Effects Of Additives On The Performance Of Methylamine-type Two-dimensional DJ Perovskite Solar Cells

In the research of perovskite solar cells,the performance of perovskite solar cells is mainly affected by thin film morphology control and interface engineering.Looking back on the past research on perovskite solar cells,additive engineering is the most commonly used method for the morphology treatment of perovskite solar cells.Therefore,the main method of this experiment is to control the morphology of the film through additives to obtain large and dense grains.When selecting the device structure,most perovskite device structures follow the dye-sensitized perovskite solar cell and adopt the positive structure.The disadvantage of mesoporous Ti O₂ is that it generally needs to be sintered at a high temperature above 400°C,which is not conducive to large-scale processing.and the development of flexible perovskite solar cells4 so we chose the flip-chip perovskite structure as the basis for the device structure.(1)We verified the efficient and stable quasi-2D perovskite prepared by synergistic effect of methyl ammonium chloride(MACl)and thiourea(TU)as additives.Cl^-in MACl can passivate the electron traps at the interface of PEDOT:PSS/perovskite active layer,and MACl can effectively assist crystal growth to induce crystal vertical orientation^[1],and effectively improve fill factor(FF)and open circuit voltage(V_oc).It can be seen from the SEM that MACl can make the surface of the perovskite film compact and smooth through delayed crystallization^[2].TU contains two amino groups and one S donor.The amino group can form a hydrogen bond with the I atom in the perovskite.At the same time,the S donor can form a Lewis acid-base adduct with the Pb atom,and can also form a Lewis acid-base adduct with the perovskite crystal.The amino groups form hydrogen bonds.Some studies have verified that TU can improve the performance of perovskite solar cells,and the results show that TU retards the crystallization process by forming Lewis acid-base adducts^[3]or by improving the connection at the interface of HTL and PVSK^[4].To this end,we synergistically acted two additives in the perovskite precursor solution to enlarge the perovskite crystal size and increase the crystallinity through delayed crystallization,and assist the vertical growth of perovskite crystals to promote charge transport.Through various characterizations,it is proved that the performance parameters of the perovskite thin film devices treated with TU+MACl double additives are better than those of the perovskite thin film devices treated with TU/MACl single additive.The results show that we have prepared the most excellent perovskite solar device through the synergistic method of TU+MACl dual additives,with an efficiency of12.16%.After 22 days of storage at 70%humidity,it still maintains 80%efficiency.(2)In this chapter,thiosemicarbazide(TSC)is used as a Lewis-based additive for research,and TU is used as a comparison reference for lateral comparison experiments.The S donor in TSC can coordinate with Pb I₂ as well as the S donor in TU.We verified that the non-radiative recombination and defects inside the perovskite system can be reduced by replacing TU with TSC as an additive,while increasing the crystallinity of the perovskite and improving the moisture resistance stability of the perovskite film.The PL test results show that TSC can improve the crystallinity of the perovskite at the top and improve the transport of charges at the interface compared with TU.XRD shows that the TSC-treated film has typical diffraction peaks of perovskite phase,and the peak intensity is much larger than that of the TU-treated perovskite film,indicating that the TSC-treated perovskite film has higher crystallinity and better orientation.Facilitate better charge transfer.After 16 days of storage in an atmospheric environment with a humidity of 40%,the TSC-treated thin-film devices did not undergo significant degradation,while the TU-treated thin-film devices underwent an obvious phase transition from reddish-brown to yellow,indicating that TSC can enhance the moisture resistance of the device than TU.At the same time,through the contact angle test,it was found that the contact angle of the TSC-treated perovskite film was twice that of the TU-treated perovskite film,which also verifies that TSC can improve the moisture resistance stability of the device.