Magnetron sputtered nickel oxide with suppressed interfacial defect states for efficient inverted perovskite solar cells

Abstract

Widely used spin-coated nickle oxide (NiOx) based perovskite solar cells often suffer from severe interfacial reactions between the NiOx and adjacent perovskite layers due to surface defect states, which inherently impair device performance in a long-term view, even with surface molecule passivation. In this study, we developed high-quality magnetron-sputtered NiOx thin films through detailed process optimization, and compared systematically sputtered and spin-coated NiOx thin film surfaces from materials to devices. These sputtered NiOx films exhibit improved crystallinity, smoother surfaces, and significantly reduced Ni3+ or Ni vacancies compared to their spin-coated counterparts. Consequently, the interface between the perovskite and sputtered NiOx film shows a substantially reduced density of defect states. Perovskite solar cells (PSCs) fabricated with our optimally sputtered NiOx films achieved a high power conversion efficiency (PCE) of up to 19.93% and demonstrated enhanced stability, maintaining 86.2% efficiency during 500 h of maximum power point tracking under one standard sun illumination. Moreover, with the surface modification using (4-(2,7-dibromo-9,9-dimethylacridin-10(9H)-yl)butyl)phosphonic acid (DMAcPA), the device PCE was further promoted to 23.07%, which is the highest value reported for sputtered NiOx based PSCs so far.