Strong excitonic effect in organic-inorganic hybrid crystals

► We calculate dielectric function of ZnTe(C2H8N2)0.5 including excitonic effect. ► Excitonic wave function is confined within the optical active ZnTe layer. ► Excitonic effect is so strong that the RPA spectra are changed completely. ► Binding energies are 0.54 and 0.42 eV for α and β structures, respectively.