Tuning the Energy Level and Photophysical and Electroluminescent Properties of Heavy Metal Complexes by Controlling the Ligation of the Metal with the Carbon of the Carbazole Unit

Abstract

Four novel IrIII and PtII complexes with cyclometalated ligands bearing a carbazole framework are prepared and characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Single‐crystal X‐ray diffraction studies of complexes 1, 3, and 4 reveal that the 3‐ or 2‐position C atom of the carbazole unit coordinates to the metal center. The difference in the ligation position results in significant shifts in the emission spectra with the changes in wavelength being 84 nm for the Ir complexes and 63 nm for the Pt complexes. The electrochemical behavior and photophysical properties of the complexes are investigated, and correlate well with the results of density functional theory (DFT) calculations. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ3/LiF/Al can attain very high efficiencies.

Luminescent Organoplatinum(II) Complexes with Functionalized Cyclometalated C^N^C Ligands: Structures, Photophysical Properties, and Material Applications

“…Similar observations have been found in cyclometaled iridiumA C H T U N G T R E N N U N G (III) complexes containing carbazole units. [18] Emission enhancement of 6 a-9 a in non-degassed DMSO: In the course of studying solvent effect on the emission properties of [(L [2][3][4][5][6][7][8][9] ) -9 a), we observed that the emissions of 6 a-9 a were enhanced by about 10 times, in each case, upon standing in DMSO after a period of 4 hours in air. For 2 a-5 a, their emissions were enhanced by 2-5 times after a period of 18 h under the same conditions.…”

Strong Luminescent Iridium Complexes with CˆN=N Structure in Ligands and Their Potential in Efficient and Thermally Stable Phosphorescent OLEDs

“…Due to this intrinsic factor, although abnormal cases exist, [6,7] the internal quantum efficiency (IQE) of OLEDs employing fluorescent emitters is generally limited to 25%, while IQE of OLEDs utilizing phosphorescent emitters (PHOLEDs) can reach almost 100%. [3] Hence, due to this higher efficiency and motivated by the potential applications in flat panel displays (FPDs), solid-state lighting (SSL), and backlights for liquid-crystal displays (LCDs) based on OLED technology, PHOLED materials and devices have been intensively studied since the seminal work in 1998.[3] Great success has been achieved in device efficiency, [8][9][10][11] color tuning, [12][13][14] and also white-light emission. [15][16][17] In contrast, lifetimes of PHOLEDs have been less explored, and need to be further improved.…”

Highly Efficient Red Phosphorescent OLEDs Based on Ir(III) Complexes with Fluorine-substituted Benzoylphenylpyridine Ligand

“…1,27 Their emission quantum yields were 0.36, 0.26, 0.36 and 0.28, respectively, as determined using Ir(ppy) 3 (0.40) used as the reference. 28 The respective HOMO energy levels of 1-4 were measured at -5.68, -5.86, -5.77 and -5.51 eV by low-energy photoelectron spectrometer (Riken-Keiki AC-2). The optical energy band gaps (E g ) of 1-4 were 2.25 -2.49 eV, as determined from the absorption spectra.…”

“…6,7 Ir(III) complexes are the most popular electrophosphorescent emitting materials owing to their high efficiency and facile color tuning compared. [8][9][10] Recently, a variety of Ir(III) complexes have been developed as electrophosphorescent emitters. [11][12][13] Among those are Ir(III) complexes based on the carbonylated phenyl-pyridine ligands.…”