Thermally Cross-Linkable Styrene-Based Host Materials for Solution-Processed Organic Light-Emitting Diodes

: Thermally cross-linkable host materials, DV-TPACZ, DV-TPADBCZ, and TV-TPBI, were designed and synthesized for solution-processed organic light-emitting diodes (OLEDs). The synthesized styrene-functionalized host materials were thermally cross-linked by curing at 150-200 °C without using a polymerization initiator. Excellent solvent resistance was observed for all cured host films. They exhibited low highest occupied molecular orbital energy levels of 5.4-5.7 eV, which indicated a low hole injection barrier from the hole transport layer to the emissive layer. A solution-processed red phosphorescent OLED with 5 wt% (MPHMQ)₂Ir (tmd) dopant in the thermally cross-linkable DV-TPACZ host exhibited a current efficiency of 5.3 cd/A, power efficiency of 3.2 lm/W, and external quantum efficiency of 3.6%.