Improved quantum yield of thermally activated delayed fluorescence by nanoconfinement in organophilic octosilicate

A hybrid of a thermally activated delayed fluorescent dye (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene, designated as 4CzIPN) and an organophilic layered silicate (dioleyldimethylammonium-octosilicate) was synthesized to achieve high photoluminescence quantum yield (0.71) of the dye, which is the critical factor in device application. Absorption, photoexcitation, and luminescence spectra suggested that the molecular conformation of 4CzIPN in the organophilic silicate enabled the utilization of the S ₀ → S ₁ transition efficiently. Furthermore, thanks to the flexible assembly of the dioleyldimethylammonium moieties, 4CzIPN was dispersed in the hybrid to suppress concentration quenching. Emission spectra and photoluminescence lifetimes in ambient and N ₂ atmosphere revealed that the photoluminescence quantum yield increased by the utilization of transition to a lower vibrational state and protection of a triplet state of 4CzIPN from oxygen in air in the organophilic silicate.