An organic LED display exhibiting pure RGB colors

Fukuda, Yoshiro; Watanabe, Taeko; Wakimoto, Takeo; Miyaguchi, Satoshi; Tsuchida, Masami

doi:10.1016/s0379-6779(99)00402-6

Cited by 76 publications

(40 citation statements)

References 9 publications

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“…Such observations are attributed to the interference effects due to the changes in the optical path length where the change in EL spectrum is measured at normal to the surface. 19,20 Broadening of the PL spectra on the red side of the emission band was also observed when the device was optically excited; this confirms the cavity interference effect. Optical simulation using SETFOS 3.1 software 21 can qualitatively describe the effect of PVKH on EL spectra emission and also can predict the radiating dipole density location and distribution.…”

Section: B Device Emission Characteristicssupporting

confidence: 56%

“…The lower dark current density measured at thicker PVKH devices indicates an increase in the trapping probability at the complex sites yielding more efficient exciton generation. The electron mobility of the emissive layer [PVKL:PBD:Ir(ppy) 3 ] is dominated by the PBD (2 Â 10 À5 cm 2 /Vs) 20 and is higher than the hole mobility of the PVKH (the measured PVK hole mobility range from 4.8 Â 10 À9 to …”

Section: Electrical Characteristics and Device Performancementioning

confidence: 99%

“…not only on the emissive exciton concentration but also on cavity optimization 19,20 and minimization of other quenching processes such as triplet-exciton quenching (triplet-triplet annihilation and triplet-polaron quenching) [28][29][30] and field induce quenching. 31 The EML layer thickness of 80 6 5 nm gave the highest device efficiency, and is in agreement with the simulation results of Figs.…”

Section: -4mentioning

confidence: 99%

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Solution processed multilayer polymer light-emitting diodes based on different molecular weight host

Al-Attar

Monkman

2011

Journal of Applied Physics

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Solution processed multilayer polymer light-emitting diodes (PLEDs) based on different molecular weight host have been investigated. A PLED based on high molecular weight poly (vinyl carbazole) PVKH and low molecular weight poly (vinyl carbazole) PVKL, doped with iridium, tris(2-phenylpyidine) Ir(ppy)3 as a host-guest emitting layer (EML), shows a dramatic increase in device efficiency. When the PVKH was used as a hole transport electron blocking layer (HT-EBL), effective electron blocking was achieved, which leads to an increase exciton population in the phosphorescent zone. The use of low molecular weight PVKL as a host material in the top layer prevents barrier formation for hole transport from the poly(3,4-ethylenedioxy-thiophene) (PEDOT)–EBL to the EML. External quantum efficiency of 11%, current efficiencies of 38 cd/A, power efficiency of 13 lm/W and brightness of 7000 cd/m2, were obtained. The effect of the PVKH layer on the electrical and optical device characteristics was investigated. Simulation of the optical outcoupling using SETFOS 3.1 software is in agreed with the observed results and allowed us to predict the emissive dipole location and distribution in the EML layer. The effect of the PVKH on the exciton quenching by the electrodes was also investigated using time resolved fluorescence photon counting, which indicates weak exciton quenching by the PEDOT layer and the device enhancement predominantly achieved by exciton confinement in the emissive layer.

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Section: B Device Emission Characteristicssupporting

confidence: 56%

Section: Electrical Characteristics and Device Performancementioning

confidence: 99%

Section: -4mentioning

confidence: 99%

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Solution processed multilayer polymer light-emitting diodes based on different molecular weight host

Al-Attar

Monkman

2011

Journal of Applied Physics

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“…The interface phenomena are thus crucial towards the development, understanding and improvement of organic-based semiconductor electronic device [1][2][3][4][5][6][7][8][9][10][11][12][13][14] applications such as organic light emitting devices (OLEDs) [15][16][17][18], organic photovoltaic devices [19][20][21], organic thin film transistor devices [22][23][24][25][26][27] and organic spin electronic devices in which the transport and control of spin polarized information are represented [28][29][30]. The interface between the different materials that make them up determines the charge transport and charge injection efficiency, with implications for the performance of the devices.…”

Section: Introductionmentioning

confidence: 99%

Effect of Switching on Metal-Organic Interface Adhesion Relevant to Organic Electronic Devices

Babatope¹,

Akogwu²,

Adewoye³

et al. 2013

AMPC

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Considerable efforts are currently being devoted to investigation of metal-organic, organic-organic and organic-inorganic interfaces relevant to organic electronic devices such as organic light emitting diode (OLEDs), organic photovoltaic solar cells, organic field effect transistors (OFETs), organic spintronic devices and organic-based Write Once Read Many times (WORM) memory devices on both rigid and flexible substrates in laboratories around the world. The multilayer structure of these devices makes interfaces between dissimilar materials in contact and plays a prominent role in charge transport and injection efficiency which inevitably affect device performance. This paper presents results of an initial study on how switching between voltage thresholds and chemical surface treatment affects adhesion properties of a metal-organic (Au-PEDOT:PSS) contact interface in a WORM device. Contact and Tapping-mode Atomic Force Microscopy (AFM) gave surface topography, phase imaging and interface adhesion properties in addition to SEM/EDX imaging which showed that surface treatment, switching and surface roughness all appeared to be key factors in increasing interface adhesion with implications for increased device performance.

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“…Since large changes were only seen when there was a change in the SiNx thickness, the microcavity was mainly controlled by the high refractive index SiNx, as well as the transparency of the most reflecting contact. Weak microcavity effects could be responsible for a change in the emission spectra, as previously seen in OLEDs [129][130][131]. The spatial distribution of the field changed since interference effects within the layers were likely to have affected the emission.…”

Section: Optical Field Calculationsmentioning

confidence: 80%

Active channel field-effect transistors: Towards high performance light emitting transistors

Tandy¹

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This thesis describes the study of the development and device physics of organic field-effect transistors and organic light-emitting field-effect transistors. Using chemical and physical properties of organic semiconductors such as light emission, multi-functional devices, or "Active Channel Field-Effect Transistors" can be created. This thesis first describes the creation of basic ambipolar FETs before building on this knowledge to develop ambipolar as well as hole-dominated light emitting field-effect transistors.Ambipolar FETs using a diketopyrrolopyrrole-based copolymer were first investigated in this thesis. When gold electrodes were used, the devices could transport only holes. The charge injection was altered by changing the contacts to aluminium. The devices then were able to conduct both electrons and holes with maximum electron and hole mobilities of order 10 −4 cm 2 V −1 s −1 and 10 −3 cm 2 V −1 s −1 respectively.Light-emitting field-effect transistors were first studied using the model emissive polymerSuper Yellow. Charge injection was studied by altering the electron-injecting contact. Materials used included the low work function metals Ca, Ba and Sm, the inorganic salt Cs 2 CO 3 and the organic material TPBi. Ambipolar devices were created using a neat Super Yellow layer. Electron and hole mobilities in these devices were both of the order of 10 −4 cm 2 V −1 s −1 . The maximum external quantum efficiency was 1.2 ± 0.2 % with a Sm electron-injecting contact, however this occurred at a brightness of less than 1 cd m −2 . A maximum brightness of 43 ± 9 cd m −2 was obtained using a Cs 2 CO 3 -Ag electron-injecting contact in electron accumulation mode. At this brightness, the external quantum efficiency was 0.19 ± 0.04 %.Unipolar devices were also fabricated by adding high mobility charge transport layer of PBTTT underneath the Super Yellow. Since PBTTT had a hole mobility that was orders of magnitude greater than the charge carrier mobilities of Super Yellow, charges were transported in the PBTTT, and recombined within the Super Yellow layer. Super Yellow acted as an emissive layer only. Using this bilayer device architecture, a maximum brightness of 100 ± 4 cd m −2 was obtained with a Ca electron-injecting contact. An external quantum efficiency of 0.04 ± 0.01 % was achieved at the maximum brightness.In order to improve the external quantum efficiency of LEFETs, phosphorescent materials were chosen for use as the emissive layer. A co-evaporated layer of the iridium complex Ir(ppy) 3 in a host of CBP was initially used in the devices. Charge injection was studied by using either a Ba or a TPBi/Ba electron-injecting contact. 4Devices were first fabricated using PBTTT as a hole-dominated charge transport layer.Using a TPBi/Ba electron-injecting contact, the maximum brightness achieved was 200 ± 40 cd m −2with an external quantum efficiency of 0.18 ± 0.01 % at the maximum brightness. Devices were then fabricated using a charge transport layer of DPP-DTT to create ambipolar devices. Electron and ...

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An organic LED display exhibiting pure RGB colors

Cited by 76 publications

References 9 publications

Solution processed multilayer polymer light-emitting diodes based on different molecular weight host

Solution processed multilayer polymer light-emitting diodes based on different molecular weight host

Effect of Switching on Metal-Organic Interface Adhesion Relevant to Organic Electronic Devices

Active channel field-effect transistors: Towards high performance light emitting transistors

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