Study On Performance Of Mixed Additives In Perovskite Solar Cells

Up to today,the economic development of human society is largely based on the exploitation and utilization of traditional fossil energy.With the gradual reduction of fossil energy reserves and environmental problems in the process of exploitation and use of fossil energy,people focus on the clean and renewable energy field.Solar cells can directly convert the clean energy of solar energy into electricity,so it has important strategic significance.Organic and inorganic hybrid lead halogen perovskite solar cells have the advantages of low cost,simple preparation process and high energy conversion efficiency,which has become the research focus of experts and scholars at home and abroad in recent years.The morphology and crystal quality of perovskite films significantly affect their photoelectric properties,such as light absorption,carrier mobility,carrier diffusion length and life,and ultimately determine the energy conversion efficiency of devices.Therefore,the optimization of the morphology and crystallization quality of perovskite films has always been an important research topic.One-step spin coating method based on inverse solvent is one of the most commonly used deposition methods to prepare high-quality perovskite films.This method is simple to operate,but the morphology of the films obtained is difficult to control,which is prone to low coverage and uneven crystal size.In addition,there are a large number of charged defects at the perovskite grain boundary and the surface of the perovskite film processed by one-step spin coating method.These defects,as the recombination center of carriers,capture carriers and produce non-radiative recombination,resulting in serious energy loss.In view of these problems,this paper uses the method of adding mixed additives into the precursor to control the crystallization kinetics of perovskite film and the defect passivation,in order to improve the photovoltaic performance of the device.In the first part,1,2-dichlorobenzene（DCB）additive was introduced into the perovskite precursor solution The study shows that DCB can influence the evolution of coordination complex in solution,and then adjust the colloid particle size in perovskite precursor solution.The strong complexation between[Pb Ix]^2-x（x=0-6）and the solvent in the precursor was weakened after DCB was added,and the solubility of[Pb Ix]^2-x increased.Compared with the reference film without DCB,the film prepared by adding 6%volume fraction DCB had higher crystallinity,dense film,increased grain size,and uniform and smooth film surface.Steady state,transient fluorescence and space charge limiting current test results show that DCB modified thin film carrier non-radiative recombination is inhibited,and the carrier mobility is higher.The energy conversion efficiency of the dc B-modified perovskite solar cell reaches 19.67%,and the hysteresis effect of the device is reduced.In the second part,we double-doped perovskite thin films using 2-mercaptopyridine（2-MP）and DCB as mixed additives.As a kind of bidentate ligand,the sulfur atom of the sulfhydryl group and the nitrogen atom in the pyridine ring can coordinate with Pb²⁺as Lewis base functional group,so as to effectively passivate the Pb²⁺structural defect at the grain boundary.At the same time,the study showed that the positive effect of DCB on the crystal quality of the film was retained,which effectively increased the grain size of perovskite and improved the interface contact between the perovskite layer and the transport layer.The non-radiative recombination of the perovskite film modified with 2-MP-DCB hybrid additive is inhibited,the defect density is reduced,and the device open-circuit voltage,filling factor and short-circuit current density are increased.The maximum energy conversion efficiency is further increased to 20.4%.At the same time,the storage stability of the device in the unpackaged environment is significantly improved,and the device still retains more than 80%of the original efficiency after 600 hours.