Optimizing The Fabrication Process Of Inverted Planar Perovskite Solar Cell Devices

In recent years,the field of organic-inorganic hybrid perovskite solar cells is booming because of their high photoelectric conversion efficiency and low-cost preparation by solution processing.They have a variety of device structures,including traditional mesoporous structure and n-i-p type planar heterojunction structure as well as p-i-n type inverted structure.Inverted structure has many advantages,including its simple structure and liquid preparation process.Therefore,it has attracted huge attention of researchers around the world in the fields of flexible electronics,large-scale devices.At present,there are two main problems in inverted organic-inorganic hybrid perovskite solar cells:the first one is how to control the growth of perovskite polycrystalline thin films;the other is whether the energy levels of each layer of the device can achieve ideal matching.In this dissertation,we focus on developing effective strategies to control the crystallization process and morphology evolution of perovskite films in different aspects based on several basic performance parameters of photovoltaic devices and the premise of low-cost fabrication.These research works are summarized based on the following three chapters:?1?In order to improve the open-circuit voltage of basic devices,we chose inorganic hole transport materials with better matched band gap and energy level for inverted perovskite solar cells and optimized the preparation of hole transport layer.The main work includes selection and synthesis of hole transport materials,?preparation of NiO_x and CuO_x nanoparticles and dispersions?,fabrication of different hole transport layers,fabrication and characterization of inverted devices based on different transporting materials.Finally,the power conversion efficiency of the champion device is more than 15%.?2?We use one-step spin-coating with anti-solvent?toluene?method to find out the appropriate time and mechanism of anti-solvent dropping.Then we use lead acetate as lead source with one-step anti-solvent-free method to fabricate perovskite thin film.By comparing different processes,we further optimize the fabrication process of perovskite.Finally,using doped perovskite precursors with anti-solvent-free method,we achieved high-repeatability and high-efficiency devices.The power conversion efficiency of the champion device is over 17%.?3?The effects of additives on the morphology of perovskite layer under different mechanisms were investigated by comparing three different kinds of additives.The main work includes:grain boundary passivation with carbon quantum dots?PCE over 18%?,introduction of pure inorganic perovskite BiFeO₃ in anti-solvent?PCE over 15%?,large-grained perovskite polycrystalline thin films induced by inorganic salt NH₄SCN?grain size reached 2.7?m?.