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

•We reported three naphthyl-functionalized oligophenyls with ASE characteristics.•Great sterical dimensions were obtained due to steric hindrance of bulky naphthyl.•Great sterical dimensions prompted to weaken intermolecular interaction in solid films.•Amorphous films were formed instead of crystalline films.•High photoluminescence quantum yield were observed in amorphous films.

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 π-π 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.