Enhanced performances of fully solution-processed OLEDs via introducing flexible chains into thermally cross-linked thermally activated delayed fluorescent materials

Abstract

Solution-processable thermally activated delayed fluorescent (TADF) materials have received tremendous attentions due to high exciton utilization, easily scalable large-scale applications. Herein, Thermal cross-linking technology is used to process carbazolyl cyanobenzene (CzCB) derivatives to construct solution-processable thin film networks. We synthesized two novel materials 3CzCN-DV and 3CzCN-O-DV, which could be tightly or loosely cross-linked through varying introduction of flexible alkyl chains. For 3CzCN-O-DV with core-dendron structure, thermal cross-linking in the dendrons was found to preserve the emissive color integrity compared to 3CzCN-DV and allowed for facile solution processing owing to more uniform film morphology. Furthermore, the decreased cross-linking temperature was shown to be advantageous for fabrication of solution-processed OLEDs whose performance was far beyond cross-linked devices based on 3CzCN-DV. This provides a novel method for systematic design of low-temperature cross-linkable luminescent materials, which pave the way for fabrication of fully solution-processed OLEDs that require solution-processable multilayer thin films.