A new spiro-type compound, 2-(10-biphenylanthracene)-spirofluorene-7,9′-benzofluorene (BH-3B) containing anthracene moiety was prepared for the blue host material. Also new dopant materials, ...2-4′-(phenyl-4-vinylbenzeneamine)phenyl-spirofluorene-7,9′-benzofluorene (BH-3BD) and 4-2-naphthyl-4′(phenyl-4-vinylbenzeneamine)phenyl (BD-1N) were successfully synthesized and a blue OLEDs were made from them. The structure of the device was as follows; ITO/DNTPD/
α-NPD/Host:5% dopant/Alq
3/Al-LiF. Among all of the devices, the device obtained from BH-3B host doped with 5% BH-3BD showed the best electroluminescence characteristics. The emission peak of EL is at 456
nm and the CIE value is (0.15,
0.14). The brightness of the device is up to 5407
cd/m
2 at 10
V with the maximum EL efficiency of 3.4
cd/A.
The deep blue fluorescent spiro-type dopant materials
N,N,N′
,N′-tetraphenylspirofluorene-7,9′-benzofluorene (
SFBF)-5,9-diamine (BD-6DPA),
N,N′-di-(2-naphthyl)-
N,N′-diphenyl-
SFBF-5,9-diamine ...(BD-6NPA),
N,N′-diphenyl-
N,N′-di-
m-tolyl-
SFBF-5,9-diamine (BD-6MDPA) and
N,N′-diphenyl-
N,N′-bis(4-(trimethylsilyl)phenyl)-
SFBF-5,9-diamine (BD-6TMSA) were designed and successfully prepared by amination reactions. The EL characteristics of MADN as the blue host material doped with the above blue dopant materials were evaluated. The electroluminescence spectra of ITO/
N,N′-diphenyl-
N,N′-bis-4-(phenyl-
m-tolyl-amino)-phenyl-biphenyl-4,4′-diamine (DNTPD/
N,N′-di(1-naphthyl)-
N,N′-diphenylbenzidine (NPB)/2-methyl-9,10-di(2-naphthyl)anthracene (MADN):BD-6MDPA/tris(8-hydroxyquinoline)aluminum (Alq
3)/LiF/Al devices show a narrow emission band with a full width at half maximum of 48
nm and a
λ
max(
ε)
=
463
nm. The device obtained from MADN doped with BD-6MDPA showed a good color purity (0.135, 0.156), high luminance efficiency (9.11
cd/A at 6.5
V) and high external quantum efficiency (8.16%).
Thermally stable blue organic light-emitting diodes (OLEDs) were developed using anthracene based host materials with a spirobifluorene group. 4-Bromospirobifluorene and 2-bromospirobifluorene were ...attached to the anthracene core and the effect of the substitution position on the physical properties and device performances of the blue fluorescent OLEDs was investigated. The 4-spirobifluorene substitution was better than the 2-spirobifluorene substitution in terms of thermal stability and widened the bandgap of the anthracene based host material due to the geometrical structure of the material. However, the wide bandgap of the host material with 4-spirobifluorene had negative effect on the current density and efficiency of the blue devices.
Although remarkable progress has been made in the field of blue organic light-emitting diodes (OLEDs), many challenges persist. In particular, the emitting material layer of an OLED is composed of a ...host and a dopant, and the host material has a significant influence on the device efficiency and lifetime along with the dopant. Therefore, in this study, 9-(2′-(dibenzob,dfuran-4-yl)-1,1′-biphenyl-3-yl)-9H-carbazole, 3′-(9H-carbazol-9-yl)-2-(dibenzob,dfuran-4-yl)-1,1′-biphenyl-3-carbonitrile, and 3′-(9H-carbazol-9-yl)-2-(dibenzob,dfuran-4-yl)-1,1′-biphenyl-4-carbonitrile were synthesised to investigate the changes in the device efficiency and lifetime through various properties such as the polarity of the host molecule and anionic bond dissociation energies (BDEs) according to the substitution position of the CN group. In addition, 2,4,6-tris(2-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)-1,3,5-triazine, a blue thermally activated delayed fluorescence dopant, was synthesised and evaluated. The roll-off at 5000 nit decreased from 30.2% to 21.9% depending on the polarity of the host molecule, whereas the lifetime increased from 7.95 to 15.5 h according to the anionic BDE of blue thermally activated delayed fluorescence hosts.
•New host materials were designed and synthesized, and then applied to a blue TADF OLED device to evaluate its performance as a host.•The blue TADF material 2,4,6-tris(2-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)-1,3,5-triazine (TtBCz-Trz) was synthesised and evaluated using the developed hosts.•Device efficiency and lifetime through various properties such as the polarity of the host molecule and anionic bond dissociation energies (BDEs) according to the substitution position of the CN group.•The roll-off at 5000 cd/m2 decreased from 30.2% to 21.9% depending on the polarity of the host molecule, whereas the lifetime at 200 cd/m2 increased from 7.95 to 15.5 h according to the anionic BDE of blue TADF hosts.
A novel, spiro-type host material 2-(10-naphthylanthracene)-spirofluorene-7,9′-benzofluorene was prepared by reacting 2-bromo-spirofluorene-7,9′-benzofluorene with 9-(2-naphthylanthracene)-10-boronic ...acid via the Suzuki reaction. 2-4′-(Phenyl-4-vinylbenzeneamine)phenyl-spirofluorene-7,9′-benzofluorene, 4-2-naphthyl-4′(phenyl-4-vinylbenzeneamine)phenyl and diphenyl-4-(2-1,1;4,1terphenyl-4-yl-vinyl)-phenyl-amine were used as dopant materials. Devices with the configuration of ITO/
N,
N′-bis4-(di-
m-tolylamino)phenyl-
N,
N′-diphenylbiphenyl-4,4′-diamine)/bis
N-(1-naphthyl)-
N-phenylbenzidine/2-(10-naphthylanthracene)-spirofluorene-7,9-benzofluorene:5% dopant/aluminum tris(8-hydroxyquinoline)/Al-LiF showed a maximum power efficiency of 3.7
cd/A at 17.93
mA/cm
2 and a maximum luminance of 5018
cd/m
2 at 10
V with a turn-on voltage of 4.5
V.
PDF
