Hydrophobic Fluorinated Conjugated Polymer as a Multifunctional Interlayer for High-Performance Perovskite Solar Cells

It is known that the perovskite/hole transport layer (HTL) interface is a great limit to achieving high-performance perovskite solar cells (PSCs). Aiming to solve this problem, we introduce a naphthalene diimide (NDI)-based conjugated polymer bearing 3,4-difluorothiophene (PTzNDI-2FT) at the perovskite/HTL interface. We find that the PTzNDI-2FT interlayer combines multifunctions to passivate surface defects on the perovskite film, improve charge transport at the perovskite/HTL interface, and prevent penetration of the moisture and organic ion volatilization in the perovskite film. The champion device exhibits a power conversion efficiency of 23.2% under standard AM 1.5 G one sun illumination and offers excellent environmental, heat, and light stabilities.