Thermally cross-linkable thermally activated delayed fluorescent materials for efficient blue solution-processed organic light-emitting diodes

Abstract

Solution-processed organic light-emitting diodes (OLEDs) have attracted great attention due to their simple fabrication process and easy scalability of the solution process. In this work, a thermally cross-linkable thermally activated delayed fluorescent (TADF) molecule DV-MOC-DPS was designed and synthesized. Moreover, a thermally cross-linkable host material DV-CDBP with high triplet energy was also synthesized. With the incorporation of two cross-linkable vinylbenzyl ether groups, both these materials with excellent thermal stabilities can be fully cross-linked after heating at 180 °C. In addition, the cross-linked films with the different mass ratios of DV-CDBP and DV-MOC-DPS (1 : 0.06, 1 : 0.09 and 1 : 0.12) were investigated. The cross-linked films are quite smooth with the root-mean-square (RMS) roughness in the range from 0.622 nm to 0.725 nm. Simultaneously, the cross-linked film with a mass ratio of 1 : 0.09 exhibits the highest photoluminescence quantum yield of 0.71. By employing the cross-linked films as emitting layers, an efficient blue solution-processed OLED with a maximum external quantum efficiency of 2.0% was achieved. The molecular design reported here provides a novel route toward highly efficient solution-processed OLEDs.