Triad of Passivation Strategies for the Fabrication of Perovskite Solar Cells with Mitigated Defects and Enhanced Efficiency

Abstract

In the rapidly evolving field of perovskite solar cells (PSCs), addressing defects poses a significant challenge due to their diverse nature and varying patterns based on location. Effective defect control is crucial for achieving high efficiency in PSCs. In this work, a synergistic triad of passivation strategy was proposed, termed the “three-in-one” approach. This method incorporates a multifunctional molecule, PTR, into the PbI₂ precursor solution during the two-step fabrication of perovskite film. The carboxyl group (─COOH) of PTR interacts with SnO₂ to rectify oxygen vacancies on its surface, alleviating residual stress at buried interfaces. Due to its large volume, PTR is confined to grain boundaries (GBs) and gradually diffuses towards upper/ buried interfaces. Functional groups such as carbonyl (C═O), sulfurcarbon (C═S), and carboxyl (COOH) play key roles in mitigating defects at GBs and both interfaces. Additionally, PTR acts as an interfacial bridging that connects electron and hole transport layers. Consequently, the power conversion efficiency (PCE) of the optimal device (n-i-p configuration) improved significantly from 23.04% (pristine) to 25.77%, with a certified value of 25.44%. The introduction of this triad passivation strategy effectively addresses defects at GBs and both interfaces, paving the way for enhanced performance in PSCs.