Phosphorescence sensitization via heavy-atom effects in d(10) complexes

Heavy atom-induced phosphorescence of organic chromophores that originates from spin-orbit coupling (SOC) is always accompanied by fluorescence quenching concomitant with a reduction of the triplet excited state lifetime. However, such changes are typically manifest by fluorescence quenching at room temperature and phosphorescence sensitization at cryogenic temperatures. Herein we overview our efforts over the past decade in which both internal and external heavy-atom effects (HAEs) can trigger room temperature phosphorescence (RTP) with dramatic shortening of the phosphorescence radiative lifetime by several orders of magnitude. Such spectral properties render new classes of phosphorescent materials for potential use in organic light-emitting diodes (OLEDs). The molecular systems described in this paper are organic fluorophores that are pi-complexed or sigma-bonded to a multinuclear d(10) transition metal center, the presence of which leads to phosphorescence sensitization because of