High-efficiency white OLEDs based on small molecules

Hatwar, T. K.; Spindler, Jeffrey P.; Ricks, Michele; Young, Ralph H.; Hamada, Y.; Saito, Nobuo; Mameno, Kazunobu; Nishikawa, Robert M.; Takahashi, Hisakazu; Rajeswaran, G.

doi:10.1117/12.514536

Cited by 21 publications

(28 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More recently, white-light-emitting fluorescent OLEDs with a luminescence yield in excess of 12 cd A ±1 have been produced; however, the device requires a relatively complex layer structure. [53] In any event, an achromatic polarizer for the generation of polarized white light from an unpolarized source works at a typical energy efficiency of 40 %. [54] Thus the performance of our polarized white-light OLED compares favorably with these high-efficiency white-light unpolarized OLEDs.…”

Section: ±1mentioning

confidence: 99%

Organic Polarized Light‐Emitting Diodes via Förster Energy Transfer Using Monodisperse Conjugated Oligomers

et al. 2004

View full text Add to dashboard Cite

A heptafluorene lightly doped with monodisperse conjugated oligomers is used for the first demonstration of organic polarized (see Figure) light‐emitting diodes utilizing Förster energy transfer. Emission of blue‐green, green, red, and white light is accomplished with a turn‐on voltage of < 4 V, peak polarization ratios of up to 26, integrated polarization ratios of up to 19, and luminance yields of up to 6.4 cd A–1.

show abstract

Section: ±1mentioning

confidence: 99%

Organic Polarized Light‐Emitting Diodes via Förster Energy Transfer Using Monodisperse Conjugated Oligomers

et al. 2004

View full text Add to dashboard Cite

show abstract

“…1. Based on the understanding of the conduction properties of Ir(ppy) 3 and btp 2 Ir(acac)-doped CBP layers, we optimized the sequence of three primary colour EMLs of the multi-layer white OLEDs in which CBP layers doped with the phosphorescent dopants Ir(ppy) 3 and btp 2 Ir(acac), and the fluorescent dopant DPAVBi, were used as green (G), red (R), and blue (B) EMLs, respectively. Furthermore, we discuss the effect of the R, G, B EML sequences on the accelerated lifetime of devices.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we systematically studied the electrical conduction properties of iridium-based green and red phosphorescent emitters, fac-tris(2-phenylpyridine) iridium(III) (Ir(ppy) 3 ) and bis(2-(2´-benzo[4,5-a]thienyl)pyridinato-N,C3´)iridium(acetyl-acetonate) (btp 2 Ir(acac)), doped in the host of 4,4'-N,N'-dicarbazolebiphenyl (CBP) since CBP is commonly used as a host in green/red-doped phosphorescent OLED. The molecular structures and the relevant energy levels of the green and red phosphorescent materials doped in CBP are shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…White organic light-emitting diodes (WOLEDs) have become a recent research focus due to their applications to fullcolor displays, backlights, and solid-state lightings [1][2][3][4] White light emission requires mixing of different colors from the multilayer structure of several emitting layers. Careful control of doping concentration and the thickness of each emitting layer, interlayers, or electron and hole blocking layers is necessary to obtain a balanced white emission.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optimization of white OLEDs based on charge carrier conduction properties of phosphorescent emitting layers

Lee¹,

Baek

Kwak

et al. 2008

SPIE Proceedings

View full text Add to dashboard Cite

The charge conduction properties of the organic phosphorescent emission layer doped with iridium-based green and red phosphorescent emitters, fac-tris(2-phenylpyridine) iridium(III) (Ir(ppy) 3 ) and bis(2-(2´-benzo[4,5-a]thienyl)pyridinato-N,C3´)iridium(acetyl-acetonate) (btp 2 Ir(acac)), were studied and compared to those of the reference host of 4,4'-N,N'-dicarbazole-biphenyl (CBP). In the CBP host layer, both dopants act as hole traps but they affect the electron transport differently. Compared with the pristine CBP film, the electron mobility is similar for Ir(ppy) 3 -doped CBP but it is more than two orders of magnitude lower for btp2Ir(acac)-doped CBP. Because of such difference in the electrical conduction properties between the Ir(ppy) 3 -and btp 2 Ir(acac)-doped CBP, the main recombination zone position and the electron-hole balance changes. Based on these findings, we optimized white organic light emitting diodes (OLEDs) with multi-emitting layer (EML) structures in which CBP layers doped with Ir(ppy) 3 and btp 2 Ir(acac) and fluorescent dopant of 4,4´-bis[2-{4-(N,N-diphenylamino)phenyl}vinyl]biphenyl (DPAVBi) were used as green (G), red (R), and blue (B) EMLs, respectively. The white OLEDs with the R/G/B EML sequence show improved electron and hole balance, resulting higher efficiency, better color stability and longer lifetime compared to the G/R/B EML sequence. A high luminous current efficiency of 13.5 cd/A at 100 cd/m 2 was achieved with the R/G/B EML sequence.

show abstract

“…Especially, white light emitting diode (WOLED) is getting more important for their potential applications in high quality and large area flat panel displays with color filters and an alternative lighting source. [1][2][3][4] The combination of white OLED and a color filter has an advantage since it does not require so much accurate alignment as separately depositing red, green and blue pixels.…”

Section: Introductionmentioning

confidence: 99%

Harvest of triplet excitons in fluorescence emission layer based on a wide band gap host of TcTa for efficient white organic light emitting diodes

et al. 2007

View full text Add to dashboard Cite

Selective energy transfer from triplet states of the fluorescent blue emission layer to a red phosphorescent dye in a neighbored triplet harvesting layer has been achieved, which has provided improved efficiency with emissions from fluorescent and phosphorescent dyes. First of all, it is crucial to find a wide band gap host for a fluorescent blue emission layer which has larger triplet state band gap than green or red phosphorescent dye. It was found that TcTa is a good wide band gap host for fluorescent blue dopant(BD) and a efficient blue device was obtained. A phosphorescent red dopant (RD) was introduced into a neighboring electron transporting layer to harvest triplet states in the fluorescent blue emission layer and by optimizing the distance between the blue emission layer and the red triplet harvesting layer, we have succeeded in obtaining the balanced emission of the blue and the red emissions with high efficiency from the device structure of NPB/TcTa:BD/BAlq/BAlq:RD/BAlq/LiF/Al. The device showed maximum external quantum efficiency of 16 % at 0.1 mA/cm 2 and 13 % of external quantum efficiency, (0.29, 0.23) of CIE coordinates and 920 cd/m 2 at 10 mA/cm 2 . To realize RGB WOLED, a fluorescent green dopant was introduced into the blue emission layer. The RGB WOLED was successfully obtained through optimization of doping concentration for green dopant and it showed 10 % of external quantum efficiency, (0.36, 0.36) of CIE coordinates and 1400 cd/m 2 at 10 mA/cm 2 .

show abstract

High-efficiency white OLEDs based on small molecules

Cited by 21 publications

References 0 publications

Organic Polarized Light‐Emitting Diodes via Förster Energy Transfer Using Monodisperse Conjugated Oligomers

Organic Polarized Light‐Emitting Diodes via Förster Energy Transfer Using Monodisperse Conjugated Oligomers

Optimization of white OLEDs based on charge carrier conduction properties of phosphorescent emitting layers

Harvest of triplet excitons in fluorescence emission layer based on a wide band gap host of TcTa for efficient white organic light emitting diodes

Contact Info

Product

Resources

About