High-Efficiency Deep-Blue Solution-Processed OLED Devices Enabled by New Dopant Materials.

Two blue fluorescent dopants were designed and successfully synthesized, 5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho [3,2,1-de]anthracen-7-yl)-5H-benzo[b]carbazole (TDBA-Bz) and 9-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-9H-carbazole (TDBA-Cz). Both in solution and the film state, the two emitters demonstrated deep-blue luminescence characteristics. In solution-processed organic light-emitting diodes (OLEDs), TDBA-Bz and TDBA-Cz used as dopant materials showed electroluminescence peaks at 436 nm and 413 nm, respectively. The corresponding CIE color coordinates were determined to be (0.181, 0.114) for TDBA-Bz and (0.167, 0.086) for TDBA-Cz. The solution-processed device using TDBA-Cz as a dopant exhibited a current efficiency (CE) of 7.25 cd/A and an external quantum efficiency (EQE) of 6.45%, demonstrating higher efficiencies compared to the device with TDBA-Bz. In particular, at a luminance of 2000 cd/m, TDBA-Cz maintained an EQE of 4.81%, with only a slight decrease from its maximum EQE.