Excimer of Perylene in a Xerogel Matrix Shows Both Solution- and Solid-Like Dynamics

Fluorescence quenching in solid-state applications using polyaromatic hydrocarbons (PAHs) in optoelectronics can be mitigated by embedding them in a xerogel matrix. This study demonstrates a cost-effective method to reduce perylene's aggregation-caused quenching (ACQ) by coassembling it with a low-molecular-weight gelator made from cholesteryl chloroformate and pentaerythritol. For the first time, the optical properties of perylene in a xerogel are explored through comparative studies of perylene in powder, solution, and xerogel at various concentrations using steady-state and time-resolved emission spectroscopy. Time-resolved area-normalized emission spectra (TRANES) show a single-step interconversion between monomers and excimers in both perylene powder and solution. Perylene powder exhibits aggregate-induced excimer emission peaking at 600 nm, while concentrated perylene solution displays dynamic excimer emission at 540 nm with a single isoemissive point at 523 nm. In the xerogel matrix, perylene shows emissions from both monomeric and excimer states. The exciton dynamics at different concentrations reveal emission at 570 nm, the Y-state, a partially relaxed excitonic state, which then relaxes into the excimer (E) state emitting at 595 nm. These behaviors suggest a promising way to tune optical properties for PAHs-based optoelectronic materials. A cholesteryl-based host matrix also shows potential for maintaining solid-state emission in organic optoelectronic applications.