Inserção de óxido de grafeno em fotoeletrodos de ZnS crescidos sobre ZnO

Abstract

The use of non-renewable energy sources has caused several impacts on the environment, and for the world to develop healthily and sustainably, the use of renewable energy is necessary. Solar energy is a clean energy that has been standing out and getting more space, mainly due to its easy applicability and the new technologies that are emerging. Thus, the objective of this study is improve the efficiency of a dye-sensitized solar cell (DSSC) of the ZnO/ZnS through the incorporation of graphene oxide in the structural matrix, improving electron conductivity and dye adsorption on the surface of the material, to minimize the recombination process. For this, ZnO/ZnS was synthesized by the micro-wave assisted hydrothermal method, and graphene oxide, supplied by the GQMate research group (UFSM), was inserted into the matrix during the ZnO coating process, interacting with electromagnetic waves during the process. A DSSC was assembled using the doctorblade

method for the preparation of photo-electrodes, the counter-electrodes were made of platinum, and cells were assembled with both the N3 dye and N719 to evaluate the photovoltaic efficiency values. For the characterizations, X-ray diffraction, Scanning Electron Microscopy, Raman spectroscopy, Infrared spectroscopy, UVvisible

spectroscopy, Photoluminescence spectroscopy, J x V electrical measurements, and electrochemical impedance were carried out. The structural and morphological results indicated the presence of the proposed structural matrix, ZnO/ZnS + OG, with the presence of vibrational modes related to the compounds, as the presence of functional groups specific to graphene oxide. In optical measurements a decrease in the materials bandgap from 3.14 eV to 2,3 eV was identified from the sample without graphene oxide and to the sample with the highest amount (4%). The results about electrical measurements demonstrate the potential of using reduced graphene oxide in the photovoltaic field, presenting significant improvements in shorcircuit current density (J SC ) and solar cell efficiency.