Studies on CH3NH3PbI3 prepared by low-cost wet chemical technique

Methylammonium lead iodide (CH3NH3PbI3) has attracted tremendous attention in solar cell development due to its direct band gap, similar to 1.50 eV and high optical absorption coefficient, similar to 10(4)-10(5) cm(-1). CH3NH3PbI3 samples were synthesized using a low-cost wet chemical technique and studied their structural, optical, morphological, compositional and thermogravimetric properties. X-ray diffraction pattern of CH3NH3PbI3 revealed a single phase with tetragonal crystal structure; however, the orientation strongly depended on the heating of the sample. Raman spectra exhibited the bending and stretching bonds of Pb-I around 62 and 94 cm(-1), respectively, in all samples. The chemical functions of C-H and N-H stretching, C-H and N-H bends, O-H stretch and C-H rock and twist bonds were detected in FTIR spectra. A systematic bond shift revealed higher wavenumber upon increasing the drying temperature demonstrates the growth of stable material. A sharp band edge observed around 1.5 eV confirmed the synthesis of less defective material suitable for high efficiency solar cell development. The content of Pb and I with a desired stoichiometry was determined with EDS measurement. Thermogravimetric analysis demonstrates no weight loss in CH3NH3PbI3 samples up to 220 degrees C.