Dendritic Luminescent Gold(III) Complexes for Highly Efficient Solution-Processable Organic Light-Emitting Devices

摘要

Organic light-emitting diodes (OLEDs) have attracted much attention in the past few decades and are considered as remarkably attractive candidates for flat panel display technologies and solid-state lighting. Phosphorescent heavy-metal complexes, such as iridium (III), platinum(II), ruthenium(II), and osmium (II) complexes, are important classes of materials for making OLEDs because of their high luminescence quantum yields.121 The presence of a heavy-metal center can effectively enhance spin-orbit coupling and promotes an efficient intersystem crossing from its singlet excited state to the triplet excited state, harvesting both singlet and triplet excitons for light emission to realize an internal quantum efficiency of up to 100 %. The performance of multilayer OLEDs based on vacuum-deposited phosphorescent small molecules of iridiurn(III) complexes are very encouraging. However, the architecture of such devices is rather complicated and requires a delicate control of the dopant concentration, thereby leading to a high production cost. The use of solution processing techniques including spin-coating or ink-jet printing to prepare OLEDs is an effective approach to lower the manufacturing cost, especially for large-area displays. Indeed, various classes of small molecules and conjugated polymers have been reported to give highly efficient solution-processable OLEDs.