Inkjet printing of blue phosphorescent light-emitting layer based on bis(3,5-di(9H-carbazol-9-yl))diphenylsilane

In this study, micropatterning of a blue light emitting, tetraphenylsilane-based phosphorescent material by inkjet printing was investigated. Bis(3,5-di(9 H -carbazol-9-yl))diphenylsilane (SimCP2) doped with iridium bis(4,6-difluorophenypyridinato)picolate (FIrpic) was dissolved in a solvent mixture, and various conditions for the solvent composition and drying of films were examined. Homogeneous dot and line patterns with controllable thickness and smooth surface were obtained from a mixture of chlorobenzene and cyclohexanone at a moderate printing speed of 3 mm s −1 and a droplet ejection frequency of 70 Hz. An inkjet-printed device was designed and fabricated in [ITO/PEDOT:PSS /PVK/SimCP2:Flrpic/TSPO1/TPBi/LiF/Al] configuration, from which sky-blue light (0.14, 0.25) was obtained with a luminous efficiency of 10.73 cd A −1 and a power efficiency of 6.13 lm W −1 . This amounted to 68% of the performance of an identical device where the emitting layer was spin coated. These results show the potential of inkjet printing as a low-cost patterning method for low molecular weight emitters in blue light emitting devices. This study demonstrates successful inkjet printing of SimCP2 doped with FIrpic for applications in large area blue phosphorescent OLEDs.