Recent progress in morphology optimization in perovskite solar cell

Hybrid organic-inorganic halide perovskite based solar cell technology has passed through a phase of unprecedented growth in the efficiency scale from 3.8% to above 25% within a decade. This technology has drawn tremendous research interest because of facile solution processability, ease of large scale manufacturing and ultra-low cost production of perovskite based thin film solar cells. It has been observed that performances of perovskite-based solar cells are extremely dependent on the morphology and crystallinity of the perovskite layer. The high-quality perovskite films have made a significant impact on the fabrication of efficient and stable hybrid perovskite solar cells. It has also been observed that device lifetime depends on the perovskite morphology; devices with larger perovskite grains degrade slowly than those of the smaller ones. Various methods of perovskite growth such as sequential deposition, doctor blading, slot die coating and spray coating have been applied to achieve the most appropriate morphology necessary for highly efficient and stable solar cells. This review focuses on the recent progress in morphology optimizations by various processing condition such as annealing condition, additive effects, Lewis acid-base adduct approach, precursor solution aging and post-device ligand treatment emphasizing on grain sizes, film uniformity, defect passivation, ambient compatibility and device efficiency and stability. In this review, we also discussed recently developed bifacial stamping technique and deposition methods for large-area and roll-to-roll fabrication of highly efficient and stable perovskite solar cells.