Dimeric SFX host materials for red, green and blue phosphorescent organic light-emitting devices

Two novel spiro[fluorene-9,9'-xanthene]-based derivatives 23'ODSFX and 3'3'ODSFX, without possessing conventional hole- or electron-transporting units, have been synthesized by a simple reaction procedure and been demonstrated to be host materials for efficient and low-voltage blue, green and red phosphorescent organic light-emitting devices (PHOLEDs). They showed good thermal stability with high glass transition temperatures (T-g) at 210 degrees C for 23'ODSFX and 138 degrees C for 3'3'ODSFX Compared with SFX-based devices, the performance of 23'ODSFX-based devices increased nearly 20 times, although the difference of HOMO/LUMO levels and triplet levels between dimeric SFX and SFX was very small. The blue PHOLEDs based on 23'ODSFX and 3/3/ODSFX exhibited the same low turn-on voltage of similar to 2.6V, and maximum current efficiency (CE) of 21.7/12.9 cd cd A(-1), power efficiency (PE) of 19.5/11.5 lm W-1, and external quantum efficiency (EQE) of 11.9%/7.2%, respectively. It was evident that the different position linkage in host materials was closely relative to the device performance. (C) 2014 Elsevier B.V. All rights reserved.