Fast synthesis of iridium(iii) complexes with sulfur-containing ancillary ligand for high-performance green OLEDs with EQE exceeding 31%?

Journal of Materials Chemistry C Pub Date: 2019-05-07 DOI: 10.1039/C9TC01397K

Abstract

Three green iridium(III) cyclometalated complexes, namely, (4tfmppy)2Ir(dipdtc), (24btfmppy)2Ir(dipdtc), and (TN4T)2Ir(dipdtc), with the sulfur-containing ancillary ligand N,N-diisopropyldithiocarbamate (dipdtc) were synthesized within 15 min at room temperature. The emission colors (λpeak = 497–534 nm) and photoluminescence quantum efficiencies (ΦP = 71.6–94.2%) can be effectively regulated by introducing different main ligands, namely, 2-(4-(trifluoromethyl)phenyl)pyridine (4tfmppy), 2-(2,4-bis(trifluoromethyl)phenyl)pyridine (24btfmppy), and 2′,6′-bis(trifluoromethyl)-2,4′-bipyridine (TN4T). Employing these complexes as emitters, organic light-emitting diodes (OLEDs) with double-emitting layers were fabricated. In particular, the device based on the (TN4T)2Ir(dipdtc) complex showed superior performances with maximum current efficiency of 86.59 cd A?1 and maximum external quantum efficiency of 31.24% with low efficiency roll-off. These results suggest that the Ir(III) complexes with a four-membered ring Ir–S–C–S backbone containing dipdtc have potential applications in OLEDs.

Graphical abstract: Fast synthesis of iridium(iii) complexes with sulfur-containing ancillary ligand for high-performance green OLEDs with EQE exceeding 31%
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