Since the solid‐state photophysical behaviours of π‐conjugated molecules are responsible for the intrinsic single‐molecular properties and the solid‐state molecular orientations, the solid‐state photophysical properties such as fluorescence wavelength of them often vary from the solution state. To develop rational and reliable strategies to predict the solid‐state photophysical properties of π‐conjugated molecules, this study focused on pyrene chronophers, and found that pyrenes bearing appropriate alkyl groups showed similar emission profiles in both the solution and solid states, in sharp contrast with the parent pyrene which exhibited an excimer emission in the solid state. More information can be found in the Full Paper by Takanori Iwasaki, Nobuaki Kambe et al. on page 14817.