Pure organic electrophosphorochromism system

Electrochromic phosphorescent materials have recently attracted much attention, however, achieving the efficient electrophosphorochromism in pure organic materials is highly challenging and has not been reported yet. Herein, a kind of pure organic host-guest system (BA@CzPA) is constructed by one-pot in-situ melt blending of (9-phenyl-9H-carbazol-2-yl)boronic acid (CzPA) and boric acid (BA). Because of the efficient intersystem crossing promoted by covalent, hydrogen bonding, and confinement effect, the proposed BA@CzPA exhibit the superior room temperature phosphorescence (RTP) efficiency, including an ultralong lifetime of up to 4.23 s and a high phosphorescent quantum yield of 10.9 %. Importantly, the BA@CzPA have a unique electrophosphorochromism property, and their electrically-induced RTP emission can gradually red-shift from 440 nm to 548 nm as the current density increases, which is attributed to the transformation of host matrices of BA@CzPA from metaboric acid to B₂O₃ under the electrical stimuli. This finding provides us not only with a new idea to develop pure organic electrophosphorochromism materials with high RTP efficiency, but also with a powerful strategy to fabricate correlation color temperature tunable white light emitting diodes.