Intermediate phase materials have very weak intermolecular forces in one dimension, making them easily exfoliated to form ultrathin two-dimensional materials with extremely high uniformity in layer thickness. Conventional two-dimensional materials exhibit strong intermolecular forces between nanosheets, leading to aggregation and reformation into crystalline phases. In contrast, monolayer two-dimensional intermediate phase materials lack strong intermolecular forces, making them easy to produce on a large scale without aggregation, thus representing a class of ultrathin two-dimensional materials that can be mass-produced.