Creation of a thermally cross-linkable encapsulated TADF molecule for highly efficient solution-processed hybrid white OLEDs

Abstract

Robust luminogens that can be used in application for high efficiency solution-processed hybrid white organic light-emitting diodes (WOLEDs) are rarely reported. Herein, a thermally cross-linkable encapsulated thermally activated delayed fluorescence (TADF) molecule, DVCz-2CzCN, consisting of blue emissive core, encapsulation unit and thermal cross-linkable group is designed and synthesized. Systematic studies demonstrate that DVCz-2CzCN as the emitter can form a stable and uniform thin film by the solution-process, and simultaneously suppress the triplet excitons concentration quenching. Consequently, the nondoped blue solution-processed device using DVCz-2CzCN as the emissive layer exhibits blue emission with maximum external quantum efficiency (EQE) of 5.6% is achieved. Especially to solution-processed hybrid WOLED with the construction of employing the cross-linked DVCz-2CzCN as the blue-emitting component combined with an orange-emitting phosphor PO-01, exhibits a superior performance with maximum forward-viewing EQE of 14.9% and a stable Commission International de L'Eclairage (CIE) coordinate of (0.33, 0.45). This work indicates that molecular topology construction is crucial for the development of high-performance solution-processed hybrid WOLEDs. Herein, a highly efficient solution-processed hybrid white OLED was reported based on the strategy of constructing a thermally cross-linkable encapsulated TADF molecule. • Solution-processed hybrid white OLED was fabricated by utilizing a thermally cross-linkable encapsulated TADF molecule. • DVCz-2CzCN possesses good morphologic stability, sufficient solvent resistance and efficient triplet excitons confinement. • The DVCz-2CzCN-based device can afford a high blue TADF OLED by the solution-process with EQE max of 5.6%. • Solution-processed hybrid white OLED exhibits a superior performance with EQE max of 14.9%.