Pow(d)ering up: FAPI perovskite nanopowders for air-processed blade coated perovskite solar modules

Abstract

Formamidinium lead iodide (FAPI) is the most prominent perovskite material utilized in the fabrication of single-junction perovskite solar cells. However, the cubic α-phase perovskite is difficult to retain in precursor solutions for extended periods due to thermodynamic instability, which promotes the formation of the yellow δ-phase. In this study, we demonstrate the fabrication of solar cells and modules from FAPI powders synthesised using a single-step method with a non-hazardous solvent and routine purity grade lead iodide. The pre-synthesised α-FAPI and CsFAPI powders demonstrated considerable potential for scalability and reproducibility. It was observed that similar efficiencies were achieved in small-area cells and mini-modules fabricated using an industrially adaptable blade coating process conducted in an open environment. The enhanced solution rheology and the meticulous control of stoichiometry result in an oriented and less strained crystal lattice, thereby demonstrating superior reproducibility and stability of the perovskite prepared from pre-synthesised powder in comparison to the one produced from high-purity precursor. The methodology developed offers a scalable and cost-effective approach to the production of high-performance and stable perovskite solar modules, with efficiencies reaching 18.5% on a 12.15 cm² active area module and a T95 above 1200 h in shelf life stability at 30% RH in a UV-filtered environment.