A mesoporous-planar hybrid architecture of methylammonium lead iodide perovskite based solar cells

We report a hybrid mesoporous-planar architecture of methylammonium lead iodide perovskite based solar cells, to combine the benefits of both the mesoporous and planar architectures in a single device. A mesoporous-TiO₂ grid was fabricated on a compact TiO₂ layer, through a self-assembly process based on directional wetting, providing regions with and without mesoporous-TiO₂, followed by perovskite deposition and back contact evaporation (hybrid cells). The hybrid cells showed up to 10.7% power conversion efficiency (PCE) as compared to 13.5% and 6.3% for their mesoporous and planar counterparts, respectively. Interestingly, the hybrid cells are found to show a short circuit current density (J_sc) as high as the J_sc of the mesoporous TiO₂ based cells and proved to conserve the current density even in the absence of mesoporous-TiO₂ from planar parts of the hybrid cells. The cells showed the best fill factor as compared to their mesoporous and planar counterparts. The areal variation in the meso to planar ratio has also been realized by changing the grid size to demonstrate the effect of the architecture on the cell performance. Charge extraction measurements have been used to obtain insight into the recombination inside different solar cells architectures. The hybrid cell structure emerged as a novel promising design for perovskite solar cells.