Our partners at Nanchang University led by Prof. Kai Yao have developed a new coating of organic molecules that significantly enhances the efficiency of monolithic tandem solar cells made of silicon and perovskite while reducing costs. This breakthrough involves a surface passivation strategy that smooths out defects in the perovskite layer, specifically when applied to cheaper, microtextured silicon wafers produced by the Czochralski process. The coating, a fluorinated thiophenethylammonium compound (CF3-TEA), is applied using dynamic spray coating, resulting in a uniform layer that improves light absorption and electron transfer. This innovation allows the tandem cells to achieve nearly 31% efficiency and maintain long-term stability, creating a breakthrough for more efficient and cost-effective solar panels.