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...

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.

No abstract