Interface Engineering\nby Unsubstituted Pristine Nickel\nPhthalocyanine as Hole Transport Material for Efficient and Stable\nPerovskite Solar Cells

Lead halide perovskite solar cells (PSCs) have been rapidly\ndeveloped\nin the past decade. With the development of a PSC, interface engineering\nplays an increasingly important role in maximizing device performance\nand long-term stability. We report a simple and effective interface\nengineering method for achieving improvement of PSCs up to 20% by\nemploying unsubstituted pristine nickel phthalocyanine (NiPc). Thermal\nannealing of NiPc improves the interface between NiPc and perovskite\nbecause of the incorporation of NiPc molecules into the perovskite\ngrain boundaries, which creates improvements in hole extraction from\nthe perovskite absorber layer, as evidenced by time-resolved photoluminescence\nmeasurements. This significantly improves the charge transfer and\ncollection efficiency, which are closely related to the improvement\nof the interface between perovskite and NiPc.