Abstract
Significant improvement in electroluminescent performance was resulted by incorporating nano-dots in the small-molecule host composing and solution-processing emission layers for red, green, blue and white organic light-emitting devices (WOLEDs). The proper nano-dot was cadmium selenium (CdSe) prepared in organic solvent, which was miscible with the host solutions of 4,4?-bis (carba- zol-9-yl) biphenyl (CBP) doped with red dye of bis [2-(2?-benzothienyl)-pyridinato-N,C3?] (acetyl-acetonate) iri-dium (III), green dye of tris(2-phenylpyridine) iridium (III) and/or blue dyebis(3,5-difluoro-2-(2-pyridyl)-phenyl-(2-carboxypyridyl) iri- dium (III). The power efficiency of the red OLEDs increased from 1.7 to 2.5 lm/W on the addition of 0.006 wt% CdSe. For the green OLEDs, it increased from 7.8 to 9.9 lm/W by adding 0.006 wt% CdSe. For the blue OLEDs, it increased from 1.45 to 1.66 lm/W by adding 0.01 wt% CdSe. The incorporation effect of CdSe was the most marked on the red device and the least on the blue device; i.e. that the power efficiency increment was 47% for the red device and 14.5% for the blue device. For the WOLEDs, it changed from 3.9 to 4.5 lm/W with a 15.4% increase in power efficiency as 0.002 wt% CdSe was incorporated, accompanied by a 5.7% increase in the resulted maximum luminance.