Visible-excitable long-afterglow material with dual-mode emission of delayed fluorescence and room temperature phosphorescence†

Abstract

A unique BA@Fluo material was successfully fabricated by reacting the classical ACQ molecule—fluorescein (Fluo)—with the interesting matrix boric acid (BA) using a one-pot method at high temperatures. Thus, the obtained material greatly expands the range of excitation wavelengths (240–460 nm), and even the LED light generated from the cellphone can be excited. In addition, the material can achieve dual-mode efficient emission of RTP and TADF. Because the two luminous modes have different responses to thermal stimulation, the emission of colorful afterglow can be achieved under the control of temperature. Additionally, BA@Fluo has a slight excitation wavelength-dependent fluorescence emission property. Particularly, the state of such a material can transfer between the amorphous and crystalline state during the process of grinding, and fluorescence discoloration occurs by grinding accordingly. Simultaneously, the non-radiative transition process can be better inhibited in the crystalline state, leading to an increase in the absolute quantum yield of photoluminescence.