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As a benchmark semiconducting polymer, poly(3-hexyl-thiophene) (P3HT) has been broadly used to construct a wide range of organic electronic devices such as photovoltaic cells, photodetectors, thermoelectrics, and transistors. In the...

It is crucial to finely optimize the properties of hole transport materials (HTMs) to improve the performance and stability of perovskite solar cells (PSCs). Herein, a new spiro‐based HTM (Spiro‐4TFETAD) is developed by replacement of partial methoxy groups in Spiro‐OMeTAD with trifluoroethoxy substituents. Spiro‐4TFETAD has lower highest occupied molecular orbital level, higher thermal stability (Tg = 140 °C), hole mobility (2.04 × 10−4 cm2 V−1 s−1), and better hydrophobicity with respect to Spiro‐OMeTAD. The PSCs using Spiro‐4TFETAD achieve a power conversion efficiency of 21.11% and excellent humidity resistance. It maintains an average 83% of their initial power conversion efficiency values even in high relative humidity of 60% without encapsulation and 82% of its initial performance after 100 h continuous illumination at the maximum power point. The superior performance underscores the promising potential of the trifluoroethoxyl molecular design in preparing new HTMs toward highly efficient and stable PSCs.

High density of defects at interface severely affects the performance of perovskite solar cells (PSCs). Herein, cobalt (II) hexafluoro-2,4-pentanedionat (CoFAc), a hinge-type fluorine-rich complex, is introduced onto the surface of formamidinium cesium lead iodide (FACsPbI 3 ) film to address the issues of perovskite/Spiro-OMeTAD interface. The existence of CoFAc passivates both organic cation and halide anion vacancies by establishing powerful hydrogen bonds with HC(NH 2 ) 2 + (FA + ) and strong ionic bonds with Pb 2+ in perovskite films. In addition, CoFAc serves as a connecting link to enhance interfacial hole-transport kinetics via interacting with Spiro-OMeTAD. Consequently, FACsPbI 3 PSCs with CoFAc modification display a champion power conversion efficiency (PCE) of 24.64% with a charming open-circuit voltage (V OC ) of 1.191 V, which is the record V OC among all the reported organic-inorganic hybrid PSCs with TiO 2 as electron transport layer. Furthermore, CoFAc-modified devices exhibit an outstanding long-term stability, which can maintain 95% of their initial PCEs after exposure to ambient atmosphere for 1500 h without any encapsulation.

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