Host‐Matrix Interactions and Molecular Functionalization: Shaping the Delayed Emission Properties of Indenophenanthridine Derivatives

The advancement of organic room temperature phosphorescence (RTP) materials has attracted considerable interest owing to their extensive applications. Their distinct advantages, including a metal‐free composition, low toxicity, and facile synthesis under ambient conditions, make them highly desirable. This study examines the delayed fluorescence (DF) and RTP of metal‐free, amorphous indenophenanthridine (IND)‐based derivatives (1–10) and provides insights into molecular functionalisation and host matrix effects on delayed emission (RTP and DF). IND derivatives have been used in bioimaging and organic analyte detections; however, their delayed emission mechanism photophysical processes are poorly understood. This work examines the derivatives’ physicochemical properties and time‐resolved photophysics to determine how molecular structure, host interaction, and delayed emission properties relate. The described IND compounds show RTP and/or TTA (triplet‐triplet annihilation) delayed fluorescence depending on the host environment. This research lays the groundwork for designing and developing new materials with increased RTP efficiency for future applications by detailing the detailed RTP processes and the crucial function of the host matrix.