Efficient green organic light-emitting devices based on a solution-processable starburst molecule

We develop high efficiency solution-processed pure green organic light-emitting devices using a starburst molecule 7,7′,7″-(5,5,10, 10,15,15-hexahexyl-10, 15-dihydro-5H-diindeno[1, 2-a:1′, 2′-c]fluorene-2,7,12-triyl)tris(4-(4-(9H-carbazol-9-yl)phenyl)benzo[c][1, 2,5]thiadiazole) (TRcz) doped 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) as the emitting layers. The electroluminescence properties of the devices with different doping concentrations are investigated. With the increasing doping concentration from 0.5wt% to 5wt%, the maximum efficiency changes from 4.8 cd/A to 8.4 cd/A. Under the optimal concentration of 4wt%, the device shows pure green emission at 516 nm with a chromaticity coordinate of (0.30, 0.59) as well as a high brightness of 19900 cd/m² and a high efficiency of 10.1 cd/A, which are better than 11490 cd/m² and 4.2 cd/A obtained in the undoped device.