Triple Interface Passivation Strategy Enabled Efficient and Stable Inverted Perovskite Solar Cells

In this work, we propose a triple passivation of the two in-between surfaces of the hole transport layer (HTL) and perovskite. The inorganic salt of potassium thiocyanate (KSCN) is introduced to simultaneously crosslink NiOx HTL and methylammonium lead iodide (MAPbI(3)), which can significantly improve both device performances and stability. In addition to potassium passivation, the thiocyanate shows two good passivation effects on perovskite and NiOx to achieve the triple passivation. The strong Ni-N bonding exhibits strong polar covalent bond properties to make the electron deviate from the Ni side. Meanwhile, the strong electrostatic force between S and Pb in MAPbI(3) makes the Pb atomic layer closer to perovskite to restrain the I atom. Meanwhile, the KSCN modification lead to better valence band alignment. Eventually, the KSCN meditated PSCs exhibit both high efficiency of 21.23% with open-circuit voltage of 1.14 V and 6-fold improvement of operational stability.