The inorganic CsPbX3 perovskite has received a lot of attention due to its high carrier transport efficiency and high thermal stability. However, solution-processed CsPbX3 perovskite solar cells' PCE is still significantly lower than that of their hybrid counterparts. Their devices' functionality is hampered by two main factors: insufficient film thickness and unwanted phase transition. Here, we demonstrate that the well-known solubility limitation for Cs precursors may be circumvented for the production of high-quality CsPbX3 perovskite films of considerable film thickness by using a novel precursor pair consisting of cesium acetate (CsAc) and hydrogen lead trihalide (HPbX3) (500 nm). To further encourage reduced-dimensional perovskite production, we added a small quantity of phenylethylammonium iodide (PEAI) to the solution. The resulting quasi-2D perovskites greatly lowered the trap density in the film by inhibiting unwanted phase transition. Using this method, we reported a 12.4 percent PCE for reduced-dimensional a-CsPbI3 perovskite photovoltaics, which is the best to date and has significantly longer performance lifetime than previous methods.

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