Kind-I van der Waals heterostructures, wherein each the conduction and valence band edges of 1 materials lie throughout the bandgap of an adjoining layer, supply distinctive alternatives for engineering cost service confinement and enhancing gentle emission in two-dimensional programs. In our authentic work (M. Z. Bellus, M. Li, S. D. Lane, F. Ceballos, Q. Cui, X. C. Zeng and H. Zhao, Nanoscale Horiz., 2017, 2, 31–36, https://doi.org/10.1039/C6NH00144K), we demonstrated a type-I heterostructure fashioned by monolayer MoS2 and ReS2, verified by means of each first-principles calculations and time-resolved spectroscopy. Since then, rising curiosity in type-I band alignment has led to the invention of a broad vary of recent type-I programs by means of theoretical predictions and experimental strategies. Furthermore, dynamic tuning of band alignment through vertical electrical fields or pressure has enabled reversible transitions between type-II and type-I configurations. Purposes of type-I heterostructures in light-emitting and photodetection gadgets have additionally been experimentally explored. Trying forward, we anticipate continued improvement of type-I heterostructures with enhanced light-emitting efficiency and their integration into complicated multilayer stacks with combined band alignments to comprehend novel optoelectronic and quantum gadgets.