Organic fluorine-based trifluoroethyl methacrylate as effective defect passivators enabling high-efficiency and stable perovskite solar cells

As a revolutionary photovoltaic technology, organic-inorganic perovskite solar cells (PSCs) have attracted increasing interests because of rapidly boosted power conversion efficiencies (PCEs) in the last decade. Nevertheless, the typical methylammonium lead iodide (MAPbI₃) perovskite suffers from the inferior perovskite film quality and high defect amount, retarding the stability and PCEs. Using additives as defect passivators to effectively decrease the defect density and improve the perovskite film quality is a facile and useful method to enhance the PCEs and stability of MAPbI₃-based PSCs. In this work, a new organic fluorine-based trifluoroethyl methacrylate (TFMA) is introduced into the perovskite precursor to effectively suppress the defect amount, enhance the perovskite film quality (larger grain sizes and fewer grain boundaries), adjust the energy level alignment, reduce the charge recombination and promote the electron extraction at the same time. By optimizing the amount of TFMA additive, the modified MAPbI₃-based cell delivers a superior PCE of 21.0%, which is 16% higher than that of the control device (18.1%). Moreover, the addition of TFMA also significantly improves the moisture and thermal stability of MAPbI₃-based PSCs. This work provides a simple and useful strategy for reducing defects and boosting the performance of organic-inorganic PSCs, which can facilitate the commercialization of PSCs.