LAUSR

Abstract This review mainly focuses on the topics related to metal complex based delayed fluorescence (DF) materials including their molecular design principle, photophysical studies, as well as their performance in the device settings. Due to the choice of various metal ions and metal complex system, metal based DF materials can be categorized into four major material classes based on their emission mechanisms at room temperature: (I) TADF materials exhibiting both fluorescence and DF; (II) TADF materials exhibiting DF only; (III) metal assisted delayed fluorescence (MADF) materials exhibiting both phosphorescence and DF; (IV) DF materials exhibiting fluorescence, phosphorescence and DF.