Naphthyl-functionalized oligophenyls: Photophysical properties, film morphology, and amplified spontaneous emission

Herein, we reported a series of deep-blue-emitting naphthyl-functionalized oligophenyls as new organic
laser active materials with tunable wavelength from 385 to 410 nm in solid state. Introduction of peripheral
naphthyl into the oligophenyls enabled the great sterical dimensions due to the prominent steric
hindrance but not destroyed the molecular conjugation. We assumed that it would suppress the p-p
stacking efficiently, driving by intermolecular interaction, to hinder crystallization in solid films.
Finally, the neat films of naphthyl-functionalized oligophenyls demonstrated amorphous state compared
to the polycrystalline state of oligophenyls. Thus, naphthyl-functionalized oligophenyls displayed high
emission quantum yield (22–35%) in solid state neat films. In addition, these molecules possessed large
oscillator strength and radiative decay rate, as predicted by the theoretical analysis. The outstanding
photophysical properties and amorphous films render naphthyl-functionalized oligophenyls a new class
of optical gain media in solid state.