Control of excimer phosphorescence by steric effects in cyclometalated platinum(ii) diketonate complexes bearing peripheral carbazole moieties towards application in non-doped white OLEDs?

New Journal of Chemistry Pub Date: 2018-05-25 DOI: 10.1039/C8NJ01526K

Abstract

Novel cyclometalated platinum(II) complexes bearing peripheral carbazole moieties were synthesized, aimed at fabrication of non-doped white organic light-emitting diodes (OLEDs) by utilizing excimer-based electroluminescence (EL). The complexes exhibited monomer and excimer emissions in the film state, and their ratios were varied by the steric hindrance of the cyclometalated and ancillary ligands. Using the platinum(II) complexes as an emitting layer, non-doped multilayer OLEDs were fabricated by solution processing, where all the organic layers were prepared by taking advantage of the solubility and insolubility of the complexes in cyclohexane and methanol, respectively. The devices using the acetylacetonate complexes exhibited predominantly excimer-based orange EL, whereas the dipivaloylmethanate complexes exhibited white EL with Commission internationale de l'éclairage chromaticity coordinates of (0.37, 0.41) and (0.35, 0.40), accompanied by a high average color rendering index of 81 due to the balanced blue monomer and orange excimer emissions.

Graphical abstract: Control of excimer phosphorescence by steric effects in cyclometalated platinum(ii) diketonate complexes bearing peripheral carbazole moieties towards application in non-doped white OLEDs
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