Spontaneous Passivation of Perovskite Solar Cells by Titanium Tetrafluoride

The efficiency, stability, and scalability of perovskite devices still require further enhancement for real-world application. Defect passivation has been recognized as one prominent strategy that can simultaneously promote the optoelectronic performance and stability of perovskite devices. Here, we demonstrate an additive, titanium tetrafluoride (TiF4), which could spontaneously enrich at perovskite interfaces and passivate the nearby charge traps efficaciously. Consequently, a power conversion efficiency of 20.19% was attained on the basis of the passivated device with TiF4, about 22% enhancement over that of the control device without TiF4. Moreover, the moisture stability of PSCs with TiF4 was significantly enhanced.