A Yellow-Emitting Homoleptic Iridium(III) Complex Constructed from a Multifunctional Spiro Ligand for Highly Efficient Phosphorescent Organic Light-Emitting Diodes.

To suppress concentration quenching and to improve charge-carrier injection/transport in the emission layer (EML) of phosphorescent organic light-emitting diodes (PhOLEDs), a facial homoleptic iridium(III) complex emitter with amorphous characteristics was designed and prepared in one step from a multifunctional spiro ligand containing spiro[fluorene-9,9'-xanthene] (SFX) unit. Single-crystal X-ray analysis of the resulting fac-Ir(SFXpy)3 complex revealed an enlarged Ir···Ir distance and negligible intermolecular π-π interactions between the spiro ligands. The emitter exhibits yellow emission and almost equal energy levels compared to the commercial phosphor iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate (PO-01). Dry-processed devices using a common host, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl, and the fac-Ir(SFXpy)3 emitter at a doping concentration of 15 wt % exhibited a peak performance of 46.2 cd A-1, 36.3 lm W-1, and 12.1% for the current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE), respectively. Compared to control devices using PO-01 as the dopant, the fac-Ir(SFXpy)3-based devices remained superior in the doping range between 8 and 15 wt %. The current densities went up with increasing doping concentration at the same driving voltage, while the roll-offs remain relatively low even at high doping levels. The superior performance of the new emitter-based devices was ascribed to key roles of the spiro ligand for suppressing aggregation and assisting charge-carrier injection/transport. Benefiting from the amorphous stability of the emitter, the wet-processed device also exhibited respectful CE, PE, and EQE of 32.2 cd A-1, 22.1 lm W-1, and 11.3%, respectively, while the EQE roll-off was as low as 1.7% at the luminance of 1000 cd m-2. The three-dimensional geometry and binary-conjugation features render SFX the ideal multifunctional module for suppressing concentration quenching, facilitating charge-carrier injection/transport, and improving the amorphous stability of iridium(III)-based phosphorescent emitters.

General Strategy for Controlled Synthesis of NixPy/Carbon and Its Evaluation as a Counter Electrode Material in Dye-Sensitized Solar Cells.

Hydrothermal treatment of nickel acetate and phosphoric acid aqueous solution followed with a carbothermal reduction assisted phosphorization process using sucrose as the carbon source for the controlled synthesis of NixPy/C was successfully realized for the first time. The critical synthesis factors, including reduction temperature, phosphorus/nickel ratio, pH, and sucrose amount were systematically investigated. Remarkably, the carbon serves as a reducer and plays a determinative role in the transformation of Ni2P2O7 into Ni2P/C. The synthesis strategy is divided into four distinguishable stages: (1) hydrothermal preparation of Ni3(PO4)2·8H2O precursor for stabilizing P sources; (2) dimerization of Ni3(PO4)2·8H2O into more thermal stable Ni2P2O7 amorphous phase along with the generation of NiO; (3) carbothermal reduction and phosphidation of NiO into NixPy (0 ≤ y/x ≤ 0.5); and (4) further phosphidation of mixed-phase NixPy and carbothermal reduction of Ni2P2O7 into single-phase Ni2P. The resultant Ni2P, the highly active phase in electrocatalysis, was applied as counter electrode in a dye-sensitized solar cell (DSSC). The DSSC based on Ni2P with 10.4 wt.% carbon delivers a power conversion efficiency of 9.57%, superior to that of state-of-the-art Pt-based cell (8.12%). The abundant Niδ+ and Pδ- active sites and the metal-like conductivity account for its outstanding catalytic performance.

[The Design, Synthesis, Characteristics and Photoelectric Properties Research of A Bulky Steric Hindrance 9-Phenyl-Fluorene Functionalized Aniline Intermediate].

In this paper, with sulfuric acid as a catalyst and acetic acid as solution at the temperature of 120 ℃ and refluxing period for 24 hours, a sterically hindered bulky 9,9-diarylfluorene intermediate of [9-(4-anilino)-9-phenyl-fluorene] had been successfully designed and synthesized with Friedel-Crafts reaction. The molecular structure of this compound was characterized in detail with nuclear magnetic resonance hydrogen spectrum, mass spectrometry, infrared ray, and so on. Nuclear magnetic resonance hydrogen spectrum and infrared ray spectrum of the compound indicated that the characteristic functional group amino of the compound at 6.55 ppm, 3 481 and 3 385 cm-1, respectively. UV-visible and fluorescence spectra properties of 9-(4-anilino)-9-phenyl-fluorene were characterized and discussed preliminarily, respectively. The research results show that the 9-(4-anilino)-9-phenyl-fluorene with bulky steric hindrance effects has four main absorption peaks with wavelength of 243, 257, 298 and 311 nm in dichloromethane solution, respectively. Moreover, with the excitation wavelength of 308 nm, an emission spectrum curve was obtained with wavelength of 300～500 nm, which has the maximum emission peak of 328 nm with a slim peak at about 405 nm and a long tail to 500 nm. The long tail was probably attributed to the interaction of intermolecular hydrogen bonding from aniline. The appropriate scope of fluorescence emission (300~500 nm) make the compound overlap with the absorption spectra of the classic blue material Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium (Ⅲ) (FIrpic) (300~500 nm). It is possible to obtain excellent host materials through proper molecular tailoring and prepare well for high performance light-emitting device. In order to further understand the photoelectric properties of the compound, we used acetonitrile as solvent and tetrabutylammonium hexafluorophosphate as electrolyte, and the electrochemical properties of the compound was characterized with cyclic voltammetry measurements.The onset of the reduction and oxidation potential of the compound are -0.759 and 0.898 V, and the corresponding HOMO and LUMO energy levels are -5.38 and -3.72 eV, which wolud be beneficial to holes and electrons injection/transportation and further modified to be excellent host materials. All of these data would provide a useful reference for further fabrication of organic semiconductor luminescent device with high performance.

A 3-dimensional spiro-functionalized platinum(II) complex to suppress intermolecular π-π and Pt···Pt supramolecular interactions for a high-performance electrophosphorescent device.

A 3-D platinum(II)-based spirometal complex has been designed and synthesized to suppress aggregation and excimer emission. A prototype phosphorescent organic light-emitting device exhibits the high-performance orange emission with an external quantum efficiency of up to 5.2%.

Efficient two-photon-sensitized luminescence of a novel europium(III) ß-diketonate complex and application in biological imaging.

A novel europium(III) ß-diketonate complex exhibiting bright two-photon-sensitized luminescence is synthesized and applied as a two-photon-sensitized luminescent probe to stain DNA in live cells.

[Synthesis, characterization, spectroscopy and theoretical calculation of two novel carbazole derivatives].

Two novel carbazole derivatives, 3-acetyl-9-n-hexylcarbazole (AHCZ) and 3, 6- diacetyl-9-n-hexylcarbazole (DHCZ) were synthesized through Friedel-Crafts reaction. The compounds were characterized by IR spectra, 1H NMR, MS and elemental analysis. UV-visible spectra of AHCZ and DHCZ were measured and compared with those of their precursors, 9-hexylcarbazole(HCZ) and carbazole(CZ). DHCZ and AHCZ exhibited strong absorption band, revealing the extent of pi conjugation in the system. TD-DFT method was performed to analyze the electronic absorption spectra of AHCZ and DHCZ, and the calculated excitation energies and oscillator strengths were compared with the experimental results.