Investigations on the Aluminum/Para-Hexaphenyl Interface in Light Emitting Devices

1997 ◽  
Vol 488 ◽  
Author(s):  
N. Koch ◽  
L.-M. Yu ◽  
J.-L. Guyaux ◽  
Y. Morciaux ◽  
G. Leising ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Material ◽  
Direct Interaction ◽  
Metal Electrode ◽  
Insulating Layer ◽  
Aluminum Films ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Thin Aluminum

AbstractBlue light emitting devices (LED) with para-hexaphenyl (PHP) as the active material and aluminum as cathode exhibit very high quantum efficiencies. To further optimize device performance it is crucial to understand the physical properties of the involved interfaces. We have performed Rutherford-Backscattering experiments on actual devices to show the importance of oxygen in the interface formation at the cathode as this leads to the formation of a layer of AlxOy between PHP and aluminum. In devices, where the organic film is exposed to air before the metal electrode is evaporated, an insulating layer on the metal-side therefore is inherent. It has been shown that the introduction of an intermediate layer between active material and electrodes results in a higher quantum efficiency of the LED, the most common concepts being charge-transport-layers, or insulators on the other hand. Our results underline the need for a better control of the LED processing. Ultraviolet- and X-ray photoelectron spectroscopy in situ growth studies of thin aluminum films on PHP have been made to reveal the change in the electronic structure of the active medium in a LED in the absence of oxygen. Also the direct interaction of oxygen with this organic material is investigated by photoelectron spectroscopy.

An Arxps Investigation of the Initial Growth of Aluminum Films on the (0001) Face of Sapphire.

1989 ◽  
Vol 153 ◽  
Author(s):  
Mehran Arbab ◽  
Gary S. Chottiner ◽  
R. W. Hoffman
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bulk Composition ◽  
Layer By Layer ◽  
Initial Growth ◽  
Aluminum Films ◽  
Vacuum Interface ◽  
Layer Adsorption ◽  
Thin Aluminum ◽  
Low Energy Electron

AbstractThe (0001) face of α-Al2O3 and the initial growth of ultra-thin aluminum, films deposited on this surface were studied by a combination of low energy electron diffraction, angle resolved x-ray photoelectron spectroscopy and thermal desorption techniques. At high temperatures, the (0001) face of α-Al2O3 reconstructs to form a (√31×√31)R±9° structure which remains stable at lower temperatures, as evidenced by IEED. ARXPS shows that the annealed sanple retains its bulk composition up to the solid-vacuum interface.Thin Al films were deposited on the above surface by in situ evaporation. ARXPS results indicate a uniform growth of the initial monolayer of aluminum. Further growth (<3 A°) deviated fr the layer by layer adsorption mechanism.

Conjugated Polymer Surfaces and Interfaces for Light-Emitting Devices

MRS Bulletin ◽  
1997 ◽  
Vol 22 (6) ◽  
pp. 46-51 ◽  
Author(s):  
W.R. Salaneck ◽  
J.L. Brédas
Keyword(s):  
Conjugated Polymers ◽  
Photoelectron Spectroscopy ◽  
Electronic Materials ◽  
Structural Information ◽  
Molecular Solids ◽  
Chemical Modeling ◽  
Polymer Leds ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Surfaces And Interfaces

Since the discovery of high electrical conductivity in doped polyacetylene in 1977, π-conjugated polymers have emerged as viable semiconducting electronic materials for numerous applications. In the context of polymer electronic devices, one must understand the nature of the polymer surface's electronic structure and the interface with metals. For conjugated polymers, photoelectron spectroscopy—especially in connection with quantum-chemical modeling—provides a maximum amount of both chemical and electronic structural information in one (type of) measurement. Some details of the early stages of interface formation with metals on the surfaces of conjugated polymers and model molecular solids in connection with polymer-based light-emitting devices (LEDs) are outlined. Then a chosen set of issues is summarized in a band structure diagram for a polymer LED, based upon a “clean calcium electrode” on the clean surface of a thin film of poly(p-phenylene vinylene) (PPV). This diagram helps to point out the complexity of the systems involved in polymer LEDs. No such thing as “an ideal metal-on-polymer contact” exists. There is always some chemistry occurring at the interface.

Fabrication of Micro-OLEDs by Room-temperature Curing Nanocontact-print Lithography Using DLC Molds

2012 ◽  
Vol 1511 ◽  
Author(s):  
Ippei Ishikawa ◽  
Keisuke Sakurai ◽  
Shuji Kiyohara ◽  
Taisuke Okuno ◽  
Hideto Tanoue ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Nanoimprint Lithography ◽  
Room Temperature ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Insulating Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Ito Glass

ABSTRACTThe microfabrication technologiesfor organic light-emitting devices (OLEDs) are essential to the fabrication of the next generation of light-emitting devices. The micro-OLEDs fabricated by room-temperature curing nanoimprint lithography (RTC-NIL) using diamond molds have been investigated. However, light emissions from 10 μm-square-dot OLEDs fabricated by the RTC-NIL method have not been uniform. Therefore, we proposed the fabrication of micro-OLEDs by room-temperature curing nanocontact-print lithography (RTC-NCL) using the diamond-like carbon (DLC) mold. The DLC molds used in RTC-NCL were fabricated by an electron cyclotron resonance (ECR) oxygen ion shower with polysiloxane oxide mask in electron beam (EB) lithography technology. The mold patterns are square and rectangle dots which has 10 µm-width, 10 µm-width and50 µm-length, respectively. The height of the patterns is 500 nm. The DLC molds were used to form the insulating layer of polysiloxane in RTC-NCL. We carried out the RTC-NCL process using the DLC mold under the following optimum conditions: 0.1 MPa-pressure for coating DLC mold with polysiloxane film, 2.1 MPa-pressure for transferring polysiloxane from DLC mold pattern to indium tin oxide (ITO) glass substrate. We deposited N, N'-Diphenyl -N, N'-di (m-tolyl)benzidine (TPD) [40 nm-thickness] as hole transport layer / Tris(8-quinolinolato)aluminum (Alq3) [40 nm-thickness] as electron transport layer / Al [200 nm-thickness] as cathode on ITO glass substrateas anode in this order. We succeeded in formation of the insulating layer with square and rectangle dots which has 10 µm-width,10 µm-width and 50 µm-length, and operation of micro-OLEDs by RTC-NIL using DLC molds.

In Situ Inkjet Printing of the Perovskite Single-Crystal Array-Embedded Polydimethylsiloxane Film for Wearable Light-Emitting Devices

2020 ◽  
Vol 12 (19) ◽  
pp. 22157-22162 ◽  
Author(s):  
Zhenkun Gu ◽  
Zhandong Huang ◽  
Xiaotian Hu ◽  
Ying Wang ◽  
Lihong Li ◽  
...  
Keyword(s):  
Single Crystal ◽  
Inkjet Printing ◽  
Light Emitting ◽  
Light Emitting Devices

scholarly journals In situ synthesis of stretchable and highly stable multi-color carbon-dots/polyurethane composite films for light-emitting devices

RSC Advances ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 1281-1286 ◽  
Author(s):  
Fei Lian ◽  
Chuanxi Wang ◽  
Qian Wu ◽  
Minghui Yang ◽  
Zhenyu Wang ◽  
...  
Keyword(s):  
Polymer Films ◽  
Carbon Dots ◽  
Composite Films ◽  
Optoelectronic Devices ◽  
In Situ Synthesis ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Polyurethane Composite

Stretchable, mechanically stable multi-color carbon-dots-based polymer films are in situ fabricated, and showed potential for application in optoelectronic devices.

Heteroepitaxy of GaN on Silicon: In Situ Measurements

2005 ◽  
Vol 483-485 ◽  
pp. 1051-1056
Author(s):  
A. Krost ◽  
Armin Dadgar ◽  
F. Schulze ◽  
R. Clos ◽  
K. Haberland ◽  
...  
Keyword(s):  
Low Cost ◽  
Group Iii Nitrides ◽  
In Situ Monitoring ◽  
Attractive Alternative ◽  
Light Emitting ◽  
Group Iii ◽  
Light Emitting Devices ◽  
Thermal Expansion Coefficients ◽  
Long Time

Due to the lack of GaN wafers, so far, group-III nitrides are mostly grown on sapphire or SiC substrates. Silicon offers an attractive alternative because of its low cost, large wafer area, and physical benefits such as the possibility of chemical etching, lower hardness, good thermal conductivity, and electrical conducting or isolating for light emitting devices or transistor structures, respectively. However, for a long time, a technological breakthrough of GaN-on-silicon has been thought to be impossible because of the cracking problem originating in the huge difference of the thermal expansion coefficients between GaN and silicon which leads to tensile strain and cracking of the layers when cooling down. However, in recent years, several approaches to prevent cracking and wafer bowing have been successfully applied. Nowadays, device-relevant thicknesses of crackfree group-III-nitrides can be grown on silicon. To reach this goal the most important issues were the identification of the physical origin of strains and its engineering by means of in situ monitoring during metalorganic vapor phase epitaxy.

In Situ Nitride Growth Studies by Low Energy Electron Microscopy (LEEM) and Low Energy Electron Diffraction (LEED)

1997 ◽  
Vol 3 (S2) ◽  
pp. 611-612
Author(s):  
E. Bauer ◽  
A. Pavlovska ◽  
I.S.T. Tsong
Keyword(s):  
Low Energy ◽  
Energy Electron ◽  
Ex Situ ◽  
Electron Microscopic ◽  
Insulating Layer ◽  
Light Emitting ◽  
Surface Sensitivity ◽  
Microscopic Studies ◽  
Low Energy Electron

Nitride films play an increasing role in modern electronics, for example silicon nitride as insulating layer in Si-based devices or GaN in blue light emitting diodes and lasers. For this reason they have been the subject of many ex situ electron microscopic studies. A much deeper understanding of the growth of these important materials can be obtained by in situ studies. Although these could be done by SEM, LEEM combined with LEED is much better suited because of its excellent surface sensitivity and diffraction contrast. We have in the past studied the high temperture nitridation of Si(l11) by ammonia (NH3)and the growth of GaN and A1N films on Si(l11) and 6H-SiC(0001) by depositing Ga and Al in the presence of NH3 and will report some of the results of this work for comparison with more recent work using atomic nitrogen instead of NH3.

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