Barrier‐Free Cathode Contacts for High‐Efficiency Inverted Carbon‐Perovskite Solar Cells

ABSTRACT Compared to vacuum‐deposited electrodes of metal or metal oxides, printable carbon electrodes (CEs) offer a more sustainable approach toward commercialization of perovskite solar cells (PSCs). Significant attention has been paid to the N‐i‐P carbon‐based PSCs (C‐PSCs), owing to the favorable alignment of CEs work‐functions with perovskite valence band. In contrast, the P‐i‐N structured PSCs employing carbon as electron‐collecting contact has been rarely explored, primarily due to the presence of large interfacial barrier. Here, we eliminate the stubborn interfacial barriers by means of increasing free carrier density of electron transport layer (ETL) in conjugation with the insertion of a non‐conducting metal thin layer between ETL and CEs. The synergistic strategies enable the preparation of efficient P‐i‐N C‐PSCs with a record efficiency of 22.79% (certified 21.34%). The detailed life cycle cost and assessment reveal that our P‐i‐N C‐PSCs outperform metal‐electrode counterparts in both cost‐effectiveness and environmental impact.