Impact of Interface Mixing on the Performance of Solution Processed Organic Light Emitting Diodes-Impedance and Ultraviolet Photoelectron Spectroscopy Study.

We investigated interfacial mixing of solution-processed organic light-emitting devices (OLEDs) using impedance spectroscopy (IS) and ultraviolet photoelectron spectroscopy (UPS) and its impact on device performance. We focused on interfacial mixing between a solution-processed cross-linkable hole transport layer (XM) and an emitting layer (EML), formed either by solution processing or vacuum evaporation. The results of IS and UPS clearly indicated that extensive interfacial mixing was unavoidable, even after the XM was cross-linked to make it insoluble and rinsed to remove residual soluble species, if the subsequent EML was solution processed.

Synthesis of Soluble Host Materials for Highly Efficient Red Phosphorescent Organic Light-Emitting Diodes.

New soluble host materials with benzocarbazole and triphenyltriazine moieties, 11-[3-(4,6-diphenyl-[1,3,5]triazin-2-yl)-phenyl]-11H-benzo[a]carbazole and 11-[3'-(4,6-diphenyl-[1,3,5]triazin-2-yl)-biphenyl-4-yl]-11H-benzo[a]carbazole, were synthesized for highly efficient red phosphorescent organic light-emitting diodes (PHOLED). Hole-transporting benzocarbazole moiety and electron transporting triphenyltriazine moiety, which are severely twisted each other enhance the solubility of those materials in common organic solvent. The improved solubility from this molecular design could be due to a reduced π-π stacking interaction, which gives a very uniform film morphology after spin coating of those materials.

Reproductive isolation between Anopheles sinensis and Anopheles pullus in Korea.

Anopheles sinensis and An. pullus, the 2 predominant anopheline mosquito species in Korea, are major malaria vectors. Their morphological similarity makes them difficult to distinguish, and their taxonomic relationship remains unclear.