Research On Crystallization Regulation And Stability Of High-Efficiency Blade-Coating Perovskite Solar Cells In Ambient

In recent years,perovskite solar cells have occupied an important position in the field of photovoltaic research due to their excellent photoelectric performance,such as low cost,and solution processing characteristics,which have attracted extensive and rigorous exploration by the scientific community in this field.How to achieve low-cost,efficient,and high-stability large-area perovskite photovoltaic devices is currently the focus of research attention.However,most of the highly efficient perovskite devices are currently prepared by spin-coating in glove box,which theoretically limits the preparation of large-area devices.Although various processes compatible with the preparation of larger area devices,such as blade coating and slot-die,have been developed and a series of progress has been made,the nucleation and crystallization process still lack effective control due to the involvement of more complex fluid dynamics processes,resulting in lower device efficiency compared to spin-coated devices.In addition,when perovskite devices are prepared in air,more defects are prone to exist in the grain boundaries and interfaces,and the induced ion migration and intrinsic sensitivity to water and oxygen make the stability of perovskite devices under actual operating conditions such as heating,electric field,and light illumination still not ideal.Given this,this paper takes the approach of using large-area processes to fabricate efficient and stable perovskite solar cells in ambient environment as a starting point.It conducts systematic research work on crystallization,grain boundaries,and interface control as strategies to improve the photoelectronic performance and stability of perovskite solar cells fabricated in ambient.Specific research content is divided into the following three parts:（1）Research on crystallization engineering of blade-coating perovskite solar cells in ambient.In Chapter 2,using the classic MAPbI₃ composition as an example,we controlled the nucleation and crystallization process of the precursor solution,and increased the nucleation density by increasing the solvent evaporation rate.We eliminated the Rayleigh-Bénard convection-induced high roughness domain structure by eliminating the temperature difference between the upper and lower surfaces of the solution.This allowed for the preparation of various thickness-adjustable,smooth and continuous perovskite films.Furthermore,for the FAPbI₃ composition with a more ideal bandgap,we achieved crystallization control in ambient preparation process by introducing MACl.This preparation method is easy to extend to the preparation of other functional layers and has good application prospects for achieving high-performance perovskite solar cells.We explored carbon-based electrode devices and copper-based electrode devices and achieved standard devices with efficiencies of17.75%based on FAPbI₃ composition,and 19.38%based on MA_0.7FA_0.3PbI₃composition with PTAA as the hole transport layer and Cu as electrode.This laid a solid foundation for further exploring the effects of grain boundaries and interface control on device performance and stability.（2）Enhancement of the performance and stability of air-processed FAPbI₃devices by incorporating hyperbranched phthalocyanine as a dopant.In Chapter 3,we synthesized hyperbranched phthalocyanine copper（HCu Pc）additive for solution processing,and the optimal concentration of HCu Pc doping increased the efficiency of air-processed pure FAPbI₃ inverted-structured devices to21.39%.Characterization studies revealed that twisted phthalocyanine units were anchored at the perovskite grain boundaries via supramolecular interactions,effectively passivating the grain boundary defects.Additionally,experimental and theoretical studies demonstrated that HCu Pc enhances the carrier extraction in perovskite films.Due to the in-situ encapsulation of perovskite molecules by HCu Pc,water-resisted ability in grain boundaries is significantly improved,enabling the expansion of the processing window and enhancing the phase stability of FAPbI₃films under high humidity.Further stability tests showed that the device could maintain less than 7%degradation after continuous operation for 600 hours in a glove box.Moreover,in air with relative humidity of 30-40%,the HCu Pc-modified pure FAPbI₃ device based on a copper electrode could also operate stably for 100 hours without degradation.（3）Constructing stable 1D interfaces by large steric hindrance and strongly anchored ligands to improve the interface stability of perovskite solar cells.In Chapter 4,by introducing three-dimensional organic amine cations on the surface of perovskite,the diffusion space hindrance is significantly increased.The experimental results show that it forms a 1D perovskite crystal with strong interface bonding on the surface of perovskite,which effectively passivates the surface defects and does not diffuse or decompose even at high temperatures.In addition,this dense interface layer can also prevent copper ions in the electrode from diffusing to the perovskite,as well as iodine ions from diffusing to the copper electrode.This strategy avoids the interface degradation of traditional ammonium salt interfaces under high temperature and operational conditions,ensuring long-term stable effective defect passivation under high temperature operational conditions.Ultimately,not only did the device efficiency increase significantly from 20.81%to 23.30%,but it also demonstrated excellent high temperature and operational stability.After 1200 hours of maximum power point tracking at 55±5°C,it still retained about 95%of its initial efficiency.