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1D-structure perovskite materials have gradually attracted people's attention due to the flexibility of their crystal structures and their strong stability to environments such as water and humidity. In this work, 1D/3D mixed-dimensional perovskite materials were achieved by adding large cation tBA+. The Cs+ doped high quality perovskite films (CstBAMAFA) were prepared by a two-step solution method, and the photoelectrical properties and stability of perovskite solar cells (PSCs) were systematically analyzed. The photoelectric conversion efficiency (PCE) of the champion Cs+ doped 1D/3D PSCs reached 17.08%, and the stability was significantly improved compared with the control group. The PCE of unencapsulated PSCs could retain 80% of the initial value after 197 days of storage in Ar glove box, and 69.3% of the initial value after 20 days of storage at 30 °C with a relative humidity of 50–60%. The improved efficiency and stability of Cs+ doped 1D/3D PSCs are attributed to the filling of the grain boundaries by the 1D phase. [Display omitted] • Larger tert-butylamine cation (tBA+) replaces MA+ to form a 1D/3D structure. • tBA+ regulates the size of the grain in the novel 1D/3D perovskite solar cell. • Multiple cations doped 1D/3D perovskites improve efficiency and stability. [ABSTRACT FROM AUTHOR]

Interfacial passivation of perovskite films is an effective way to further improve the power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). In this work, the combination of ionic liquid (IL) BMIMBF 4 and isopropanol (IPA) are used as green mixed anti-solvent. The existence of ionic liquids can delay the crystallization of perovskite and obtain dense perovskite films, because the non-volatile characteristics of BMIMBF 4 is left on the surface of perovskite, which is used for interfacial passivation. The perovskite film, which is prepared by mixed anti-solvent, can effectively reduce surface defects and significantly inhibit non-radiative recombination. Comparing with IPA as single anti-solvent, the PCE increased from 14.49% to 16.25%. In addition, the perovskite film with mixed anti-solvent still retains 76.8% of the initial efficiency after the unpacked PSCs are soaked in 100 mW/cm2 light for 20 days, and it retains 72.6% of the initial efficiency after 20 days of aging in an air atmosphere with 50∼60% relative humidity. The significant improvement of stability shows that the mixed green anti-solvent which combining BMIMBF 4 with IPA is an effective strategy for preparing stable PSCs by one-step method. [Display omitted] • Combining IL BMIMBF 4 with IPA are used as green mixed anti-solvent. • BMIMBF 4 left on the surface of perovskite is used for interfacial passivation. • Stability is significantly improved using the green mixed anti-solvent. [ABSTRACT FROM AUTHOR]