Disclosed herein are inventive methods of making thin films, inventive thin films, and inventive articles and systems comprising thin films. Certain embodiments are related to methods of making thin films in which reagents are arranged within a first phase and a second phase such that at least one reagent reacts to form a thin film proximate to the interface between the first phase and the second phase. Thin films (including two-dimensional materials) disclosed herein can have one or more of a variety of beneficial properties including large lateral dimension(s), lateral continuity, high mechanical strength, consistent spatial composition, and/or consistent thickness. In accordance with certain embodiments, thin films disclosed herein can be combined to form a variety of inventive multi-layer articles, including multi-layer articles comprising a combination of thin films having different compositions that interact with each other via van der Waals forces.