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147 results on '"Shi, Lin-Xi"'

16. Solution-Processed Organic Light-Emitting Diodes of Yellow-Emitting PtAg2Complexes with an External Quantum Efficiency of 21.7%

Author

Wang, Zhao-Yi, Zeng, Hao, Shi, Lin-Xi, Zhang, Li-Yi, Xu, Liang-Jin, Wang, Jin-Yun, and Chen, Zhong-Ning

Abstract

Yellow emission is a complementary color of blue for achieving white emission. Here, we report two yellow-emitting PtAg2heterotrinuclear complexes (1and 2) of 4-ethynyl-N,N-diphenylaniline, supported by bis(diphenylphosphinomethyl)phenylphosphine (dpmp) and bis(di-o-tolylphosphinomethyl)phenylphosphine (dTolmp), respectively. The solution-processed organic light-emitting diode based on complex 1exhibits yellow emission peaked at 567 nm with the highest current efficiency (CE) of 49.7 cd A–1and an external quantum efficiency (EQE) of 14.3%. Remarkably, the device performance of complex 2containing dTolmp with a larger steric hindrance as the supporting ligand is dramatically enhanced with the CE boosting to 69.1 cd A–1and EQE of 21.7% and, more importantly, a better color saturation of yellow emission peaked at 579 nm with the CIE of (0.49, 0.50).

Published
2021
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17. Modulating the carrier transport of PtAg2 heteronuclear complexes to attain highly efficient OLEDs with narrow-band emission.

Author

Wang, Zhao-Yi, Shi, Lin-Xi, Xu, Liang-Jin, Zhang, Li-Yi, Wang, Jin-Yun, and Chen, Zhong-Ning

Abstract

High color purity with narrow-band emission is a key factor for full-color displays. However, phosphorescent metal complexes typically exhibit broad emission with a full width at half maxima (FWHM) in the range of 80–100 nm. Here, we demonstrate a facile approach to achieve narrow-band emission by introducing electron-deficient moieties with electron-transport character into PtAg2 heteronuclear complexes. The as-synthesized PtAg2 complex 3 with dibenzo[b,d]thiophene 5,5-dioxide-3-acetylide shows extremely narrow emission with an FWHM of 25 nm in CH2Cl2 solution. The narrow-band emission is further verified by another two PtAg2 complexes containing electron-transport units such as oxadiazole (complex 4) and triphenyl-triazine (complex 5), in which the FWHM values are 26 nm for 4 and 28 nm for 5 in CH2Cl2 solution. TD-DFT studies suggest that the involvement of intra-ligand transition within an electron-deficient acetylide ligand is likely responsible for the narrow-band emission. Solution-processed OLEDs based on complex 4 exhibit excellent device performance with an FWHM of 37 nm in the electroluminescent spectrum and the highest current efficiency (CE) of 69.5 cd A−1, power efficiency (PE) of 50.5 lm W−1 and external quantum efficiency (EQE) of 18.2%. The narrow-band electroluminescence is also attained in complexes 3 and 5 with the FWHM values of 31 and 40 nm, respectively, which represent the narrowest electroluminescence for multinuclear metal complexes. This strategy of introducing electron-transport moieties not only improves the device performance but also narrows the emission width and thus enhances the color purity. [ABSTRACT FROM AUTHOR]

Published
2021
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22. Elaborate Design of Ag8Au10Cluster [2]Catenane Phosphors for High-Efficiency Light-Emitting Devices

Author

Huang, Ya-Zi, Shi, Lin-Xi, Wang, Jin-Yun, Su, Hai-Feng, and Chen, Zhong-Ning

Abstract

In this work, rational design of highly soluble and phosphorescent Ag–Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9H-carbazole (H3decz) as a rigid U-shaped ligand with a distinguished hole-transport character. The self-assembly reaction of H3decz, Au+, and Ag+generated phosphorescent Ag4Au6cluster 1(Φem= 0.22 in CH2Cl2) with H2decz–having a free ethynyl (−C≡CH) group. When the four free C≡CH groups in the Ag4Au6complex 1are further bound to four (PPh3)Au+and four (PPh3)Ag+moieties through M–acetylide linkages, the formation of Ag8Au10cluster 2not only eliminates nonradiative ethynyl C–H vibrational deactivation process but also improves dramatically the molecular rigidity so that the phosphorescent efficiency of the Ag8Au10cluster 2(Φem= 0.63) is nearly 3 times that of the Ag4Au6cluster 1. The Ag8Au10cluster structure is further rigidified using diphsophine Ph2P(CH2)4PPh2(dppb) in place of PPh3so that the phosphorescence of the Ag8Au10cluster 3(Φem= 0.77) is more efficient than that of 2. Making use of the Ag8Au10clusters as phosphorescent dopants, high-efficiency solution-processed organic light-emitting diodes (OLEDs) were achieved with current efficiency (CE) and external quantum efficiency (EQE) of 47.2 cd A–1and 15.7% for complex 2and 50.5 cd A–1and 14.9% for complex 3.

Published
2020
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24. PtAu3 cluster complexes with narrow-band emissions for solution-processed organic light emitting diodes.

Author

Natarajan, Nagarajan, Shi, Lin-Xi, Xiao, Hui, Wang, Jin-Yun, Zhang, Li-Yi, Zhang, Xu, and Chen, Zhong-Ning

Abstract

In order to develop solution-processable organic light-emitting diodes (OLEDs) with improved optical properties, PtAu3 heterometallic cluster complexes that exhibit narrow-band emission spectra were prepared through judicious molecular design. The brightly emissive PtAu3 complexes with robust chemical and thermal stability (＞290 °C) show photoluminescence quantum yields (PLQY) of 80.5% to 90.1% in doped films. The dihedral angle between the plane of the aromatic acetylide and the platinum(ii) coordination square plane exerts dramatic influence on the full width at half maximum (FWHM) of phosphorescent emission, in which the better the co-planarity, the narrower the FWHM. Theoretical studies suggest that the greater involvement of the acetylide-to-Pt 3LMCT state favors narrow-band emission. Solution-processed OLEDs based on narrow-band green emitters afford a maximum current efficiency (CE) of 38.7 cd A−1, power efficiency (PE) of 22.9 lm W−1 and external quantum efficiency (EQE) of 10.3% with an FWHM of 42 nm and CIE coordinates of (0.30, 0.61). The PtAu3 cluster complex with phenanthrene-fused carbazole-acetylide displays improved device performance due to its enhanced hole-carrier ability, with a peak CE of 62.2 cd A−1, PE of 30.3 lm W−1 and EQE of 16.6%. The elegant synthetic strategy combining electron and/or hole transport units enhances not only the device performance of the PtAu3 cluster complexes but also their charge carrier abilities, which were analyzed through space charge limited current measurements. [ABSTRACT FROM AUTHOR]

Published
2019
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27. Using phosphorescent PtAu3 clusters for superior solution-processable organic light emitting diodes with very small efficiency roll-off.

Author

Natarajan, Nagarajan, Shi, Lin-Xi, Xiao, Hui, Wang, Jin-Yun, Zhang, Li-Yi, Zhang, Xu, and Chen, Zhong-Ning

Abstract

A family of highly phosphorescent PtM3 (M = Au, Ag) aromatic acetylide cluster complexes supported with tetraphosphine and stabilized by μ-chloride were synthesized by the use of weakly luminescent mononuclear Pt(PPh3)2(C≡CR)2 (R = aryl) as precursors. The formation of PtM3 cluster complexes involves the abstraction of chloride from dichloromethane. The dramatic difference between PtAg3 and PtAu3 cluster structures arises from the location of the Pt atom, which is at the center of the triangle-planar PtM3 cluster for M = Ag whereas at one of the three corners in the PtM3 triangle plane for M = Au. Perturbation of the chloride ion in complexation by using a halide-abstracting agent results in the formation of PtM2 heterotrinuclear structures as demonstrated by X-ray crystallography. The PtAu3 complexes display intense phosphorescence with quantum yields of over 90% in doped films. High-efficiency OLEDs based on PtAu3 complexes were attained with an external quantum efficiency (EQE) over 18%. Most importantly, the optimized devices exhibit extremely small efficiency roll-off (less than 1%) at a practical brightness over 1000 cd m−2, which is one of the best performances for solution-processable phosphorescent OLEDs. [ABSTRACT FROM AUTHOR]

Published
2018
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