Bright and ultimately pure red electrophosphorescent diode bearing diphenylquinoxaline

Abstract

Abstract:The ultimately pure red OLED using new electrophosphorescent compound, bis(2,3-diphenylquinoxaline)iridium(acetylacetonate) [(QH) 2 Ir(acac)] is described. Electrophosphorescence peak wavelength and bandwidth were advanced for the purest red color stimulus to 680 nm with full width at half maximum of 89 nm by doping (QH) 2 Ir(acac) into a light emitting electron transport layer composed of 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole. The most vivid red electrophosphorescence with CIE chromaticity coordinates better than x = 0.70 and y = 0.28, which are the closest to the ultimate limit of pure red among reported OLEDs, was attained and maintained even in luminance brighter than 600 cd/m 2 . A very high maximum external electrophosphorescent quantum efficiency of 10.2% was also realized. Keywords: OLED, color purity, pure red, electrophosphorescence Classification: New functional devices and materials Forrest, "Very high-efficiency green organic light-emitting devices based on electrophosphorescence," Appl. Phys. Lett., vol. 75, no. 1, pp. 4-6, July 1999. [7] J. Kido, C. Ohtaki, K. Hongawa, K. Okuyama, and K. Nagai, "1,2,4-Triazole derivative as an electron transport layer in organic electroluminescent device," Jpn. References

Deep-red organic light-emitting diodes with stable electroluminescent spectra based on zinc complex host material

“…28 For deep-red OLEDs, two reasons can attribute to lower efficiency compared to blue, green, orange-red OLEDs: rstly, the nonradiative decay rate of emitter increases when the energy gap is decreasing according to energy gap law; 29 secondly, a drop of luminous ux within the deep-red region and decrease of eye sensitivity among this wavelength range, leads to lower power efficiency compared to green or blue OLEDs. 30 Compared to reported results, 15,17,18 our devices show good performance among deep-red OLEDs, with stable CIE coordinate as high as (0.70, 0.30) even at high current density.…”

“…Fujii et al realized a deep-red OLEDs with EQE of 10.2% and CIE coordinates of (0.70, 0.27), by using a deep-red phosphorescent emitter bis(2,3-diphenylquinoxaline)iridium-(acetylacetone) [(QH) 2 Ir(acac)] and 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ-01) as host. 15 However, the CIE coordinate shied to lower than 0.70 when increasing current density. Jou et al reported a deep-red OLED with [bis(spiro-uorenedibenzosuberene[d]quinoxaline-C 2 ,N)-monoacetyl-cetone]iridium(III) as emitter and N,N 0 -di(naphthalene-1-yl)-N,N 0diphenylbenzidine (NPD) and bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq 2 ) as co-host, achieving maximum EQE of 11.2%, and CIE coordinates of (0.70, 0.27) at 10 cd m À2 .…”

Ring Size Effects on Multi‐Stimuli Responsive Luminescent Properties of Cyclic Amine Substituted β‐Diketones and Difluoroboron Complexes

“…For synthesis of the bdk ligands, the cyclic amine substituted ketones were prepared as previously described . Data for l ‐pyr and l ‐pip , d ‐pip , l ‐azp and d ‐azp , are in accord with previous reports.…”

Computer aided design of stable and efficient OLEDs

“…Considering the individual emitters, at present, there exist stable and efficient triplet emitters for red, [14][15][16][17][18][19][20][21][22][23] green, [24][25][26][27][28][29][30][31][32][33] and yellow (for use in white OLED-TV stacks), with blue falling short. Blue emitters continue to be problematic and many ongoing research efforts target this specifically.…”