Abstract
Abstract This study demonstrates that the use of bilayer films based on nickel oxide (NiO x ;) and cobalt phthalocyanine (CoPc) represents a promising hole transport layer (HTLs) for inverted perovskite solar cells (PSCs). NiO x ; films are fabricated using the spin‐coating method from a sol–gel solution. Films (CoPc evap ) and nanowires (CoPc nws ) on the NiO x ; surface are produced by thermal sputtering and physical gradient‐temperature vapor deposition. It is demonstrated that PSCs with a NiO x ; layer exhibit a power conversion efficiency (PCE) of only 18,1%. The incorporation of a CoPc evap intermediate layer between NiO x ; and the perovskite increases the PCE to 19.1%. The highest PCE, reaching 20.7%, is achieved with a bilayer HTLs based on NiO x ;/CoPc nws . Analysis of the PSC impedance spectra shows that the CoPc nws intermediate layer reduces the HTLs resistance and increases the recombination resistance at the perovskite/HTLs interface, which extends the effective lifetime of charge carriers. The stability of NiO x ;‐based PSCs is 48%, while PSCs with bilayer HTLs based on NiO x ;/CoPc nws and NiO x ;/CoPc evap exhibits higher stability of 71% and 90% over 600 hours. The results demonstrated that solar cells based on NiO x ;/CoPc inhibit the perovskite degradation process and reduce charge recombination, thereby improving the performance and stability of the inverted PSCs.