Activating Organic Phosphorescence via Heavy Metal-π Interaction Induced Intersystem Crossing

Heavy-atom-containing clusters, nanocrystals, and other semiconductors can sensitize the triplet states of their surface-bonded chromophores, but the energy loss, such as nonradiative deactivation, often prevents the synergistic light emission in their solid-state coassemblies. Cocrystallization allows new combinations of molecules with complementary properties for achieving functionalities not available in single components. Here, the cocrystal formation that employs platinum(II) acetylacetonate (Pt(acac)(2)) as a triplet sensitizer and electron-deficient 1,4,5,8-naphthalene diimides (NDIs) as organic phosphors is reported. The hybrid cocrystals exhibit room-temperature phosphorescence confined in the low-lying, long-lived triplet state of NDIs with photoluminescence (PL) quantum yield (phi(PL)) exceeding 25% and a phosphorescence lifetime (tau(Ph)) of 156 mu s. This remarkable PL property benefits from the noncovalent electronic and spin-orbital coupling between the constituents.

Automated summary

This study reports the formation of a hybrid cocrystal using Pt(acac)2 and NDIs, which exhibits high photoluminescence quantum yield and long lifetime, benefiting from the noncovalent electronic and spin-orbital coupling between the constituents.