Photovoltaic and optical properties of a polymer - PbS nanocomposite

Abstract

Photovoltaic and optical properties of a polymer-PbS nanoparticles in polyvinyl alcohol (PVA) films and the effect of annealing in air at various temperatures on these properties are studied in this work. In the range of 1.0 to 3.7 eV, absorption spectra of PbS nanocomposite films are correctly fitted by five Gaussian bands peaking at 1.5, 1.84, 2.41, 3.06, and 3.58 eV. A characteristic feature of the films is the presence of green and blue luminescence with intensity maxima at 2.25 and 3.02 eV, respectively. The luminescence intensity strongly depends on the excitation energy and the annealing temperature in air. The highest intensity of the green luminescence is observed under the excitation with 2.35 eV radiation, whereas the intensity of the blue luminescence peaks under 3.46 eV excitation. After annealing at 370 K, the intensity of the green luminescence decreases a few times whereas the intensity of the blue emission increases. The photovoltaic sensitivity of the PbS nanocomposite films depends on the annealing conditions, attaining the maximum after annealing in air at approximately glass transition temperature of PVA (370 K). The spectral range of the photosensitivity of PbS nanocomposite films is wider than that of CdSe- and CuInS₂-polymer nanocomposite films.