Refining interface compatibility and carrier management via π-π conjugated stacking for efficient and stable perovskite solar cells based on low-temperature processing

Abstract

Deficiencies and instability in the ETL, perovskite layer, or their interface contribute to carrier nonradiative recombination losses. To address these issues, we propose an electron collection and injection optimisation strategy that focuses on enhancing the compatibility and charge transfer performance at the ETL-perovskite interface. Our approach involves low-temperature modification TiO₂ with pyrimidine-2-carboximidamide acetate (PCA) through π-π stacking, reducing the surface energy and improving the interfacial compatibility. At the same time, a stable organic–inorganic hybrid layer is formed with lead iodide (PbI₂) below the perovskite layer. Additionally, we demonstrate long-term ambient stability, with the PSCs retaining approximately 90% of their initial PCE after 100 days. We also fabricate large-area modules, achieving an efficiency of 19.53% with an active area of 36.41 cm².

Highlights

The introduction of the π-π stacking multifunctional molecule PCA through a low-temperature process to modify TiO₂ film enhances the stability and performance of perovskite solar cells. This novel approach improves interfacial compatibility and reduces defects at the interface, enabling vertically aligned crystal growth of perovskite and increasing the interfacial contact area. By effectively removing two types of Hydroxyl groups over the low-temperature TiO₂ film through multiple surface chemical reactions, the strategy mitigates nonradiative recombination, leading to reduced energy losses and improved performance in both small and large-area perovskite solar cell modules.