Efficient Inverted Planar Perovskite Solar Cells Using Ultraviolet/Ozone‐Treated NiOx as the Hole Transport Layer

Nickel oxide (NiO x ) has exhibited great potential as a hole transport layer (HTL) for fabricating efficient and stable perovskite solar cells (PSCs). However, it has been greatly limited by its fabrication and manipulation process. In this work, a simple processing method on an ultrathin electrochemical mesoporous NiO x film manipulated by controllable ultraviolet/ozone (UVO) treatmentis employed; the duration of UVO treatment on the NiO x film significantly affects the photovoltaic properties of the PSCs. When the exposure duration increases, the wettability, electrical conductivity, nonstoichiometry, and valence band energy of the NiO x film are improved with varying degrees. Besides, the perovskite grain size, recombination resistance at the perovskite/NiO x interface, and build‐in potential of the device also increase, resulting in higher short‐circuit current density ( J SC ) and open‐circuit voltage ( V OC ). Combining these factors together, an optimal exposure time of UVO treatment on the NiO x film has been achieved at 5 min, which results in a significantly high performance with an efficiency of 19.67%, large V OC (>1.1 V), and J SC (>23 mA cm −2 ). Furthermore, the experimental results are coincide well with simulation results on the different corresponding subjects. Hopefully, this work could facilitate material manipulation toward scalable, high efficiency, and stable solar cells.