Fullerene-Anchored Core-Shell ZnO Nanoparticles for Efficient and Stable Dual-Sensitized Perovskite Solar Cells

Among all the solutions to improve long-term stability of perovskite solar cells, p-i-n heterojunction with all-metal-oxide charge transporting layers show their attractive features. However, these devices require an efficient electron-transporting layer (ETL) fabricated on top of the perovskites in which the commonly used oxide nanocrystals are limited by their imperfect surface. Here, a novel surface-passivation strategy was adopted by anchoring ZnO nanoparticles with fullerene nano-shells (Fa-ZnO) to mitigate trap states and passivate surface hydroxyl groups. We evidence the Fa-ZnO can be easily processed on top of perovskite as a high-quality ETL that improves electron extraction efficiency and suppresses ion diffusion/moisture penetration. In addition, the presence of fullerene shells allows Fa-ZnO nanoparticles to penetrate into perovskite precursors before crystallization, resulting in n-type sensitized configuration. With mesoscopic NiOx as hole-collecting contact, the p-n dual sensitization configuration has enabled all-metal-oxide devices to achieve state-of-the-art efficiencies of 21.1% with greatly improved performance longevity.