Provided herein are all-inorganic perovskite-based films, devices including all-inorganic perovskite-based films, and methods of forming all-inorganic perovskite-based films. The methods may include casting a precursor formulation that includes an all-inorganic perovskite, a liquid, and a polymer. The amount of polymer in the precursor formulation may be less than the amount of all-inorganic perovskite in the precursor formulation.