PEPy-COF, a new covalent organic framework (COF), exhibits a shiny blue fluorescence under UV and visible light. In article number 2300412, Amin Zadehnazari, Alireza Abbaspourrad, and colleagues built PEPy-COF via a one-pot condensation reaction using perylene and pyrene building blocks. PEPy-COF features temperature-dependent and solvent-independent fluorescence and a semiconductor band gap making it an excellent candidate for temperature sensing devices.