Increasing V_OC of Inverted Inorganic Perovskite Solar Cells Through Nickel Oxide Modification

Abstract Compared to conventional structure inorganic perovskite solar cells (PSC), the power conversion efficiency (PCE) of inverted structure devices still falls behind. In inverted structures, the commonly used hole transport layer (HTL), nickel oxide (NiO_x), is hindered by low carrier transport efficiency. To address this issue, nickel oxide nanoparticles with potassium hexafluorosilicate (KSiF₆) in inverted CsPbI₃ perovskite solar cells are modified. The high electronegativity of KSiF₆ leads to an increased content of Ni³⁺ in NiO_x, greatly enhancing the electrical conductivity. Meanwhile, potassium (K) from the modified HTL diffuses into the perovskite layer after annealing, which further passivates defects at the grain boundaries. As a result, a PCE of 19.8% is achieved under ambient air conditions, with the open–circuit voltage (V_OC) significantly increasing from 1.14 to 1.21 V.