Toward highly efficient blue organic light-emitting diodes: fabricating a good-quality emissive layer cast from suitable solvents

Spin-cast from various solvents, emissive layers show different film morphologies and performances in solution-processed organic light-emitting diodes (OLEDs). Here we fabricated and demonstrated highly efficient blue OLEDs based on bis[3,5-difluoro-2-(2-pyridyl)phenyl]-(2-carboxypyridy)iridium(iii) by choosing several kinds of solvents for spin-coating. Experiments indicate that the single-layer device with an emissive film cast from chlorobenzene shows its best performance with a highest current efficiency of 18.99 cd A(-1), a maximum luminance of 20.5 × 10(3) cd m(-2) and an emission band centered at 474 nm. The efficiency achieved is the highest reported for solution-processed simple-manufactured OLEDs doped with transition metal phosphors emitting in the blue region.