Two Birds with One Stone: Defect Passivation and Energy Level Optimization Achieved by Using Ionic Liquid Additives for Printable Mesoscopic Perovskite Solar Cells with Efficiency beyond 16%

Printable mesoscopic perovskite solar cells (p-MPSCs) have received extensive attention from researchers and entrepreneurs worldwide because of their low cost, simple manufacturing process, and feasible fabricate in air. However, the wide application of p-MPSCs is limited by their relatively low power conversion efficiency (PCE). Herein, we propose a performance enhancement strategy for p-MPSCs by introducing 1-benzyl-3-methylimidazolium chloride (BZMIMCl) ionic liquid into a perovskite precursor. The BZMIMCl ionic liquid optimized the crystallization of perovskite films, modulated the energy band alignment of the perovskite, and improved carrier transport, thereby enhancing the overall photovoltaic parameters and stability of p-MPSCs. The champion PCE of the BZMIMCl-optimized device was 16.06%. Moreover, the unencapsulated p-MPSCs containing BZMIMCl maintained similar to 89.6% of its maximum value after being stored for 60 days in an atmospheric environment (25 +/- 5 degrees C @ 50 +/- 5% RH, in the dark). This work further promotes the application of ionic liquids in the development of efficient pMPSCs.

Automated summary

Printable mesoscopic perovskite solar cells (p-MPSCs) have attracted global attention due to their low cost and simple manufacturing process, but their application is limited by low power conversion efficiency (PCE). This study proposes a strategy to enhance PCE by introducing 1-benzyl-3-methylimidazolium chloride (BZMIMCl) ionic liquid into the perovskite precursor. The BZMIMCl ionic liquid improves the crystallization of perovskite films, modulates energy band alignment, and enhances carrier transport, resulting in improved photovoltaic parameters and stability. The optimized device achieved a champion PCE of 16.06% and maintained 89.6% of its maximum value after 60 days in an atmospheric environment.