Synthesis Of Per-Deuterated Tris(2-phenylpyridine)Iridium For Highly Stable Electrophosphorescence: The "Heavy Deuterium Effect"

In recent years, the rapid development of OLED has brought a new dawn for flat panel display, there is no longer doubt that the era of OLED will be coming. However, comparing with the traditional display industry, OLED technology still is at the early stage. OLED that is as a solid light source is promising in the displays due to their potential advantages in low driving voltage, small size, long life and so on, but there is a fatal difficulty that should not be neglected, the poor device stability makes it difficult to be used in daily life widely. Many researchers have been focused on improving the stability of the device. Organic thin film electroluminescent will be promising once the stability problem is resolved. This article is mainly synthesized deuterated green phosphorescent iridium complexes and blue phosphorescent iridium complexes auxiliary ligand by the exchange of C-H and C-D. Exchanging the C-H for C-D vibrational oscillators reduced the nonradiative deactivation as a result of reduced probability of vibronic coupling between the states, which contributes to improving the stability of the device. The main contents are as follows:1. By starting from the very simple and not expensive reagent, deuterated benzene, we obtained deuterated bromobenzene, and then by reacting deuterated bromobenzene with another simple and not expensive regent, deuterated pyridine. we obtained deuterated 2-phenylpyridine. Then after, we obtained deuterated tris(2-phenylpyridine)iridium by using this ligand. And the correspondent normal tris(2-phenylpyridine)iridium is prepared with the same methods. By contrast, we fond that the device stability of under high current densities has been greatly improved (about 20 times) and the device lifetime been greatly extended through deuteration of the 2-phenylpyridine (about 6 times). It can provide new sights to solve the stability issue. The deuteration can be used as a prototype for all electrophosphorescent devices, which will improve the speed of OLEDs in daily life.2. By starting from the very simple but not expensive reagent, deuterated pyridine. we obtained deuterated 2-picolinic acid that is the auxiliary ligand of the deuterated Firpic, deuterated 2-bromopyridine that is the precursor of the main ligand 2-(2,4-difluorophenyl)pyridine.Which laids the foundation for the preparation of deuterated FIrpic. In addition, we obtained deuterated 2-(2,4-difluorophenyl)pyridine through deuterium exchange, then after we obtained deuterated Firpic by using this main ligand and the auxiliary ligand. And the study of the device properties will be soon performed.