Pressure dependence of phosphorescence through energy transfer from inorganic quantum well to naphthalene chromophore in (C10H7C2H4NH3)2PbCl4

The organic-inorganic hybrid quantum well compound, (C10H7C2H4NH3)2PbCl4, exhibits enhanced phosphorescence due to the energy transfer from the excitonic state of inorganic quantum well to the triplet state of naphthalene chromophore. In the present study, photoluminescence and optical absorption spectra of (C10H7C2H4NH3)2PbCl4 were investigated under pressure to 6.5 GPa in order to investigate the pressure dependence of the energy transfer. The phosphorescence intensity decreases with pressure up to 5 GPa, while the energy of the triplet state of naphthalene chromophore does not change with pressure. From the absorption spectra under pressure, it is found that the exciton energy of inorganic quantum well decreases with pressure up to 5 GPa. In our experiment, the energy transfer from the singlet state of naphthalene chromophore exited by ultraviolet light at 3.82 eV to the singlet exciton of inorganic quantum well occurs, and then the singlet exciton is converted to the triplet exciton by intersystem crossing, which is followed by the energy transfer to the triplet state of naphthalene chromophore for phosphorescence. Our observations on phosphorescence can be explained by a change in the energy difference between the excitonic state of inorganic quantum well and the singlet state of naphthalene chromophore with pressure.