Preparation Of Color-adjustable Perovskite Films And Their Use In High-efficiency Perovskite Solar Cells

Perovskite thin film solar cells have attracted wide attention, because of their low manufacturing cost, adjustable absorption band gap, wide sources of raw materials, structural diversity, and high efficiency. Perovskite material is a semiconductor material, which is doped with organics and inorganics. The band gap can be adjusted by the difference of organic part, the halogen part and the metal core part. The structure can be described as AMX3. A usually means the organic cation, M the metal cation, and X represents the halogen ion. Its main part is the MX64" ligand eight structure, which is formed by the metal cations and the halide ions. M, located on the eight surface area, is connected by vault and halogen to form a network-like structure. The preparation methods of perovskite thin film materials, whether they are the one step, two step, evaporation or gas assisted solution phase method, are not suitable for the industrial application because of their disadvantages. As at present the preparation methods of the perovskite thin film material are not suitable for the industrial application, this paper firstly puts forward a simple and efficient method to prepare the high quality perovskite films with controllable components and adjustable color. And they are applied to plane type perovskite solar cells with the structure of FTO/bl-TiO2/perovskite/Spiro-OMeTAD/Au. After then, the battery device performance is characterized, and the efficiency of them is 12.76%,6.84%,4.12% and 3.53% respectively. The innovative results of the subject are shown as follows:1. Based on the current preparation methods of perovskite thin films, such as one step, two step, evaporation or gas assisted solution phase method, we grope firstly puts forward the method of direct solid contact reaction (DCIP) in order to offset the insufficient of the industrial production and application. First we spin-coat the lead halide solution and heat the substrate to form the lead halide film; then the lead halide thin films directly contact and react with halogen methylamine solid powder, which is placed in the aluminum reactor at 150 degrees’heating. Because the solid reactants are in direct contact in the reaction process, the preparation time of perovskite is shortened. And because it has the advantages of gas assisted liquid phase method, the prepared perovskite thin films have smooth surface, good crystallization, uniform grain size and high coverage.2. For the preparation of a particular perovskite films with controllable components, the paper innovatively uses different proportions of lead halide to react with correspondingly different halogen methylamine. For example, in the preparation of MAPbBr2I perovskite thin films, the lead bromide and iodide lead, with the ratio of 1:1, are added into DMF solution, which is innovatively used to prepare PbBrI thin film and subsequently reacts with methylamine bromine, avoiding the problem that the Br of the bromide lead film is substituted with the excess iodine in the methylamine iodine. Finally through the EDS component analysis, the Br/I of the four kinds of perovskite thin films are basically same with the theoretical value.3. The influencing factors in the preparation process of the perovskite thin films using the direct solid contact reaction are investigated, such as the lead halide’s solution concentration, the speed and time spin-coating, the heating temperature and time of the lead, the temperature and time of the direct contact reaction, the rinse time and so on. And the gradient experiment analysis is done to get the optimal experimental parameters. Then the phase structure analysis, the component analysis, and the analysis of surface morphology of perovskite thin films are also done to prove that the prepared perovskite films are in accordance with the requirements of perovskite cell devices.4. The structure of plane type perovskite cell and the methods of preparing the other layers of the perovskite cell are introduced. And the analysis of optical and electrical properties of the perovskite layer is also carried out. Then the properties of the prepared perovskite solar cells are tested and analyzed. The efficiencies of the prepared perovskite solar cells are 12.76%,6.84%,4.12% and 3.53%. This is the research scheme that the first time we prepare the color tunable perovskite thin films using the method of direct solid contact (DCIP) and then prepare the high efficiency perovskite solar cells in the field of perovskite cell research by far.