| dc.description.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. | en_US |
