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Patent Issued for Printable Light-Emitting Compositions

May 28, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- A patent by the inventors Mochizuki, Amane (San Diego, CA); Kondo, Takashi (Settsu, JP); Li, Sheng (Vista, CA); Froehlich, Jesse Dan (Vista, CA); Chae, Hyunsik (San Diego, CA), filed on October 13, 2009, was published online on May 13, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8721922 is assigned to Nitto Denko Corporation (Osaka, JP).

The following quote was obtained by the news editors from the background information supplied by the inventors: "This invention relates to light emitting compositions and light-emitting devices that include the light-emitting compositions. Specifically, this invention relates to light emitting compositions that are printable and light-emitting devices that include iridium-functionalized nanoparticles.

"Organic Light Emitting Diodes (OLEDs) can be composed of small molecule or polymeric fluorescent or phosphorescent compounds. OLEDs comprise a cathode, a hole transporting layer, an emissive layer, an electron transporting layer and an anode. OLED devices emit light as a result of recombination of positive charges (holes) and negative charges (electrons) inside an organic compound (emissive) layer. This organic compound is referred as an electro-fluorescent material or electro-phosphorescent material depending on the nature of the radiative process. As OLED devices have developed to increase luminousity and increased lifetimes, additional layers, such as hole blocking layers and electron blocking layers, have been incorporated into the OLED device. However, introducing more layers of materials has made the OLED structure increasingly complex. This increased complexity makes the fabrication process significantly more difficult. The addition of layers also makes fabrication more difficult because poor control of layer thickness may impair performance. Thus, improving the performance of OLEDs is often tedious, difficult, and expensive.

"There are several methods for manufacturing these above described layers within an OLED device. Primary methodologies include dry processing and wet processing. Dry processing is processing performed without a liquid. Examples of a dry processing operation include dry etching, laser ablation, chemical vapor deposition and vacuum deposition. Dry processing methods have several drawbacks, including difficulty controlling the thickness or composition of a previously deposited layer during serial deposition, high cost of equipment set up and maintenance, slow processing, and difficulty with substrates having a large area. Thus wet production methods may offer significant advantages.

"Solution or wet-processing includes the dissolution or suspension of the precursor materials in a solvent and the application of the solution to the desired substrate. Exemplary methodologies include spin coating and inkjet applications. Spin coating can be undesirable because large quantities of the dissolved solution are spun off of the desired surface during the coating process. Thus, large amounts material is wasted production costs are higher.

"Inkjet fabrication is less expensive. Inkjet fabrication also allows fine patterning in a simple manner and in a short time. Furthermore, it provides better control of luminescent characteristics such as color balance and brightness (luminance) because the thickness of the layer is easily controlled through adjustment of the discharge amount of the ink or by adjusting the ink concentration."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "The inventors have discovered compositions that are, inter alia, useful as ink compositions that may be used in inkjet printers to fabricate light emitting compositions and devices. Some embodiments described herein relate to compositions comprising an iridium-functionalized nanoparticle that can include a nanoparticle core and an iridium-complex. In other embodiments, the iridium-functionalized nanoparticles described herein are light-emitting, e.g., white light-emitting.

"One embodiment disclosed herein is a composition comprising an electron transport compound, an emissive compound, and an organic solvent, wherein the emissive compound is represented by formula (I):

"##STR00001## wherein core is a nanoparticle core, n is 2, X is a single bond or

"##STR00002## each

"##STR00003## is independently a first optionally substituted bidentate ligand;

"##STR00004## is a second optionally substituted bidentate ligand selected from:

"##STR00005## wherein m is an integer in the range of 1 to 9, p is an integer in the range or 1 to 20, z is 0, 1 or 2, R.sup.1 is selected from alkyl, substituted alkyl, aryl and substituted aryl, R.sup.2 is selected from: alkyl, substituted alkyl, aryl and substituted aryl, and * indicates a point of attachment of the second optionally substituted bidentate ligand to the core or X.

"One embodiment also disclosed herein is a composition comprising an electron transport compound, an emissive compound, and an organic solvent, wherein the emissive compound is represented by one of the following formulas:

"##STR00006## wherein R' is represented by

"##STR00007## or

"##STR00008## and R'' is represented by

"##STR00009## wherein each

"##STR00010## is independently a first optionally substituted bidentate ligand, and

"##STR00011## is a second optionally substituted bidentate ligand; R.sup.3 is

"##STR00012## wherein k is 0 or an integer selected from 1 to 20, and R.sup.5 is independently selected from the following:

"##STR00013## ##STR00014## ##STR00015##

"wherein R is independently selected from H or alkyl, and * indicates a point of attachment in R.sup.3.

"Another embodiment provides a method of fabricating a light-emitting device comprising depositing any composition disclosed herein upon an electrically conductive substrate via an inkjet printer.

"Another embodiment provides a composition (IV) comprising: an emissive compound represented by Formula (IV), and an electron transport compound; and an organic solvent.

"##STR00016##

"With respect to Formula (IV), each R.sup.4 is independently selected from:

"##STR00017## and R.sup.5 is

"##STR00018##

"Another embodiment is composition (V) comprising: an emissive compound represented by Formula (V), an electron transport compound, and an organic solvent.

"##STR00019##

"With respect to formula (V), each R.sup.6 is independently selected from the following:

"##STR00020##

"These and other embodiments are described in greater detail below."

URL and more information on this patent, see: Mochizuki, Amane; Kondo, Takashi; Li, Sheng; Froehlich, Jesse Dan; Chae, Hyunsik. Printable Light-Emitting Compositions. U.S. Patent Number 8721922, filed October 13, 2009, and published online on May 13, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=101&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=5011&f=G&l=50&co1=AND&d=PTXT&s1=20140513.PD.&OS=ISD/20140513&RS=ISD/20140513

Keywords for this news article include: Nanoparticle, Nanotechnology, Emerging Technologies, Nitto Denko Corporation.

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Source: Journal of Engineering


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