Regulated room temperature phosphorescence from zero-dimensional organometallic halide hybrids for anti-counterfeiting and encryption

Organometallic materials with room temperature phosphorescence (RTP) emission are of bright development prospects in optoelectronic application. Herein, we prepared two types of isostructural zero-dimensional metal-organic single crystals with RTP effect named as bis(tetraphenylphosphonium) titanium hexafluoride (Ph4P)2TiF6·2H2O and bis(tetraphenylphosphonium) zirconium hexafluoride (Ph4P)2ZrF6·2H2O. The as-prepared fluoride crystals can simultaneously emit ultraviolet (UV) fluorescence and green phosphorescent emission under 290 nm excitation at room temperature. The RTP could be observed by naked eyes for more than 6 s after removing the excited UV source. By introducing bromide ions into the crystal framework to enhance the heavy-atom effect, the photoluminescence quantum yield of the compounds dramatically boosted to 19.47%. These results provide a facile design strategy for the adjustment of efficient transient and long-lasting RTP. Furthermore, the as-prepared materials were blended in the resins and printed as the anti-counterfeiting signal labels. Therefore, this work does not only reveal the efficient RTP phenomenon in the zero-dimensional metal-organic ionic compounds, but also provide potential candidates for the realization of anti-counterfeiting technology.