Blade-coated Large-area Perovskite Films And Their Based Solar Cells

Solar energy as a green renewable energy has gradually become one of the most promising energy sources.At present,metal halide perovskite solar cells?PSCs?,as the most rapidly developing third-generation photovoltaic technology,have received extensive attention in the scientific and industrial communities.To date,the power conversion efficiency?PCE?of small-area perovskite device has exceeded 25%,which is comparable to the commercial silicon solar cells.However,most certified or reported high-efficiency perovskite device preparation methods have greater limitations,resulting in smaller active areas of devices.And with the expansion of the active area,the efficiency of device decreased significantly,which restricts the perovskite industrialization of photovoltaic devices.The fabrication,performance and stability of large area devices over the order of square centimeters are in urgent need of further study.This paper mainly aims at the current large-area fabrication and stability of perovskite devices,using industrial compatible blade-coating method to prepare high-quality perovskite films.Using strategies such as process optimization,crystallization control,and defect passivation,the quality of crystallization of perovskite film is significantly improved,and the perovskite device with excellent photovoltaic performance is obtained,which is of great significance for the low-cost and scalable fabrication of the state-of-the-art perovskite devices.The main research contents and results are as follows:1.Optimization of the blade-coating process for perovskite film and preparation of large-area perovskite device.First of all,we independently designed and built a blade-coating platform.Moreover,the influence of substrate temperature,solution concentration and other factors on the prepared film was discussed during the blade-coating process.At the same time,the performance analysis and comparison of devices with different hole transport layers were carried out.The inorganic transport layer NiO_x significantly improved the open-circuit voltage and fill factor of the device.As a consequence,a large-area perovskite film and device with active area of 1 cm² was successfully obtained by blade-coating.The best device achieved 8.8%power conversion efficiency.This provides a reference for the subsequent scalable and high-quality preparation of perovskite films,and is also of great significance for the development of perovskite photovoltaic devices suitable for modular production.2.The properties of MAPb I₃ perovskite films and devices prepared by blade-coating were improved using surfactant assisted growth technology.We introduced surfactant PAA into the perovskite precursor solution to control the nucleation and crystallization process of the blade-coated film.The presence of PAA significantly improves the fluid drying kinetics during the crystallization process of the thin film,reducing the Bénard-Marangoni convection caused by the substrate temperature being too high,and making the connection between the crystal domains tighter.Thus,the uniform and highly crystalline MAPb I₃ perovskite films were obtained.At the same time,the mechanism of PAA in the process of blade-coating and its influence on the photoelectric properties of perovskite thin films were deeply discussed.Finally,the inverted planar perovskite solar cells fabricated based on this film achieved a power conversion efficiency of 14.9%,and the efficiency of a large-area device?1 cm²?also reached10.9%.Moreover,the repeatability and stability of the device have also been greatly improved.3.Zwitterion-stabilizing scalable bladed MA-free??phase Cs_0.1FA_0.9PbI₃ films.In order to further realize the preparation of methylamine-free perovskite films and devices with excellent thermal stability,the introduction of zwitterion in the formamidine?FA?-based perovskite realizes the synergistic effect of crystallization modulation and defect passivation.On the one hand,zwitterions can interact with the perovskite precursor solution to increase the Gibbs free energy during the film crystallization process,thereby delaying the film growth during the blade-coating process and stabilizing the FA-based perovskite in the??phase.On the other hand,the positive and negative charges of zwitterions can effectively passivate the charged ion defects in the perovskite film,improve the fluorescence lifetime of photogenerated carriers,and reduce the non-radiative recombination rate induced by the defects within the film.Finnally,high-quality large-area?-Cs_0.1FA_0.9PbI₃ perovskite films were obtained.Based on this film,the perovskite solar cell was successfully fabricated.Compared with the control device,the open-circuit voltage of PPS-doped device was significantly improved,and the efficiency was increased from 16.2%to 18.9%.Additionally,the films and devices exhibit excellent environmental stability and thermal stability.