Achieving Persistent, Efficient, and Robust Room-Temperature Phosphorescence from Pure Organics for Versatile Applications

Abstract

Pure organic persistent room-temperature phosphorescence (p-RTP) under ambient conditions is attractive but challenging due to the slow intersystem crossing process and susceptibility of triplet excitons. Fabrication of pure organic RTP luminogens with simultaneously high efficiency and ultralong lifetime still remains a daunting job, owing to their conflicting requirements for the T₁ nature of (n,π*) and (π,π*) characteristics, respectively. Herein, a group of amide-based derivatives with efficient p-RTP is developed through the incorporation of spin-orbital-coupling-promoting groups of carbonyl and aromatic π units, giving impressive p-RTP with lifetime and efficiency of up to 710.6 ms and 10.2%, respectively. Furthermore, two of the luminogens demonstrate intense p-RTP after vigorous mechanical stimulation, indicating their robust nature, which is rarely encountered. Efficient and robust p-RTP even in the amorphous state endows them promising potential for encryption and bioimaging with facile fabrication processes. A bioimaging study with live mice indicates that such highly robust p-RTP is tremendously beneficial for in vivo afterglow imaging with an ultrahigh signal-to-background ratio of 428. These results strongly imply the possibility of realizing efficient and robust p-RTP from pure organics even without meticulous protection, thus paving the way to their promising and versatile applications.

Keywords: bioimaging; mechanochromism; persistent room-temperature phosphorescence; pure organic luminogens.