Intermediate-Controlled Synthesis of Quasi-2D (PEA)₂MA₄Pb₅I₁₆ in the 20–30% Relative Humidity Glovebox Environment for Fabricating Perovskite Solar Cells with 1 Month Durability in the Air

Herein, quasi-two-dimensional (Q-2D) (PEA)₂MA₄Pb₅I₁₆ (prepared by a two-step process) and hole transport layer of a solar cell were fabricated in a high relative humidity (25 ± 5%) environment. The PSC behavior of most Q-2D perovskites is worse than that of three-dimensional perovskites owing to the horizontal alignment of the innate characteristic organic plates on the substrate. Using hybrid immersion solvents (HISs), we have improved vertical alignment in an appropriate ratio to enhance the efficiency of charge transfer and the high coverage of the first priming layer (first step). The grazing incidence X-ray diffraction pattern of the optimized structures revealed a preferential orientation for the vertical alignment of (111), which improved the charge transfer in PSCs and micrometer-level grain size growth. The second step was processed in a high-humidity environment (50 ± 5%) (methylammonium iodide solution embedded), and Q-2D (PEA)₂MA₄Pb₅I₁₆ demonstrated distinct grain boundaries. The power conversion efficiency (PCE, 13.09%) of the champion device of the first priming layer prepared using the HIS system increased by >55% compared to the single-immersion solvent (8.3%). The PCE of the ion-modified ETL PSCs was 16.02% (CsF-3) and 14.58% (CsCl-3) and demonstrated 22 and 11% improvement, respectively. The ion-modified electron transport layer (ETL) was deposited in the air, which reduced the power consumption of preparing perovskite solar cells (PSCs). Finally, all Q-2D PSCs were stored in the air, and three PSCs (DMF/DMSO, CsF-3, and CsCl-3) using HIS exhibited long-term stability for 1 month maintaining 80-88% of PCE, demonstrating the importance of the HIS system to improve the first step of growth orientation, which enhances the stability and photovoltaic properties of PSCs.