[en] Highlights: • TiO_2 blocking layer (BL) was synthesized using various methods. • Effect of BL characteristics on performance of perovskite solar cell was studied. • Charge transfer kinetics of perovskite solar cells with different BLs was explored. • We demonstrated efficient solar cells employing chemical bath deposition based BLs. - Abstract: Organolead trihalide perovskite materials have been successfully used as light absorbers in efficient photovoltaic (PV) cells. Cell structures based on mesoscopic metal oxides and planar heterojunctions have already demonstrated very impressive and brisk advances, holding great potential to grow into a mature PV technology. High power conversion efficiency (PCE) values have been obtained from the mesoscopic configuration in which a few hundred nano-meter thick mesoporous scaffold (e.g. TiO_2 or Al_2O_3) infiltrated by perovskite absorber was sandwiched between the electron and hole transport layers. A uniform and compact hole-blocking layer is necessary for high efficient perovskite-based thin film solar cells. In this study, we investigated the characteristics of TiO_2 compact layer using various methods and its effects on the PV performance of perovskite solar cells. TiO_2 compact layer was prepared by a sol-gel method based on titanium isopropoxide and HCl, spin-coating of titanium diisopropoxide bis (acetylacetonate), screen-printing of Dyesol’s bocking layer titania paste, and a chemical bath deposition (CBD) technique via hydrolysis of TiCl_4, respectively. The morphological and micro-structural properties of the formed compact TiO_2 layers were characterized by scanning electronic microscopy and X-ray diffraction. The analyses of devices performance characteristics showed that surface morphologies of TiO_2 compact films played a critical role in affecting the efficiencies. The nanocrystalline TiO_2 film deposited via the CBD route acts as the most efficient hole-blocking layer and achieves the best performance in perovskite solar cells. The CBD-based TiO_2 compact and dense layer offers a small series resistance and a large recombination resistance inside the device, and makes it possible to achieve a high power conversion efficiency of 12.80%.