Excitonic luminescence in the self assembled organic-inorganic quantum well crystal: (C4H3SC2H4-NH3)2[PbI4]

In this article we focus on the optical properties of a luminescent two-dimensional organic-inorganic material (thiopheneethyl ammonium lead iodide) with the formula (C4H3SC2H4NH3)2[PbI4]. This compound exhibits a self-assembled nano-layered structure, forming a multi-quantum wells (QWs) structure. X-ray diffraction patterns revealed that thin films deposited by a spin coating method were highly oriented with the c-axis perpendicular to the substrate surface. The optical properties were investigated by, absorption, ellipsometry and photoluminescence spectroscopy. At room temperature a strong photoluminescence, due to exciton confined in the PbI quantum well, is found around 2.32 eV. The Stokes shift was determined and compared with those found for homologous materials. The exciton-phonon interaction was also investigated by studying the temperature dependence of photoluminescence. The exciton-phonon coupling constants for both acoustic and optical phonons were extracted using a phenomenological model are more than one order of magnitude larger than in conventional QWs.