On page 2316, M. A. Alam, S. K. Kim, and co-workers describe a 2D layered semiconductor used to fabricate a mechanically flexible, high-mobility thin-film transistor based on large-area and highly crystalline MoSe2 films grown by chemical vapor deposition (CVD). It is thought that such high-mobility materials will be indispensable for various future applications, such as high-resolution displays and human-centric soft electronics.