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 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 (FAI). It is found that its product may control the intermediate precursor phase for regulated 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 PSCs deliver an efficiency of 25.19% and a high open-circuit voltage (V OC ) of 1.22 V. Additionally, the devices demonstrate good stability, with power conversion efficiencies (PCEs) remaining over 90% of their initial values under ambient atmosphere conditions for 60 days, high temperature of 85   °C for 200 h and maximum power point (MPP) tracking for 500 h. This article is protected by copyright. All rights reserved.