Temperature-dependent time-resolved photoluminescence of (C6H5C2H4NH3)2PbX4 (X = Br and I)

This paper describes temperature-dependent time-resolved photoluminescence of two-dimensional organic–inorganic layered perovskite compounds, (C6H5C2H4NH3)2PbX4 (X = Br and I) prepared by solution-based self-assembly. (C6H5C2H4NH3)2PbX4 shows fluorescence from free-exciton even at room temperature. At low temperatures below 90 K, the Stokes-shifted fluorescence from bound excitons appears in (C6H5C2H4NH3)2PbI4. In contrast, (C6H5C2H4NH3)2PbBr4 exhibits Stokes-shifted phosphorescence from the triplet excited state to the ground state. The local structure between the organic and inorganic layers plays a prominent role in the formation of triplet excitons.