Two-dimensional Wannier excitons in a layered-perovskite-type crystal (C6H13NH3)2PbI4

Wannier series excitons have been identified by electroabsorption and two-photon absorption spectroscopy on a layered-perovskite-type crystal (C6H13NH3)2PbI4. 1s, 2s, 2p, 3p excitons are located at 2.34, 2.60, 2.61, and 2.64 eV, respectively. This finding indicates the excitons in this system exhibit a relatively strong two-dimensional character. The large binding energy of the 1s exciton (>300 meV) is considerably enhanced by the dielectric confinement effect.