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

Abstract

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.