All-small-molecule efficient white organic light-emitting diodes by multi-layer blade coating

Abstract

Blue and white small-molecule organic light-emitting diodes are fabricated by multi-layer blade coating on hot plate at 80 °C with hot wind. Uniform multi-layer structures are made without dissolution due to rapid drying. Only small molecules originally developed for vacuum deposition are used. For hole transport layer of, 4′,4″-tris(carbazol-9-yl)triphenylamine (TCTA), electron transport layer of 2,2′,2″-(1,3,5-benzinetriyl)-tris(1- phenyl-1-H-benzimidazole) (TBPI), emissive layer host of, 6-bis(3-(9H-carbazol- 9-yl)phenyl)pyridine (26DCzPPy), triplet emitters of bis(3,5-difluoro-2-(2- pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (FIrpic), and cathode of LiF/Al, the peak current efficiency for blue emission is 25.1 cd/A (10.8% and 9.3 lm/W). Orange emitter iridium(III)bis (4-(4-t-butylphenyl) thieno[3,2-c]pyridinato-N, C2′)acetylacetonate (PO-01-TB) is added to obtain white emission with CIE coordinate of (0.39, 0.46) [1]. The current efficiency is 34.2 cd/A (11.6% and 12 lm/W) at maximum, 32.4 cd/A at 1000 cd/m2, and 31 cd/A at 10,000 cd/m2. © 2012 Elsevier B.V. All rights reserved.