Performance Study Of Tin-Based Perovskite Solar Cells Based On Anti-Solvent Doping

As one of the rising stars of clean and renewable energy,perovskite solar cells have attracted much attention in the past few decades.The power conversion efficiency（PCE）of lead-based perovskite solar cells has increased from 3.8%to over 25%in just 10 years.In order to make perovskite solar cells more environmentally friendly,lead-free metals such as tin have been studied to replace lead as light-absorbing materials.FASnI₃ perovskite has a suitable optical bandgap,low exciton binding energy,and high carrier mobility,making it a very promising candidate for photovoltaics.However,compared with lead-based devices,the performance of current FASnI₃-based perovskite devices is not satisfactory.Due to self-doping,it is easily oxidized to Sn⁴⁺.In addition,the crystallization process of FASnI₃ perovskite film is too fast,which easily leads to too small grain size and causes many defects in the film.As a kind of interface engineering,anti-solvent engineering improves the device performance by introducing additives into the anti-solvent to modify the surface of perovskite.Based on this,this paper starts from the anti-solvent engineering and introduces suitable additives into the anti-solvent to improve the photoelectric conversion efficiency of tin-based perovskite solar cells.The specific experiment content is as follows:（1）Doping poly-9-vinylcarbazole（PVK）in the anti-solvent chlorobenzene,improve film quality,reduce carrier recombination,and improve device performance by passivating defects.Depositing a polymer layer in situ on the surface of the FASnI₃ film,the PVK polymer layer can not only promote the growth of FASnI₃ perovskite grains growth,reduce defects,and facilitate carrier transport.With the optimal concentration of PVK（5 mg/m L）,the PCE of the device improved to 6.81%,the Voc was0.48 V,the Jsc was 22.68 m A/cm²,and the FF was 62.03%.In addition,the improved devices also exhibited improved stability.（2）Doping acetaldehyde oxime（AO）in the anti-solvent chlorobenzene,improve photoelectric conversion efficiency and stability by inhibiting oxidation,increasing grain size,and improving film crystallinity.The oxime group（=NOH）in AO can act as a reducing agent,effectively neutralize oxygen molecules to inhibit oxidation,and interact with Sn²⁺to inhibit the formation of defects,this results in a low film defect density.The PCE of FASnI₃ devices with the optimal concentration of AO（5%）increased from 5.10%to 7.65%and the hysteresis effect was significantly weakened.The VB of the improved perovskite film was increased from-6.11 e V to-5.92 e V by UPS measurement,indicating that the energy level between the film and the PEDOT:PSS hole transport layer is more matched.In addition,after 1200 hours of continuous testing in a nitrogen-filled glove box,the PCE of the improved device is still 80%,showing excellent stability.（3）Doping tetraethyl silicate（TEOS）in the anti-solvent chlorobenzene improves the stability of the ammonium salt and improves the device performance by anchoring the ammonium salt in the perovskite solution.The ether bond in TEOS can anchor the ammonium salt in the perovskite solution,inhibit the subsequent ammonium salt from leaving the perovskite lattice,and coordinate with Sn²⁺,effectively improving the quality of the FASnI₃ film,thereby improving the performance of the device.At the optimal concentration of TEOS（5%）treatment,crystallinity increased and UV absorption enhanced,Defects are reduced and carrier recombination is suppressed.The Voc,Jsc and FF parameters of the best performance device were increased to 0.46 V,22.72 m A/cm² and 60.25%,respectively,and the highest photoelectric conversion efficiency was 6.23%.