A “Guest-Solvent” Additive Strategy for Ambient-Printed Films with Enhanced Efficiency in FAPbI3 Perovskite Solar Cells and Modules†

Abstract

Achieving high-performance perovskite solar modules (pero-SMs) over large areas under ambient conditions remains a significant barrier to the commercialization of perovskite photovoltaics. This challenge arises from the strong solvent-perovskite coordination interactions in the hygroscopic perovskite precursor ink, which complicate the control of nucleation-growth kinetics and phase evolution during film formation in the presence of moisture, thereby hindering the formation of high-quality perovskite films. In this work, a “guest-solvent” additive strategy was developed by incorporating N,N-dimethylthioformamide (DMT) into the perovskite precursor ink to effectively modulate the coordination between the solvent and perovskite. It is demonstrated that DMT, structurally similar to the “main-solvent” system (DMF and DMSO), possesses lower coordination ability with Pb²⁺ and forms non-covalent interactions with the primary solvents. These interactions weaken the solvent-perovskite coordination without sacrificing solubility, thereby stabilizing homogeneous nucleation and promoting direct crystallization from the sol-gel phase to α-FAPbI₃. As a result, the ambient-printed FAPbI₃ films exhibited high quality, with more compact grain stacking, smoother morphology, higher phase purity, and fewer defects. Consequently, the resulting perovskite solar cells (0.062 cm²) and pero-SMs (15.64 cm²) fabricated via blade coating under ambient conditions achieved remarkable power conversion efficiencies (PCEs) of 24.46% and 22.54%, respectively.