Investigation on the structural, spectral, and optical properties of MAPbI3.H2O and MAPbI3 perovskite crystals for photovoltaic cells

Organic-Inorganic perovskite solar cells (PSC) have reached efficiency near to c-Si cells due to their absence of grain boundaries, low trap density, and remarkable charge transport properties. However, they suffer from electronic degradation due to various environments. Our study is an attempt to address this issue by using crystalline perovskite absorber layers in solar cells. Methyl ammonium lead iodide (MAPbI(3)) crystalline perovskite materials were prepared by conventional solution synthesis process using hydrated and nonhydrated solvents. Synthesized perovskite crystals were subjected to single-crystal X-ray diffraction and powder X-ray diffraction studies to understand the crystal system and molecular arrangements. Single-crystal X-ray diffraction study confirmed the tetragonal and monoclinic crystal structure of MAPbI(3).H2O and MAPbI(3) materials, respectively. The interactions of Pb-I, C-H, and C-N in MAPbI(3).H2O crystal were studied through their bond length and bond angles, and the results were compared with the reported MAPbI(3) crystal structure. The unit cell parameters of MAPbI(3).H2O single crystal were found to be a = 10.56(18) angstrom, b = 4.68(14) angstrom, c = 11.20(19) angstrom, alpha = gamma = 90 degrees, beta = 101.17(6)degrees, and V = 544.03(15) angstrom(3) and for the MAPbI(3) crystal a = 8.91(9) angstrom, b = 8.91(9) angstrom, c = 12.60(19) angstrom, alpha = beta = gamma = 90 degrees, and V = 998(11) angstrom(3). FT-IR and FT-Raman spectroscopic studies were carried out to understand the presence of functional groups and the effect of water molecules in the crystals. Optical band gaps of these two perovskites were found to be 1.45 eV and 1.52 eV, respectively. The conductivity studies were performed on the as-grown perovskite single crystals using solar simulator experimental setup. Initial dark and AM 1.5 light I-V test on these samples provides the information about the suitability of these perovskite single crystals for the photovoltaic applications. The investigation of the solar cell device using these perovskites is in progress.