Investigation Of Perovskite Solar Cells Based On Cis-9-Octadecenylamine Interface Passivation

Perovskite solar cells（PSCs）using organic-inorganic hybrid perovskite materials as the light-absorbing layer have been developed for more than ten years.The most widely studied MAPbI₃perovskite material has good commercial development potential,owing to its advantages like long carrier diffusion lengths and high absorption coefficients,low exciton binding energy,low temperature solution processing,direct band gap semiconductor,etc.However,the perovskite films prepared by the solution process are polycrystalline,and its grain boundaries,surface defects,and interface defects between the light absorption layer and the transmission layer restrict the performance and stability of PSCs.In addition,as a thin-film solar cell,PSCs have have shortcomings like reflection loss,insufficient light absorption capacity of the light-absorbing layer,and spectral mismatch.The solution of these problems is expected to promote the further development of PSC photovoltaic devices and break the theoretical limit of its photoelectric conversion efficiency.In this work,we took tin oxide-based and titanium oxide-based perovskite solar cells as the research object,adopted the method of introducing passivation layer or using localized surface plasmon resonance enhancement effect to improve the efficiency and stability of solar cells,and comprehensively improved the cell’s performance,the main work content was as follows:（1）We introduced a cis-9-Octadecenylamine passivation layer at the interface between the light-absorbing layer and HTL of the tin oxide-based plana n-i-p PSCs and used the amino group of the cis-9-Octadecenylamine to passivate the under-coordinated lead,iodide ions and the interface of HTL.Studies have found that the formed cis-9-Octadecenylamine passivation layer can significantly inhibit non-radiative recombination and promote the extraction of holes at the interface between perovskite and HTL.On the other hand,the hydrophobic long-chain hydrocarbons extending outward on the surface of the perovskite can effectively prevent the corrosion of PSCs by water vapor.Under the optimal cis-9-Octadecenylamine concentration,the open circuit voltage of the prepared PSCs device increased significantly,and the average photoelectric conversion efficiency（PCE）reached 19.54%,which was nearly 24%higher than the average PCE（15.78%）of the reference device,the open circuit voltage increased from 1.05V to 1.15 V,resulting the champion PCE of the passivation device reached 20.87%.The unencapsulated cell could maintain more than 80%of the initial efficiency after being placed for 6 days under the condition of 50%relative humidity.This study showed that the introduction of cis-9-Octadecenylamine passivation layer to modify the perovskite and perovskite-HTL interface can effectively improve the efficiency and stability of PSCs.（2）In the mesoporous titanium oxide PSCs,gold nanorods（AuNRs）were introduced on the mesoporous titanium oxide,and an extremely thin insulating coating was grown on the mesoporous titanium oxide through thermal hydrolysis of magnesium salt.The study found that due to the longitudinal surface plasmon resonance（LPRs）characteristics of gold nanorods,AuNRs embedded in the TiO₂ mesoporous layer of the device exhibitd significantly enhanced near-field and scattered fields,increasing the optical path of incident photons in the cell,and improved the utilization rate of sunlight.At the same time,the insulating MgO cover layer could reduce the carrier recombination in the solar cell,isolate the direct contact of AuNRs to the perovskite and help enhance the photovoltaic performance.Compared with the unmodified reference PSCs,with the synergy of AuNRs and MgO,the power conversion efficiency of the PSCs was increased from 14.7%to 17.4%,showing an increase of over 18.3%,and could significantly improve the external quantum efficiency（EQE）of the device for long wavelength（>600 nm）photons.The Finite-difference time-domain（FDTD）method was used to numerically simulate the longitudinal surface plasmon resonance（LPRs）characteristics of gold nanorods,and the physical characteristics of perovskite solar cells based on the composite structure of gold nanorods/magnesium oxide were studied.The enhanced mechanism of gold nanorod plasmon photovoltaic.The mechanism of gold nanorod plasmon photovoltaic enhancement was discussed.