Almost 10 years have passed since halide perovskite semiconducting materials have been successfully used as light absorbers in solar cells. Since then, significant advances have been made and efficiencies of almost 23% have been achieved for perovskite solar cells (PSCs) based on mesoscopic metal oxides and organic semiconductors in planar heterojunctions in either n/i/p or inverted p/i/n contact geometries. However, since both configurations, as they rely on organic layers, suffer from drawbacks like photo-I-V hysteresis and poor stability in moisture and temperature, attempts are being made over the last few years to fabricate an all-inorganic PSCs by replacing the electron transport layer (ETL) and more particularly the hole transport layer (HTL) with inorganic materials. Wide band gap ptype metal oxides like NiO, Cu2O, etc, are potential candidates as HTLs since they can have better performance than their organic counterparts, can be fabricated relatively easily, at low temperatures, on large area substrates and employing low cost fabrication techniques. In this work, we fabricated halide PSCs where the perovskite was synthesized by the spin coating-anti solvent method and the HTL was Al-doped or undoped metal oxide of NiO deposited by the Physical Vapour Deposition technique of RF-sputtering and optimized for its physical properties so as to be employed in the fabrication procedure of the PSCs having the n/i/p or the inverted p/i/n configuration. The fabrication of halide PSCs were made on FTO-coated glass substrates by spin coating. The precursor solution, based on a mixed cation perovskite (“triple cation”), containing FAI, CsI, MABr, PbI2 and PbBr2 in a DMF: DMSO solvent mixture, were spin coated sequentially in a two-step program. During the second step, the antisolvent (toluene or chlorobenzene) was dripped on the substrate in order to complete the crystallization of the perovskite and remove solvent adducts that inhibit the perovskite formation. After completion of the second step, the perovskite film is transferred on a hot plate in order to evaporate the remaining solvents. The NiO and NiO:Al HTLs were fabricated by rf sputtering by employing Ni and Ni-Al targets, respectively, in plasma containing %(Ar-O2) gases, whereas N2 was added so as to further optimize the properties of the HTLs (see Explanatory Pages below). The NiO HTLs were characterized by AFM, XRD, SEM-EDX, Hall-effect and UV-Vis-NIR spectroscopy whereas the photovoltaic behaviour of all-inorganic PSCs were characterized by dark and photo I-V, PL, and EQE. The use of low temperature fabrication procedures for the all-organic PSCs will enable the realization of stable and highly efficient PSCs on both transparent rigid substrates like glass-windows and flexible (plastic-wearable) substrates for applications in energy harvesting, health care, sensing and telecommunication (IoT).