A simple one-step method with wide processing window for high-quality perovskite mini-module fabrication

The one-step antisolvent approach is a widely employed method for fabricating perovskite devices at a low cost. However, the current antisolvent approach requires a strict set of processing conditions to obtain high-quality perovskite layers. Here, we introduce sulfolane as an additive in the perovskite precursor to convert the perovskite phase via a new reaction route, providing a large degree of flexibility to process crystalline perovskite layers with high uniformity on a large scale. As it is revealed by X-ray diffraction and Fourier-transform infrared spectroscopy findings, we find that the key concept lies in intermolecular hydrogen-bonding forces’ interaction between sulfolane and methylammonium iodide, which slows down the nucleation and subsequently the crystallization process. As a result, we demonstrate a mini module, 36.6 cm² active area, and achieve a record PCE of 16.06%. More importantly, the encapsulated mini module retained about 90% of the initial performance after operating at the maximum power point under simulated AM1.5G irradiation for 250 h at 50°C.