A solution-processable deep red molecular emitter for non-doped organic red-light-emitting diodes

A new solution-processable deep red emitter, TCTzC, containing dithienylbenzothiadiazole unit and four alkyl-linked peripheral carbazole groups, is designed and synthesized in high yield by Suzuki coupling reaction. The four peripheral carbazole substituents enhance the hole-transport ability, glass transition temperature, decompose temperature and film forming ability of TCTzC. The single-layered device based on TCTzC shows saturated deep red electroluminescence with a CIE coordinate of (0.70, 0.30). The current efficiency and quantum efficiency of TCTzC is two times higher than the compound without the four peripheral carbazole groups. The higher device performance is obtained when TPBi is applied and the external quantum efficiency could reach to 0.93%.

► A deep red emitter TCTzC was obtained. ► It exhibits good amorphous morphology, high Tg and Td. ► Non-doped solution-processable device shows a saturated red emission. ► The EQEmax is 0.93% with a CIE of (0.70, 0.30).