Blue-emitting Ir(iii) phosphors with 2-pyridyl triazolate chromophores and fabrication of sky blue- and white-emitting OLEDs

Abstract

Heteroleptic Ir(III) complexes with 3-tert-butyl-5-(2-pyridyl)-1,2,4-triazolate chromophore (bptz) and cyclometalating benzyldiphenylphosphine (bdp) or phenyl diphenylphosphinite (pdpit) ancillary (i.e.[Ir(bptz) 2 (bdp)] (1) and [Ir(bptz) 2 (pdpit)] (2)) are synthesized upon treatment of [IrCl 3 (tht) 3 ] (tht ¼ tetrahydrothiophene) with the relevant phosphine, followed by the addition of 2 equiv. of bptz chelate at elevated temperature. Their photophysical properties in solution were measured, along with the characteristics detected as dopants in thin solid films. For application, organic light emitting diodes (OLEDs) were also fabricated using 1 and 2 as dopants, achieving respective maximum efficiencies of 17.8% (44.8 cd A À1 and 46.3 lm W À1 ) and 9.1% (22.8 cd A À1 and 23.6 lm W À1 ). In addition, sky blue iridium complex 1 was used with red osmium complex [Os(bpftz) 2 (PPhMe 2 ) 2 ] (3) to fabricate phosphorescent OLEDs with a sophisticated red/blue/red emitting layer architecture, attaining a stable warm white color with CIE coordinates of (0.397, 0.411). This white OLED attained an electroluminescence efficiency of up to 18.1%, 39.6 cd A À1 , and 35.7 lm W À1 for the forward direction.

Deep-blue phosphorescent iridium(III) dyes based on fluorine-functionalized bis(2,3′-bipyridyl) ligand for efficient organic light-emitting diodes

“…Therefore, the high emission quantum yield of 1 can be attributed to both the enhancement of radiative decay processes and the restriction of various metal-ligand stretching motion, which are due to strong metal ion-ligand interactions (see the bond lengths of 1 in the crystal structure). [9] Cyclic voltammetry experiments for all compounds were carried out in order to estimate HOMO levels under the same experimental conditions. All compounds displayed a single reversible Consequently, electrochemical stability, as well as high PL quantum efficiencies, qualifies all four compounds as suitable candidates for use in deep-blue PHOLEDs.…”

Efficient fluorescence/phosphorescence white organic light-emitting diodes with ultra high color stability and mild efficiency roll-off

“…The efficiency of most of the reported highly efficient WOLEDs even drops to single digit at high brightness of 5000 or 10 000 cd/m 2 . [17][18][19] Besides, the spectra of most of the reported WOLEDs usually exhibits a big change with different brightnesses, which implies that the color of the WOLEDs under the maximum luminous efficiency is not really white emission as some reports suggest.…”

Bis-Tridentate Iridium(III) Phosphors Bearing Functional 2-Phenyl-6-(imidazol-2-ylidene)pyridine and 2-(Pyrazol-3-yl)-6-phenylpyridine Chelates for Efficient OLEDs

“…17 Hence, the installed HTL and the ETL have provided good confinement and avoided the exciton diffusion to the adjacent layers. 18 The slight variation in EL in both devices is mainly due to the different optical interference.…”