Ultrasonic Spray-Assisted Solution-Based Vapor-Deposition of Aluminum Tris(8-hydroxyquinoline) Thin Films

Piao, Jinchun; Katori, Shigetaka; Ikenoue, Takumi; Fujita, Shizυo

doi:10.7567/jjap.50.020204

Cited by 9 publications

(7 citation statements)

References 18 publications

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“…The choice of solvent is an initial but critical issue for solution processing technique, because a considerable amount of organic small molecules need to be able to be dissolved into it. Figure a shows the molecular structure of Alq 3 , the common solvents reported in literature for which are chloroform and acetone, which have a high polarity index of 4.1 and 5.1, respectively. However, both of these options have some inevitable technical drawbacks.…”

Section: Resultsmentioning

confidence: 99%

Solution Processing Small‐Molecule Organic Emitter in Field‐Induced, Carrier Gated Lighting Devices

Carroll

et al. 2017

Advanced Optical Materials

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polymers, organic small molecule materials provide more advantages, particularly high stability and a wide selection of emitter materials which span the entire visible spectrum. [17,18] The major drawback of organic small molecule thin film devices is the considerably strict manufacturing requirement on high vacuum evaporation. [19] Therefore, it is necessary to develop an alternating current organic electroluminescent (AC-OEL) device based on soluble organic small molecule emitters.Due to the insulators sandwiching a p-i-n structure, the operating voltage in AC-OEL has to be very high (over 100 V in the most cases) [20,21] this is because of the inefficient carrier transportation in AC cycles which causes a great number of hot carriers that need to be neutralized at insulator/hole generation layer (HGL) interfaces. This in turn leads to irradiative recombination of electron-hole pairs. In this respect, the use of an n-type, wide bandgap semiconducting gate has been demonstrated as a good strategy to manipulate effective carriers and to lower driving voltage, [8,22] which solves the device's overheating issue.Here, tris(8-hydroxyquinolinato)aluminum (Alq 3 ) was chosen as the emitting host material, as it is the most common used emitter in vacuum-deposition. [23,24] The soluble properties of Alq 3 in different organic solvents were studied and the morphological properties of the films using solution process were compared to the evaporated film. The nongated and ZnO-gated AC-OEL devices were also fabricated with solution processed Alq 3 and the electrical and optical responses over driving frequency were further investigated. The analysis of the performance of the AC-OEL devices near DC and at the resonant frequency revealed that carriers are generated under an AC electric field, and at the same time, electrons and holes are efficiently manipulated at the ZnO gate/HGL interface.

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Section: Resultsmentioning

confidence: 99%

Solution Processing Small‐Molecule Organic Emitter in Field‐Induced, Carrier Gated Lighting Devices

Carroll

et al. 2017

Advanced Optical Materials

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“…This means that the optimum substrate temperature is 200 °C under the present values of other deposition conditions (concentration of AlQ 3 , gas flow rate, etc.). The optimum substrate temperature is quite different, that is, higher, compared to that (140–160 °C) for the deposition on glass substrates 10. Referring the model proposed as the deposition process 10, it is considered that the rougher substrate surface of ITO compared to glass obstructed the migration of AlQ 3 sources on the substrate surface.…”

Section: Resultsmentioning

confidence: 99%

“…In our previous study, we demonstrated successful formation of AlQ 3 thin films on glass substrates using a solution‐based vapor deposition method, that is, the ultrasonic‐assisted mist deposition method 10. Efforts were made to prepare a solution of AlQ 3 in methanol, which is cheaper and more environmental‐friendly than tetrahydrofuran or dichloroethane reported in Refs.…”

Section: Introductionmentioning

confidence: 99%

Formation of aluminum tris (8‐hydroxyquinoline) solution in methanol and fabrication of thin films by ultrasonic spray‐assisted vapor deposition

Piao

Katori

Ikenoue

et al. 2012

Physica Status Solidi (a)

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Small molecular material, aluminum tris (8‐hydroxyquinoline) (AlQ3), was found to be soluble in methanol under application of high ultrasonic power, and this has opened safe and environmental‐friendly solution‐based deposition of thin films. The chemical state of AlQ3 was analyzed by nuclear magnetic resonance study and the results showed there was no severe damage on AlQ3 atoms applied by high ultrasonic power. The AlQ3 films were fabricated by ultrasonic‐assisted mist deposition method on indium‐tin‐oxide. The low leakage current suggested well‐defined AlQ3 thin films without significant electrical defects such as pinholes.

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“…For the deposition of organic thin films, we prepare organic solutions of the target material. The mist particles reach above the substrate surface, where the solution is vaporized and the solute remains on the substrate [3]. This mechanism is the vaporized deposition mode similar to spin-coating.…”

Section: Deposition Technologymentioning

confidence: 99%

“…For single-crystalline oxide semiconductors, layer-by-layer growth of ZnO, which has been difficult by MOCVD, was successfully achieved [3]. The electron mobility close to 100 cm 2 /Vs was realized.…”

Section: Single Crystalline Oxidesmentioning

confidence: 99%

Ultrasonic-Assisted Mist Deposition for Green Materials and Devices

Fujita¹,

Kaneko²,

Katori³

et al. 2013

Extended Abstracts of the 2013 International Conference on Solid State Devices and Materials

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Ultrasonic Spray-Assisted Solution-Based Vapor-Deposition of Aluminum Tris(8-hydroxyquinoline) Thin Films

Cited by 9 publications

References 18 publications

Solution Processing Small‐Molecule Organic Emitter in Field‐Induced, Carrier Gated Lighting Devices

Solution Processing Small‐Molecule Organic Emitter in Field‐Induced, Carrier Gated Lighting Devices

Formation of aluminum tris (8‐hydroxyquinoline) solution in methanol and fabrication of thin films by ultrasonic spray‐assisted vapor deposition

Ultrasonic-Assisted Mist Deposition for Green Materials and Devices

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