Resonance effects of Wannier-Frenkel excitons in luminescence properties of layered perovskite compounds (C₆H₅CH₂NH ₃)₂PbCl_xBr_4-x

To analyze the luminescence properties under resonance between inorganic-organic layers, (C₆H₅CH₂NH ₃)₂PbCl_xBr_4-x thin films was fabricated. The Wannier exciton level in inorganic layer has been tuned to triplet excited levels in benzylamine in layered perovskite-type compounds by changing the halogen composition in the inorganic layer. When the Wannier exciton level was higher than the triplet state of benzylamine, energy transfer from the former to the latter occurred. The phosphorescence peak at 3.59 eV was sharpened and enhanced in the films with x = 3.75 and 3.80, and this effect can be ascribed to the enhancement of an electronic transition due to the resonance between the organic and inorganic layers.