Research On High-performance Photoelectric Conversion Devices Prepared By Blade-coating

Photoelectric conversion converts light energy into electrical energy for use.Solar cells,as alternatives of fossil fuels,can significantly convert sunlight to electricity,achieving the efficient utilization of renewable energy and effectively reducing the environmental pollution.As an important unit in an intelligent optoelectronic system,photodetectors can convert optical signals into electrical signals,and have played an increasingly important role in many fields such as military national defense,infrared imaging,optical communication,marine exploration,environmental protection,basic scientific research,imaging and other fields.Perovskite have attracted great attention due to its unique properties of high carrier mobility,large absorption,flexibility,light weight and adjustable band gap.Most of the researches published so far are small-area perovskite devices prepared by spin-coating in the laboratory,and the size is usually less than 0.1 cm~2,which cannot meet the market demand for large-area imaging detection and the mass production of cells.There is no doubt that the future development of perovskite will inevitably move towards large-scale preparation,so the realization of large-scale preparation is one of the most urgent problems to be solved at present.In order to solve the problem of large-area preparation,among many methods,blade-coating method stands out owing to its low cost,simple operation and environmental protection.Based on the current developments of organic-inorganic hybrid perovskite,this paper introduces blade-coating method into the preparation process of perovskite thin films,and successfully realizes large-area,large-grained,and highly uniform perovskite thin films.The practical application value of large-area imaging detection is demonstrated.The specific work content can be roughly divided into the following two parts:For the first work,we selected FA_0.4MA_0.6Pb I₃ perovskite for research.First,we studied various factors affecting the preparation of high-quality thin films by blade-coating.After the successful exploration,we introduced it to achieve the large-scale preparation of perovskite,and obtained perovskite solar cells（PSCs）with high stability.The hydrophobic alkyl chains in the WZM passivation layer are attached to the surface of the perovskite film like a barrier,which effectively resists the intrusion of water.Compared with the pristine devices prepared by blade-coating method,the moisture stability of the devices is significantly improved,retaining more than 70%of the pristine PCE after 120 hours of storage.The open circuit voltage was increased from 0.99 V to 1.06V.Under the illumination of AM 1.5G,the overall PCE of the device increased by 2～3%,reaching16.8%.Reproducibility is significantly enhanced.FF also reached 74.65%.These fully demonstrate the applicability of blade-coating in the perovskite field,laying a solid foundation for the subsequent large-area detection and imaging.The second work,based on the research foundation of the first work,went on to complete a large-area detection imaging.In addition,the passivation effect of the bifunctional non-fullerene material WZM on the perovskite layer is also demonstrated.The grain size of the passivated film is significantly larger and more complete,the film is also denser,and the film thickness is also significantly increased.The EQE of the passivated device exceeds 80%,the dark current is as low as 1.07*10^-7 A cm^-2 at-0.1 V,and the specific detectivity is increased to 3.44*10¹¹ at 770 nm.Finally,we expanded the area of the substrate and active layer,with a size of 48 mm*39 mm,and continued to perform an 8×8 array preparation to achieve a large-area imaging of visible light.It is believed that the large-area imaging application prepared by blade-coating has great potential and can be applied to more photodetection fields.In this paper,the proposed principle is analyzed in detail,and complete performance tests and data are provided to prove it.Not only the large-area high-performance perovskite device is prepared by the introduction of the blade-coating method,but also the moisture stability of the device and large-area detection capabilities are greatly improved.These effectively solve some of the problems existing in the marketization of perovskites,and provide definite ideas for subsequent research.I believe that this has played a valuable role in the practical value of perovskites in people’s lives.