Aminonaphthalic Anhydrides as Red-Emitting Materials: Electroluminescence, Crystal Structure, and Photophysical Properties

Red emissive AIE luminogens with high hole-transporting properties for efficient non-doped OLEDs

Two bifunctional red AIE luminogens with efficient solid-state emission and good hole-transporting characteristics are reported. Efficient non-doped OLEDs are fabricated with high external quantum efficiencies of up to 3.9%. Bilayer EL devices using them as both EMLs and HTLs are fabricated with good performances.

A theoretical study on photophysical properties of triphenylamine-cored molecules with naphthalimide arms and different π-conjugated bridges as organic solar cell materials

Theoretical investigations show that star-shaped molecules are expected to be promising candidates for charge transfer and donor materials for OSCs.

Fluorescence Spectroscopic Properties and Crystal Structure of a Series of Donor−Acceptor Diphenylpolyenes

A series of p-nitro-p'-alkoxy(OR)-substituted (E,E,E)-1,6-diphenyl-1,3,5-hexatrienes (1a, R = Me; 1b, R = Et; 1c, R = n-Pr; 1d, R = n-Bu) were prepared. The absorption and fluorescence spectra in solution were almost independent of the alkoxy chain length. The absorption maximum showed only a small dependence on the solvent polarity, whereas the fluorescence maximum red-shifted largely as the polarity increased. The solid-state absorption and fluorescence spectra were red-shifted relative to those in low polar solvents and were clearly dependent on the alkoxy chain length. The fluorescence maxima for the crystals of 1b and 1d were observed at 635-650 nm, which were red-shifted by 40-50 nm relative to those for 1a and 1c. The Stokes shifts were all relatively small (3000-3500 cm-1). For all four compounds, the fluorescence decay curves in the solid state were able to be analyzed by single-exponential fitting to give the lifetimes of 1.1-1.3 ns. This indicates that the emission of 1a-d is not originated from an excimer or molecular aggregates, but from only one emitting monomeric species. The fluorescence quantum yields of 1a-d were considerably high compared with the values for organic solids, which is consistent with their monomeric origin of emission. Single-crystal X-ray structure analyses of 1a, 1c, and 1d showed that the crystal packing was dependent on the alkoxy chain length. The crystals of 1a and 1c had herringbone structure, whereas that of 1d had pi-stacked structure. Strong pi-pi interaction in the crystal of 1d would be the cause of the spectral red shifts relative to those for 1a and 1c. No observation of excimer fluorescence from crystal 1d can be attributed to the limited overlap between the pi-planes of the molecules due to its "slipped-parallel" structure.