A novel electroplex host with dual triplet exciton up-converting channels suppressing triplet exciton induced degradation mechanisms in blue organic light-emitting diodes

A novel electroplex host with two triplet exciton up-converting channels for suppressed triplet exciton triggered degradation mechanisms was developed using an electron transport type host (n-type host) with thermally activated delayed fluorescence (TADF) characteristics to improve the device lifetime of deep blue phosphorescent organic light-emitting diodes (PhOLEDs). The TADF-natured n-type host with high triplet energy was derived from triazine with benzonitrile and carbazole units to induce the TADF characteristics. The TADF natured n-type host generated an electroplex with a hole transport type host and the electroplex-based PhOLEDs revealed an extended device lifetime by more than twice compared to the non-TADF natured n-type host based electroplex host. Transient photoluminescence and electroluminescence analyses revealed that two reverse intersystem crossing (RISC) mechanisms through the n-type TADF host and electroplex host could suppress triplet exciton related degradation and improved the device lifetime. Kinetic modeling of the electroplex supported the RISC mechanisms of the electroplex.

Automated summary

A novel electroplex host with two triplet exciton up-converting channels was developed to suppress triplet exciton triggered degradation mechanisms, improving the device lifetime of deep blue phosphorescent organic light-emitting diodes (PhOLEDs). The host, with thermally activated delayed fluorescence (TADF) characteristics, generated an electroplex with a hole transport type host, resulting in an extended device lifetime compared to non-TADF natured hosts. Two reverse intersystem crossing (RISC) mechanisms through the TADF host and electroplex host were identified to suppress triplet exciton related degradation and enhance device lifetime, supported by kinetic modeling of the electroplex.