Suppressing surface and interface recombination to afford efficient and stable inverted perovskite solar cells

The top surface of the perovskite layer and the interface with the electron transporting layer play a key role in influencing the performance and operational stability of inverted perovskite solar cells (PSCs). A deficient or ineffective surface passivation strategy at the perovskite/electron transport layer interface can significantly impact the efficiency and scalability of PSCs. This study introduces phenyl dimethylammonium iodide (PDMAI₂) as a passivation ligand that exhibits improved chemical and field-effect passivation at the perovskite/C₆₀ interface. It was found that PDMAI₂ not only passivates surface defects and suppresses recombination through robust coordination but also repels minority carriers and reduces contact-induced interface recombination. The approach leads to a twofold reduction in defect densities and photoluminescence quantum yield loss. This approach enabled high power conversion efficiencies (PCEs) of 25.3% for small-area (0.1 cm²) and 23.8% for large-area (1 cm²) inverted PSCs. Additionally, PDMAI₂ passivation enabled PSCs to demonstrate steady operation at 65 °C for >1200 hours in an ambient environment.