Optoelectronic Devices Based On Ir-complexes

A great deal of progresses have been made on obtaining high electroluminescence performances due to useing of both the singlet and triplet excitons, and a maximum internal efficiency of 100% in phosphorescence devices could be harvested. Since 1998, when the first phosphorescence device had been made, organic metal complexes have drawn much attention in organic electronics. In this work, organic optoelectronic devices, including organic light-emitting diodes (OLEDs) and organic photovoltaic (OPV) devices based on Ir-complex were prepared to investigate their device physics and improve their performances.We demonstrated a considerable increase in current efficiency of fac-tris(2-phenylpyridine) iridium doped phosphorescent organic green-light emitting diode in which a thin 4,7 dipheny-1,10-phenanthroline (Bphen) layer acts as a cleaving layer. A maximum current efficiency of 53 cd/A was obtained, which was higher for 2.3 folds than that of the device without it. The efficiency improvement attributed to a higher exciton formation probability in the recombination zone and better balance of the carrier injection.We made a high-efficiency electrophosphorescent device doped with bis(2-phenyl-benzoimidazole) iridium (III) acetylacetonate with a triplet lifetime in the range of nanoseconds. The doped mixed host was sandwiched by two doped single-host layers. Multi-recombination zones were formed in the emission layer. Such a structure could increase the proportion of recombined carriers to injected carriers and extend the recombination zone. As a result, a maximum external quantum efficiency of 18.6% was attained due to the presence of multi-recombination zones.We demonstrated a enhanced power conversion efficiency (PCE) of a OPV by doping 4 wt % IrC₆ phosphor into C60 accepter layer in CuPc/C60 OPV diode, here IrC₆ is iridium(III) bis(3-(2-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-onato-N',C4) (acetyl acetonate). The increase in PCE by doping IrC₆ was attributed to energy and/or electron transfers from IrC₆ to C60 species, presence of a IrC₆/ C60 sub-PV cell, as well the rising absorption of IrC₆ in the cell at 400-500 nm waveband. The Increase in PV response mainly came from the enhanced photocurrent density of the PV cell.