Electronic and Excitonic Structures of Inorganic-Organic Perovskite-Type Quantum-Well Crystal (C_4H_9NH_3)_2PbBr_4

摘要

The electronic and excitonic structures of an inorganic-organic perovskite-type quantum-well crystal (C_4H_9NH_3)_2PbBr_4 have been investigated by optical absorption, photoluminescence, electroabsorption, two-photon absorption, and magneto-absorption spectroscopies. Excitons in (C_4H_9NH_3)_2PbBr_4 are of the Wannier-type, and ns (n ≥ 2) excitons form an ideal two-dimensional Wannier exciton system. The binding energy, longitudinal-transverse splitting energy, and exchange energy of 1s excitons have been determined to be 480, 70 and 31 meV, respectively. These high values originate from both a strong two-dimensional confinement and the image charge effect. These values are larger than those in (C_6H_(13)NH_3)_2PbI_4, owing to the smaller dielectric constant of the well layer in (C_4H_9NH_3)_2PbBr_4 than that in (C_6H_(13)NH_3)_2PbI_4. The seemingly unusual electric-field dependence of excitons resonance is also reasonably understood by taking the image charge effect into account.