Tailoring the molecular design of twisted dihydrobenzodioxin phenanthroimidazole derivatives for non-doped blue organic light-emitting devices

摘要

Three fused polycyclic aryl fragments, namely, naphthyl, methoxynaphthyl, and pyrenyl have been used to construct blue-emissive phenanthroimidazole-functionalized target molecules, i.e. , 1-(2,3-dihydrobenzo[ b ][1,4]dioxin-6-yl)-2-(naphthalen-1-yl)-1 H -phenanthro[9,10- d ]imidazole ( 1 ), 1-(2,3-dihydrobenzo[ b ][1,4]dioxin-6-yl)-2-(1-methoxynaphthalen-4-yl)-1 H -phenanthro[9,10- d ]imidazole ( 2 ), and 1-(2,3-dihydrobenzo[ b ][1,4]dioxin-6-yl)-2-(pyren-10-yl)-1 H -phenanthro[9,10- d ]imidazole ( 3 ). The up-conversion of triplets to singlets via a triplet–triplet annihilation (TTA) process is dominant in these compounds due to 2 E _(T1) > E _(S1) . The pyrenyl dihydrobenzodioxin phenanthroimidazole ( 3 )-based nondoped OLED exhibits blue emission (450 nm) with CIE (0.15, 0.14), a luminance of 53?890 cd m ~(?2) , power efficiency of 5.86 lm W ~(?1) , external quantum efficiency of 5.30%, and current efficiency of 6.90 cd A ~(?1) . The efficient device performance of pyrenyl dihydrobenzodioxin phenanthroimidazole is due to the TTA contribution to the electroluminescent process.