Tailoring of energy levels in lead chloride based layered perovskites and energy transfer between the organic and inorganic planes

Excitonic inter-layer energy transfer is proved in a system consisting of bimolecular layers of organic dyes (benzyl, naphthyl, or anthryl) in lead chloride perovskites. By a systematic variation of the dye molecules we place the inorganic exciton band of lead chloride energetically beneath, above or between the singlet and triplet levels of the dye. Therefore we observe emission from that exciton band, the molecular singlet or triplet level due to energy transfer between the inorganic and organic layers. In the case of the layered perovskite (C6H5–CH2-NH3)2PbCl4 we succeeded in energetically matching the inorganic exciton band with the molecular triplet level.