Toward highly fluorescence and ultralow-threshold amplified spontaneous emission in ordered solid state from twin-tapered bi-1,3,4-oxadiazole derivatives

Abstract

We report several influential factors for achieving high fluorescent quantum yield and low ASE threshold from twin-tapered bi-1,3,4-oxadiazole derivatives by theoretical and experimental investigations. High fluorescence of BOXD-T3 in either apolar solvents or in the aggregating states were due to increased conjugation and a co-planar structure in the excited state, a four-level photophysical cycle between ground state and excited state, and co-planar formation of a rigid backbone with the tendency for slipped stacking. High fluorescence efficiency, high k_r value, high σ_e value, polarized and self-waveguided emissions in BOXD-T3 solution processed aligned film contributed to the ultralow ASE threshold. Extremely strong fluorescence of the microbelt-like organogel BOXD-T3 with fluorescence quantum yield of near unity was achieved. This work paves the way toward obtaining highly fluorescent and ultralow-threshold ASE in an ordered solid state from bi-1,3,4-oxadiazole derivatives.