DETERMINATION OF OPTICAL, ELECTRICAL, STRUCTURAL, AND MORPHOLOGICAL PROPERTIES OF MAPbI3 PEROVSKITE FILMS FOR PHOTOVOLTAIC APPLICATIONS

Abstract

The study presents a combined analysis of optical, electrical, structural, and morphological properties of methylammonium lead iodide (MAPbI3) thin films as solar cells. Four MAPbI 3 samples were prepared and characterized via UV Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and current-voltage (JV) measurements. Based on the optical analysis, it was established that an onset of absorption was sharp around 1.6 eV and that the coefficients of absorption (> 104 cm-1) verified the direct bandgap nature of MAPbI 3. Tauc plot extrapolation gave average optical bandgap values of 1.515 eV and this complies with most appropriate range of single-junction solar cells. The highest value of power conversion efficiency of 13.91 % was observed in the electrical characterization in a forward scan with moderate hysteretic losses that are ion migration and interfacial charge accumulation effects. It was established in the structural analysis that there was a prevalent (110) orientation as well as good crystallinity but larger values of FWHM at the higher Miller indices indicated localized lattice strain and smaller grain domain size. Morphological analysis yielded an average grain size of 196±36nm which were uniform and favorable to efficient charge transport and effective recombination. The large grain circularity and solidity also pointed to the excellent film quality that was attained by optimization of spin-coating thickness with a two step thermal annealing procedure. These results confirm the suitability of MAPbI3 regarding the usage of thin-film solar cells and elaborate on the significance of processing conditions towards the tailoring of film properties and thus the overall device performance. The study contributes to the body of knowledge regarding the determinants that contribute to enhancing efficiencies, as well as stability in perovskite-based Photovoltaics.