Luminescence in Crystalline Organic Materials: From Molecules to Molecular Solids

Abstract

Luminescent small, all‐organic molecules are of tremendous interest in materials and life science applications. Nevertheless, targeted design requires a basic understanding of the excited state deactivation pathways of the molecules themselves, and the modulations of the processes that occur in the solid state. This particularly concerns crystalline molecular solids, as here not only solid‐state rigidification contributes to these modulations, but specific intermolecular interactions as well. Starting from the molecular properties, this work carefully disentangles all intramolecular and intermolecular factors to the radiative and nonradiative processes in crystalline all‐organic molecular solids to provide guidelines for targeted molecular materials design.

Persistent room temperature phosphorescence films based on star-shaped organic emitters

“…32–35 Recently, significant progress has been made in crystal-based metal-free ultralong phosphors. 6,36–42 However, the poor reproducibility, processability, and flexibility of these crystal-based materials will greatly hinder their further development. 14,43–45 Especially, the preparation of their thin films is always a critical and challenging task, while thin films with desirable optical properties are highly desired for many important practical applications.…”

Recent Trends in the Design, Synthesis, Spectroscopic Behavior, and Applications of Benzazole-Based Molecules with Solid-State Luminescence Enhancement Properties

“…geometrical factors affecting the molecular planarity, polarizability issues, exciton coupling and excimer formation [13,14]) related to the molecular arrangement and to morphological features. A recent and very inspiring review from Gierschner et al [15] identifies these effects and shows how difficult it is to disentangle them. Reasons for fluorescence quenching in the solid state are therefore of high complexity.…”

Pure Boric Acid Does Not Show Room‐Temperature Phosphorescence (RTP)

“…Therefore, on the one hand, introducing heavy atoms to enhance the SOC and incorporating non‐metal heavy atoms or carbonyl groups with lone pairs [14] are useful approaches to develop RTP systems with high performance [15] . On the other hand, suppressing the nonradiative decay path through vibrational‐assisted relaxation and avoiding collisions with O 2 by crystallization or polymerization are also key to realizing persistent afterglow [5, 16] . A variety of organic RTP materials were developed by utilizing the above strategies.…”