A quick operating organic EL device using Ru complex light-emitting layer with 2,5-bis(4-tert-butyl-2-benz-oxazolyl) thiophene electron transport layer

Recently, solid-state light-emitting devices based on small molecules such as Ru(bpy)(3)(PF6)(2) and its derivatives attracted attention as electro lu minescence (EL) materials because the luminance shows as high as 1600 cd m( -2) at only 5 V with spin-cast films in air without sealing the devices. De vices based on these materials operate at low voltage (2.5-5 V), however, r esponse of light emission after applying voltage is rather slow, suggesting a similar mechanism with liquid electro-generated chemiluminescence (ECL) cells. In this paper, we added thin electron transporting layer, 2,5-bis(5- tert-butyl-2-benz-oxazolyl) thiophene (BBOT) film (ca. 200 nm) between Ru c omplex light-emitting layer and A1 electrode. As a result, much quicker res ponse was achieved than the ruthenium(II) complex EL devices without adding the BBOT electron transporting layer. (C) 2001 Elsevier Science B.V. All r ights reserved.