Boron Cluster Enhanced Ultralong Organic Phosphorescence.

Although carborane-based luminescent materials have been studied for years, no persistent phosphor has been reported so far. Herein, we describe boron-cluster-based persistent phosphors obtained by linking a sigma-aromatic carboranyl cage to the pi system of a carbazolyl group. The carboranes were found to promote intersystem crossing from a singlet to a triplet state. The rigid boron cluster was able to stabilize the ultralong triplet excitons through multiple non-classical hydrogen bonds, such as B-H center dot center dot center dot pi interactions, thus leading to a long lifetime of up to 0.666 s and an absolute phosphorescence quantum yield of 7.1%, which is outstanding for an organic phosphor without heavy atoms. These phosphors can be excited by visible light and show dynamic emission behavior, including thermochromism and mechano-chromism. This study demonstrates that non-metal/heavyatom boron clusters can be used to develop multifunctional high-performance phosphors for potential applications.