Benzofurodibenzofuran as a universal chemical platform of highly efficient sky-blue thermally activated delayed fluorescence emitters and hosts

A benzofuran based chemical platform, benzofurodibenzofuran, was designed and synthesized as a core structure to develop hosts for phosphorescent organic light-emitting diodes and thermally activated delayed fluorescence (TADF) emitters. The high triplet energy and rigid molecular structure of the benzofurodibenzofuran unit enabled the universal application of it as the building unit of the sky-blue hosts and emitters. The sky-blue TADF emitters built on the benzofurodibenzofuran platform showed high external quantum efficiency, narrow emission spectrum and blue-shifted emission color compared with the conventional phenyl based emitters. Moreover, the high triplet energy hosts obtained from benzofurodibenzofuran efficiently harvested the triplet excitons of the sky-blue phosphors and TADF emitters. Therefore, the benzofurodibenzofuran can work as the basic platform of designing host and emitters for high efficiency sky-blue organic light-emitting diodes.