Dopant-additive synergism enhances perovskite solar modules.

Perovskite solar cells (PSCs) are among the most promising photovoltaic technologies due to their exceptional optoelectronic properties1,2. However, the lower efficiency, poor stability, and reproducibility issues of large-area PSCs compared to laboratory-scale PSCs are major drawbacks that hinder their commercialisation3. Here we report a synergistic dopant-additive combination strategy using methylammonium chloride (MACl) as the dopant and a Lewis-basic ionic-liquid additive, 1,3-bis(cyanomethyl)imidazolium chloride ([Bcmim]Cl). This strategy effectively inhibits the degradation of the perovskite precursor solution (PPS), suppresses the aggregation of MACl, and results in phase-homogeneous and stable perovskite films with high crystallinity and less defects. This approach enabled the fabrication of perovskite solar modules (PSMs) that achieved a certified efficiency of 23.30% and ultimately stabilised at 22.97% over a 27.22 cm2 aperture area, marking the highest certified PSM performance. Additionally, the PSMs displayed long-term operational stability, maintaining 94.66% of the initial efficiency after 1000 h under continuous one-sun illumination at room temperature. The interaction between [Bcmim]Cl and MACl was extensively studied to unravel the mechanism leading to an enhancement of device properties. Our approach holds significant promise for bridging the benchtop-to-rooftop gap and advancing the production and commercialisation of large-area perovskite photovoltaics.