Solvent-Free Luminous Molecular Liquids

Solvent-free luminous molecular liquids (LMLs) are a new generation of soft matter which exhibit uncharged, nonvolatile, and fluidic nature and emit intense and homogeneous luminescence in the condensed state. They can be produced readily on the gram scale by modifying luminophores with bulky, flexible, and low-melting side chains. Their performance can be facilely enriched by blending them with commercially available functional substances. Therefore, since their active optoelectronic properties were perceived a decade ago, LMLs have been regarded as promising contributing components in the burgeoning field of flexible and wearable light-emitting devices. Recently, richer insights into LMLs have triggered various new applications. Additionally, unexpected phase behavior and photophysical properties have been discovered coincidentally. Therefore, the sensible and sophisticated molecular design principles of LMLs are still being augmented to guarantee predictable, steady, and consistent end-use performance. This review summarizes the latest developments in LMLs, including molecular design principles, regulation and enrichment of their photophysical properties, and their versatile applications. Additionally, a prediction of the perspectives of LMLs in the near future is presented at the end.