Perovskite solution, perovskite thin film, perovskite solar cell and preparation method

The invention relates to a perovskite solution, a perovskite thin film, a perovskite battery and a preparation method. The perovskite solution comprises a perovskite precursor and a cationic active agent, the cationic active agent comprises ethyl triphenyl phosphorus iodide and/or an ethyl triphenyl phosphorus iodide derivative. According to the invention, the cationic active agent is used in the perovskite solution, and the phenyl chain of the cationic active agent is connected with the perovskite to delay the crystallization of the perovskite, so that the perovskite crystal grains are enlarged, the roughness of the surface of the film is effectively reduced, and the film is smoother, thereby improving the liquid accumulation and stripe phenomena of the film; and moreover, the contact between the perovskite crystal grains and the interface is more uniform and compact, the crystallinity is obviously improved, the contact between the perovskite and the electron transport layer is facilitated, and the extractio