A Chelating-Agent-Passivated Electron Transport Layer for Efficient Perovskite Solar Cells with Enhanced Reproducibility

Substandard printing quality of electron transport layers (ETLs) always leads to non-ideal nucleation crystallization and bottom interface contact of the perovskite, followed by the formation of poor-quality perovskite films with severe heterogeneity, which is the major source of non-radiative recombination loss and environmental sensitivity of perovskite solar cells (PVSCs). These often result in serious photovoltaic performance loss, significant instability, and negative fabrication reproducibility. Herein, sodium phytate is proposed as a chelating agent for passivating the tin oxide (SnO2) ETLs to enable the stabilization of SnO2 nanoparticles and facilitate the printing of pinhole-free films, thereby realizing the controlled nucleation crystallization in perovskite precursor. Thus, the printed PVSCs exhibit a champion power conversion efficiency up to 23.77% with negligible hysteresis effect. The unencapsulated devices demonstrate outstanding long-term stability, which maintains over 80% of their initial efficiency under exposure to atmospheric environment (50% relative humidity) for 1500 hours, and a consistent and centralized distribution of efficiencies across all seasons, indicating their good reproducibility in diverse climatic atmospheres. Herein, sodium phytate is introduced to stabilize the tin oxide (SnO2) dispersion due to its strong interaction with SnO2 nanocrystal, thus suppressing the formation of agglomerations and facilitating the homogeneous deposition of printable SnO2 electron transport layers for perovskite solar cells (PVSCs). These also ensure controlled nucleation crystallization in perovskite precursor, effectively improving the photovoltaic performance, stability and all-weather printing reproducibility of the final PVSCs.image