Ultrafast dynamics of a highly-emissive zero-dimensional organic tin bromide perovskite

• A 0D tin bromide perovskite with near-unity emission quantum yield was reported. • Different crystallization rate leads to different crystal phases for tin bromides. • The ultrafast dynamics was revealed by fs TA spectroscopy. • A fast ISC process with time constant of 571 fs was observed in the fs TA spectra. A zero-dimensional (0D) yellow emissive tin bromide perovskite with near-unity photoluminescence quantum yield (PLQY) was synthesized. The ultrafast excited-state dynamics of the yellow emissive perovskite was investigated by using femtosecond transient absorption spectroscopy. Two ultrafast dynamics processes, intersystem crossing (ISC) from a dark singlet self-trapped exciton (STE) state to a triplet STE state with time constant of 571 fs, and a cooling of a hot triplet STE state with time constant of 28.6 ps were unveiled. A clear mechanism depicting the growth and decay pathways of STEs in the 0D assembly was provided.