Abstarct: In the recent years, we have witnessed the rapid development of a brand-new, type of solar cell baxsed on organic–inorganic halide perovskite materials. The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has rapidly increased from 3.8% to 22.1% since it was first reported in 2009. For PSCs, electron transport laxyers (ETLs) play a significant role in transporting electrons and blocking holes. In the vast majority of PSCs, TiO2 is the preferred material for ETLs because of its superior electronic properties. In this research, undoped and doped (with 1 molar percent of Na, Al and Fe) TiO2 were synthesized using modified hydrothermal method for the fabrication of perovskite solar cell devices. Structural, elemental composition, surface morphological and optical properties of synthesized powder were studied using XRD, EDAX, Raman, FESEM and UV-VIS analysis techniques. According to XRD results, using modified hydrothermal method caused the growth of prefertional anatase phase with little traces of brookite phase in the synthesis of nanopowders. The synthesized nanoparticles were used as electron transport laxyer in the fabrication of perovskite solar cells. The fabricated solar cells were of n-i-p-type made with mesoporous TiO2. The fabrication processes include the preparation of FTO, coating of a compact TiO2 laxyer as a hole blocking laxyer and a mesoporous laxyer of undoped and Al and Fe doped TiO2 as electron transport laxyer, and then coating of the perovskite laxyer (CH3NH3PbI3). For the deposition of the last laxyer, two methods of single-step, two-step (by two different techniques) were utilized. In the two-step method PbI2 was coated using spin coating technique and then CH3NH3I (MAI) was coated using both spin-coating and dip-coating methods, separately. The results of three applied methods were compared. Among them, the spin-spin two-step method provided the best laxyer quality and was chosen for the fabrication of the device. Spiro-MeOTAD without any additive was used for the coating of HTL. Finally, Au was deposited using DC sputtering to be acting as the back contact electrode. Raman and UV-Vis techniques were used for the quality control of every deposited laxyer during the cell fabrication. I-V measurements revealed that the device fabricated using TiO2:Fe had the best efficiency