Highly Efficient Organic Afterglow from 2D Layered Lead-Free Metal Halide in Both Crystals and Thin Films under Air Atmosphere.

Organic afterglow materials (OAMs) with lifetime longer than 0.1 s have recently received much attention for their fascinating properties meeting the critical requirements of applications in newly-emerged technologies. However, the development of OAMs lags behind for their low luminescent efficiency. Usually, enhancing the phosphorescence efficiency of organic materials causes a short lifetime. Here, we report two kinds of OAMs, 2D layered organic–inorganic hybrid Zinc bromides (PEZB-NT and PEZB-BP), obtained in an environmentally friendly ethanol solvent by low-temperature solution method. They display highly efficient and persistent luminescence at air in both crystals and thin films with phosphorescent quantum yield up to 42% in crystals, and 27% in film. For OAMs, the two quantum yields are the highest values ever reported for crystals and films, respectively. Due to the excellent crystalline and film-forming ability, PEZB-NT and PEZB-BP in ethanol can be used as ink to construct patterns in various r...