Tridentate Locking Strategy Enables Multi-Dimensional Synergy at Buried Interfaces for High Performance Perovskite Solar Cells

Perovskite solar cells (PSCs) are hindered in both efficiency and commercialization by complex interfacial issues between the tin oxide (SnO₂) electron transport layer (ETL) and the perovskite (PVK) layers. Key challenges include interfacial defects, energy level misalignment, and weak interfacial bonding, which lead to non-radiative recombination and open-circuit voltage (V_OC) loss. To overcome these limitations, we propose an innovative tridentate locking strategy that employs N,N-bis(2-hydroxyethy)-2-aminoethanesulfonic acid (EBS) as an intermediate layer to establish robust tridentate coupling between SnO₂ ETL and PVK layer. The dual hydroxyl groups (─OH) of EBS serve as bridging chelators, forming strong coordination bonds with oxygen vacancies in SnO₂ and the halide ion vacancies in the PVK layer, respectively. Meanwhile, the sulfonic acid group (SO₃⁻) acts as a reinforced driving chelator that passivates uncoordinated Pb²⁺ ions within the PVK. This tridentate locking architecture enables synchronous defect passivation, suppresses non-radiative recombination, enhances ETL conductivity, and optimizes interfacial energy alignment. It also promotes stress redistribution, facilitating the formation of high-quality PVK films. Consequently, the n-i-p structured PSCs achieve a champion power conversion efficiency (PCE) of 25.17%. Moreover, the unencapsulated devices retain 85.4% of initial PCE after 1500 h of maximum power point tracking.