Additives and interface engineering facilitate the fabrication of high-efficiency perovskite solar cells in ambient air-processed

Herein, additives and interface engineering are used to reduce the defects of perovskite solar cells (PSCs) prepared in ambient air and improve its performance. Specifically, urea is introduced into TiO₂ and the perovskite layer, respectively. Both the contact angle and roughness of the TiO₂ layer are found to be improved, which is helpful to enhance the quality of the subsequent perovskite layer. In addition, urea is added into the perovskite layer to delay the crystallization process of PbI₂ by forming the intermediate products. And the larger grain size and appropriate number of pores are obtained, which lower the crystallization potential energy barrier of the perovskite film during the second-step spin-coating. Interface engineering between the perovskite bottom layer and the TiO₂ top layer by PEABr is found that the quasi-2D perovskite is generated at the bottom of the perovskite, and the 2D perovskite could passivate the interface defects of the 3D perovskite. Finally, CsCl is further added to the perovskite, which improves the tolerance factor of the perovskite film. Ultimately, the optimal device exhibits a champion PCE of 18.41%, a nearly 30% improvement compared to the original device, which could facilitate commercialization in ambient air environment.