No abstract

This article describes the synthesis and characteristics of a cyanofluorene–acetylene conjugate based blue emitter C3FLA-2. In the host doped device, C3FLA-2 shows an EQE of 8.0% and CIExy of (0.156, 0.048).

A series of thienylphenothiazine decorated carbazoles were synthesized and characterized by optical, electrochemical, thermal, and theoretical investigations. Absorption spectra of the compounds are influenced by the substitution pattern and chromophore number density. Compounds containing 2,7-substitution exhibited red-shifted absorption, while the chromophore loading on the other positions led to the increment in molar extinction coefficients due to the increase in the chromophore density. Multiple substitutions resulted in twisting of chromophores and affected the conjugative delocalization of the π-electrons, which produced shorter wavelength absorption for the 2,3,6,7-tetrasubstituted derivative. Interestingly, the compounds exhibited excited-state solvatochromism attributable to the structural reorganization-induced electronic perturbations. The solvatochromic data are supportive of a general solvent effect, which is further confirmed by Lippert-Mataga correlation. End-capping with butterfly shaped phenothiazine restrained the formation of molecular aggregates in the solid state. All of the compounds displayed exceptional thermal stability attributable to the rigid carbazole building block. Solution processed OLED fabricated using the new materials as emitting dopants in 4,4'-bis(9H-carbazol-9-yl)biphenyl host exhibited bluish green electroluminescence.

Polymeric composite films with a high loading of nano-size silicates can hardly meet the increasingly stringent fireproof and smoke-free requirements during burning. Thus, it is desirable to prepare pure clay films that can block air, heat, and flame. Here we report an organic-free clay film capable of both flame- and heat-shielding. The film was prepared from the self-assembly of nanometer-thick silicate platelets derived from the exfoliation of natural clays. The self-assembled film has a highly regular multilayered nanostructure over a large area and an appreciable volume of air entrapped in between. The combination of regular structure and substantial air volume contributes to the low thermal conductivity and flame blocking property of the film. It was demonstrated that the film can shield flame over hour duration and prevent temperature rising on the backside of film. This remarkable clay film has a myriad of uses including gas barrier, heat insulator, and fireproof devices.

No abstract