One-dimensional excitons in inorganic–organic self-organized quantum-wire crystals [NHimageC(I)=NHimage]imagePbIimage and [CHimageSC(=NHimage)NHimage]imagePbIimage

Optical properties of lead-iodide-based one-dimensional perovskite-type crystals [NH22C(I)=NH22]33PbI55 and [CH33SC(=NH22)NH22]33PbI55 have been investigated theoretically and experimentally. The electronic and excitonic structures are studied based on group theoretical consideration and first-principle band calculation. Strong one-dimensional anisotropy of the optical absorption spectra, large Stokes shifts (∼1.0∼1.0 eV) and huge exchange energies (∼70∼70 meV) indicate that the excitons in these crystals are one-dimensional Frenkel excitons.