Structural and optical properties of lead iodide nanostructure synthesized by vacuum evaporation method

Abstract

Structural and optical properties were studied as a function of films thickness for thermally evaporation PbI2 films. X-ray diffraction analysis confirmed that PbI2 films are polycrystalline having hexagonal structure. The optical absorption data indicate an allowed direct transmission with optical energy gap varies continuously from (2.15eV - 2.33 eV). The energy gap shows thickness dependence, which can be explained qualitatively by a thickness dependence of grain size through the decrease of the grain boundary barrier height with grain size. The low fluctuation in energy gap indicates that the grain size is quite small, which is finding in agreement with AFM results.