In Situ Synthesized Low-Dimensional Perovskite for >25% Efficiency Stable MA-Free Perovskite Solar Cells

Developing an additive to effectively regulate the perovskite crystallization kinetics for the optimized optoelectronic properties of perovskite film plays a vital role in obtaining high efficiency and stable perovskite solar cells (PSCs). Herein, a new additive is designed and directly synthesized in perovskite precursor solution by utilizing an addition reaction between but-3-yn-1-amine hydrochloride (BAH) and formamidinium iodide. It is found that its product may control the intermediate precursor phase for regulating perovskite nucleation, leading to advantageous 2D perovskite to induce growth of perovskite along the preferred [001] orientation with not only released lattice strain but also strong interaction with perovskite to passivate its surface defects. By taking advantage of the above synergistic effects, the optimized PSC delivers an efficiency of 25.19% and a high open-circuit voltage (VOC) of 1.22 V. Additionally, the devices demonstrate good stability, remaining over 90% of their initial efficiencies under ambient atmosphere conditions for 60 days, high temperature of 85 degrees C for 200 h, or maximum power point tracking for 500 h. An effective additive (BAH2) is in situ synthesized in perovskite precursor solution by a two-step addition reaction of but-3-yn-1-amine hydrochloride (BAH) toward formamidinium iodide (FAI) to regulate nucleation and growth of perovskite film along preferred orientation and release lattice strain by forming a low-dimensional perovskite. Consequently, the BAH-treated FACsPbI3 device achieves a remarkable efficiency of 25.19% and improved stability. image