Efficient micrometer-scale thick-film perovskite solar cells with superior stability

It is essential to enhance the thickness of the absorber layer for perovskite solar cells (PSCs) to improve device performance and reduce industry refinement. However, thick perovskite films (> 1 μm) are difficult to be fabricated by employing traditional solvents, such as N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO). Besides, it is a challenge to fabricate thick-film perovskite owing to the deteriorated surface morphology and serious defect density. Herein, a simple method was reported to deposit uniform pinhole-free perovskite films with a thickness of more than 2 μm utilizing the methylamine acetate (MAAc) ionic liquid as the solvent. Combined with methylammonium chloride (MACl) as an additive, thick-film perovskite with ~ 2 μm in grain size and few grain boundaries (GBs) was prepared, which dramatically improved the perovskite crystal quality and enhanced carrier transport performance. The final PSCs exhibited a power conversion efficiency (PCE) of 20.16%. The device showed improved stability with 95% of its initial efficiency in a nitrogen environment over 5000 h. This work provides an alternative strategy to produce extremely efficient and stable thick-film PSCs. It can be believed that this device has great potential in the application of large areas and laminated PSCs. Graphical abstract: (Figure presented.)