Study on energy-transfer in an organic-inorganic material

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We investigated energy transfer from excitons to organic materials in an organic-inorganic quantum-well material, (C_4H_9NH_3)_2PbBr_4, which is a layered perovskite-type quantum-well material. It has inorganic well layers composed of two-dimensional network of corner-sharing [PbBr_6]^4 octahedra between organic barrier layers of alkyl ammonium chains. Excitons are tightly confined in the inorganic well layers and have extremely large binding energy (- 400 meV). Strong excitonic photoluminescence (PL) are clearly observed at 3.014 eV. On the other hand, (C_10H_7CnH_<2n+1>NH_3)_2PbBr_4 and (C_10H_7OCnH_<2n+1>NH_3)_2PbBr_4 in which naphthalene molecules are doped into organic barrier layers show little PL from the excitons but show strongly enhanced phosphorescence from the triplet state of naphthalene molecules. The PL excitation measurements have shown that the enhanced phosphorescence is caused by energy transfer from the excitons. We investigated the dynamics of the energy transfer by time-resolved PL measurements using the samples which are controlled the distance between the naphthalene molecules and the excitons.