Stable organic light-emitting diodes based on thioxanthone derivative with shortened photoluminescence delayed lifetime

The device stability of the devices based on thermally active delayed fluorescence is still unsatisfactory, although their efficiencies of the reported devices have reached those of phosphorescent emitters for application. Reducing the triplet related nonradiative process is the most efficient method to enhance the device stability. In this work, we designed and synthesized a TADF molecule 4,5-TXO-PhCz with a reduced delayed fluorescence lifetime of only 11.3 mu s. Based on this molecule, the OLED device can reach a maximum EQE of 18.6% with a low efficiency roll-off, the device can even retain 9.38% at luminescence of 5000 cd/m(2). The short PL delayed lifetime suppressed the triplet-related nonradiative annihilation and reduced the efficiency roll-off, affording an excellent device stability with a half lifetime of 380 h. These results indicate that reducing the delayed fluorescence lifetime can effectively reduce the device efficiency roll-off and improve the device stability.

Automated summary

The stability of devices based on thermally active delayed fluorescence is still unsatisfactory, but reducing the delayed fluorescence lifetime can effectively enhance device stability and reduce efficiency roll-off.