Homogeneous Printing And Defect Regulation Of Large-area Perovskite Solar Cells

Owing to high absorption coefficient,long carrier diffusion length and tunable band gap,organo-metal halide perovskite solar cells（PSCs）are outstanding in the photovoltaic field.After just over a decade of development it has achieved a rapid breakthrough in power conversion efficiency（PCE）from 3.8%to 25.8%,which is already comparable to traditional silicon-based solar cells and can basically meet the requirements of commercialization.Large area preparation is a must for the commercialization of PSCs,while printing is a key means to achieve large area preparation.Although the recording efficiency of large area PSCs has been updated continuously in recent years,the PCE of perovskite devices decreases significantly with the increasing of printing area.The research shows that the main reasons for the decrease of efficiency are the inhomogeneous,non-dense and the increase of defects for the perovskite film as the processing size increases in the printing process.In this paper,by focusing on the mechanism of coffee-ring effect in the process of perovskite film printing as well as the formation and repair principle of crystal film defects the problems of poor homogeneity,undensity and many defects of large area perovskite films are investigated.Through the design of superwetting bionic interface（Bio-IL）and the construction of a large area of perovskite film defects rapid detection and in-situ repair system,combined with large area of perovskite module printing technology to achieve high efficiency,high stability and high reproducibility of large area of perovskite modules are printed.Specific research contents are as follows:1.By investigating the formation mechanism of the coffee-ring effect,and addressing the problems of poor homogeneity and pinholes,the biomaterial Levodopa was introduced to build a superwetting Bio-IL,which successfully suppressed the coffee-ring effect by regulating the spreading performance of the perovskite precursor ink on the substrate and the transport behavior of perovskite colloidal particles.Secondly,the interface design modulates the crystallization kinetics of the perovskite precursor ink and enables the preparation of large-area flexible perovskite films with homogeneous,dense and high crystalline quality.Therefore,the density of defect states of the perovskite films was reduced from 1.3×10¹⁶ cm^-3 to 1.13×10¹⁶ cm^-3.2.Based on the super-wetting Bio-IL design in the first chapter,combined with module printing technology,a large-area flexible perovskite film of 100 cm² was further printed.On this basis,a single perovskite solar cell（effective area of 0.1 cm²and 1.01 cm²）and a flexible large area perovskite module（effective area of 14.63 cm²）are assembled,and the PCE of 21.08%,18.16%and 16.87%are obtained,respectively.At the same time,the evolution law of device efficiency with the increase of effective area is studied,and it is proved that high quality and homogeneous perovskite film has a significant impact on the performance loss of perovskite devices and the performance of flexible modules.Meanwhile,it is also proved that the above-mentioned superwetting Bio-IL design plays a prominent role in the preparation of large-area flexible perovskite modules.3.To address the current problem of many defects and insufficient detection methods for large-area perovskite films,we have developed a method to detect defects in large-area perovskite films using Urbach’s energy value as a measure,and to evaluate large-area perovskite films by zonal detection.Finally,the areas to be repaired were liquefied using NH₃ at low temperatures in a targeted manner and recrystallized using a laser for rapid heat treatment.Based on this,a single small-area perovskite solar cell with an effective area of 1.01 cm² and a perovskite module with area of 25 cm² were printed and achieved PCE of up to 21.69%and 15.83%respectively.In addition,the efficiency of the defect-repaired perovskite devices was approximately 85%of the initial value after 1200 hours of storage,and the efficiency of the modules remained above 90%of the initial value after 400 hours of continuous operation.