Obtaining long-term thermally stable via low-cost inorganic-hole extraction layer (i-HEL) is the best choice towards the commercialization of thermo-stable, low-cost perovskite solar cells (PSCs). In the present investigation we have developed a simple method for p-type cesium doped NiOx (Cs:NiOx) an active interfacial layer between perovskite and CuSCN i-HEL towards thermally stable low-cost PSCs. Cs:NiOx nanoparticles were synthesized by simple solution method followed by spin-coating between perovskite and CuSCN interface for mesoscopic regular (n-i-p) type PSCs. The developed method is not only protecting perovskite layer from polar diethyl sulfide solvent but also extract holes efficiently. The best efficiency based on Cs:NiOx/CuSCN double i-HEL devices exhibited 18.42% with >95% thermal stability over 1000 hours at 60 degree Celsius. Interestingly, NiOx/CuSCN and Cs:NiOx/CuSCN double i-HEL based devices are much stable either conventional spiro-MeOTAD or single i-HEL based PSCs due to perfect isolation of the perovskite layer from polar solvent.