spectra showing peaks with narrow full width at half-maximum (fwhm) values of 37-40 nm and hence indicative of high color purity. Moreover, one compound N1,N6-bis(5-( tert-butyl)-2-methylphenyl)-N1,N6-bis(2,4-dimethylphenyl)pyrene-1,6-diamine (3Me-1Bu-TPPDA), shows a very high EQE of 9.25% and a very long lifetime with an LT95 of 471 h.

realistic colors can be expressed, and the contrast can be deepened, giving a 3D immersive experience. [1] To implement higher resolution quality displays, the pixel size should be more compact and smaller. Therefore, quantum dots with only a few nanometers of particle size are very suitable for the purpose. In particular, among the quantum dots, perovskite quantum dots (PeQDs) have high quantum efficiency and narrow emission spectra (full width at half maximum, FWHM) due to low trap density, and as a result, can express more realistic colors with high color reproducibility. [2] For these reasons, PeQDs have been in the spotlight as promising next-generation display materials. Perovskites generally have an ABX 3 chemical composition and their structure and stability can be predicted by calculating the Goldschmidt tolerance factor with ionic radius. [3][4][5][6] They also have the advantages of easy color tuning through halide exchange and very short synthesis time. [7,8] Currently, perovskites have been studied in depth from bulk to nanomaterials because of their wide range of applications such as LEDs, [4,9,10] solar cells, [11][12][13] lasers, [14][15][16] sensors, [17][18][19] and other applications. However, perovskites have suffered from the serious problem of low stability because structures with the ABX 3 form have weak ionic bonds and easily decompose through moisture, heat, or light exposure. [20] Unlike general semiconductor quantum dots including CdSe [21] and InP, [22] it is difficult to build a shell on the perovskite surface. Considerable research on perovskite stability has been in progress to address these issues. Recently, Li et al. fabricated CsPbBr 3 PeQD silica/ alumina monoliths through the sol-gel reaction using inorganic precursors. [23] In addition, Sun et al. showed that the photoluminescence of PeQD synthesized using octylphosphonic acid (OPA) remained in the ambient atmosphere for 3 d. [24] Herein, we synthesized PeQDs using zinc halide (ZnX 2 ) and trioctylphosphine-oxide (TOPO) as surface capping agents to improve the stability of PeQDs. The use of ZnX 2 as a precursor has already been reported. First, Jeong et al. used ZnX 2 as a halide precursor for PeQDs and explained that the stability of the PeQDs was enhanced by the halide on the surface. [25] They Perovskite is a very promising material that is being extensively studied at the bulk and nanosize scales because it has outstanding optical properties, including high quantum efficiency and narrow emission spectra. However, perovskite has stability issues related to heat, air, and light. To overcome these, highly stable perovskite quantum dots (PeQDs) are developed using excess Zn precursor and trioctylphosphine-oxide (TOPO). In particular, it is clarified that Zn and TOPO are combined and these complexes are attached to the surface of the PeQDs through 31 P NMR. They not only have high quantum efficiency and sharp full width at half maximum values (15-30 nm) but also have improved long-term stability at high temperature. Additionall...

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Highly conductive Dy and Y co-doped bismuth oxides combined with La0.8Sr0.2MnO3−δ significantly enhanced the ORR and OER as oxygen electrodes for reversible SOCs.

Two blue fluorescent materials, m-PO-ABN and p-PO-ABN, are newly synthesized by controlling the conjugation length based on different linkages of the meta or para position between the phenanthro[9,10-d]oxazole (PO) moiety...

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A new deep-blue chromophore containing a three-dimensionally (3D) shaped CS core composed of fused chrysene and spirofluorene units is synthesized. A pair of m-terphenyl (TP) units is also substituted onto the CS core at two different sets of positions to form two additional compounds: CS-TPTP and TP-CS-TP. The TP-CS-TP compound showed the highest efficiency with an external quantum efficiency (EQE) of 3.05% and Commission Internationale de L'Eclairage coordinates (CIE) of (0.148, 0.098) corresponding to the emission of blue light. This approach for forming a new chromophore is expected to lead to the development of functional organic materials with excellent characteristics.

A new hole-transporting material, poly-2-(9Hcarbazol-9-yl)-5-(4-vinylphenyl)-5H-benzo[b]carbazole (PBCZCZ), was developed for perovskite light-emitting diodes (PeLEDs). This polymer, which is based on the benzocarbazole moiety, has good solubility in common solvents and enabled the fabrication of highly efficient multilayer perovskite devices. It has excellent film morphology and a high hole mobility of 3.67 × 10 −5 cm 2 V −1 s −1 , which made it possible to vary the device configuration. Green and sky-blue perovskite PeLEDs using PBCZCZ as the hole-transporting layer had current efficiencies and external quantum efficiencies (EQEs) of 43.90 cd A −1 and 8.67% for the green device and 9.07 cd A −1 and 4.04% for the skyblue device, respectively. The EQE of the green PeLEDs was about 2.5 times higher and that of the sky-blue PeLEDs was about 3 times higher than the device made with the commercial HTL of poly(9-vinylcarbazole) (PVK). The operational device lifetimes of the green and sky-blue PeLEDs made with PBCZCZ were about 4.1 and 4.8 times higher than the PVK-containing device, respectively.