WO2007051888A1

WO2007051888A1 - System of organic points, method of obtaining same and use thereof in the production of nanoscopic devices

Info

Publication number: WO2007051888A1
Application number: PCT/ES2006/070170
Authority: WO
Inventors: Javier MÉNDEZ PÉREZ-CAMARERO; Renaud Caillard; Gonzalo Otero; José Angel MARTÍN-GAGO
Original assignee: Consejo Superior De Investigaciones Científicas
Priority date: 2005-11-07
Filing date: 2006-11-07
Publication date: 2007-05-10
Also published as: ES2274720A1; ES2274720B1

Abstract

The invention relates to a system of organic points, consisting of a substrate including a surface having a network of dislocations with nucleation centres and a network of nanoscopic organic aggregates or points comprising a metal island and a series of organic molecules with semiconductor properties. The invention also relates to the method of obtaining said system. The inventive system or material of organic points can be used to produce nanotechnological devices, such as, for example, optoelectronic devices, organic lasers, CD and DVD players, displays for portable computers, televisions and radios, and is also suitable for use in the dye, ink and paint industries.

Description

TITLE

ORGANIC POINT SYSTEM, ITS PROCESSING PROCEDURE AND ITS APPLICATIONS IN THE DEVELOPMENT OF NANOSCOPIC DEVICES

SECTOR OF THE TECHNIQUE

The technical sectors where it would be located are: nanotechnology, materials science, organic chemistry, optoelectonic devices, organic lasers, laptop screens and dye, dye and paint industries.

STATE OF THE CURRENT TECHNIQUE

Already in 1965 Gordon Moore, co-founder of the American company Intel, manufacturer of microprocessors, observed that the density of transistors of an integrated circuit doubled every year, at that time. This fact, which is called Moore's law (http: // www. Intel. Com / technology / magazine / silicon / moores- law-0405.htm), has become a real requirement for the computer industry and it is believed that it will continue to be fulfilled at least in the next two decades. However, Moore's prediction involves a series of technological difficulties that must be overcome. First, traditional inorganic semiconductors

(silicon, germanium, gallium arsenide) on which current transistors are based, have a minimum size limit below which carrier density is too small. Therefore, it is necessary to look for new materials that replace these inorganic semiconductors when making smaller and smaller transistors. Among new substitute materials for current inorganic semiconductors, organic materials are considered as good candidates. Organic materials begin to be widely used in optoelectronic devices

(computer screens and television monitors, to name them the English term, display) has become popular in the popular language given its important properties of electroluminescence and photoluminescence. Apart from the very popular screens of current TFT monitors

(acronym for English; thin film transistor), based on polymers, and OLEDs (in English, organic light emitting diode; Z. Shen, PE Burrows, V. Bulovic, SR Forrest, and ME Thompson, "Three-color, tunable, organic light-emitting devices ", Science 276 (1997) 2009; JRSheats, H. Antoniadis, M.Hueschen, W. Leonard, J.Miller, R.Mon, D.Roitman, A.Stocking," Organic Electroluminiscent Devices ", Science 273, 884 (1996)) in general, you can give as examples of use of organic materials in current devices the displays of radios (those manufactured by the firm PIONEER), screens of cameras (in development by the main companies in the sector) and lighting devices (under development by PHILIPS and General Electrics). Also, the possibility of obtaining laser properties in organic materials is being investigated [M. McGehee, M.A. Diaz-Garcia, F. Hide, R. Gupta, E. K. Miller, D. Moses, A. J. Heeger; "Semiconjugated Polymer Distributed Feedback Lasers"; Appl. Phys. Lett. 72, 1536-1538 (1998); F. Hide, M.A. Diaz-Garcia, B. J. Schwartz, M. R. Andersson, Q. Pei and A. J. Heeger; "Semiconducting Polymers: A New Class of Solid-State Laser Materials"; Science 273, 1833-1836 (1996)].

If one looks at the successive technological advances and the new features that the materials have to contribute in the near future, organic materials must be considered ["Advanced Semiconductor and Organic Techniques" Hardis Morkog, Ed. Academic Press 2003; "Electronic Processes in Organic Crystals and Polymers" M. Pope and Ch. E. Swenberg, Ed. Oxford University Press 1999]. In fact, its advantages and its potential for use in devices are: the aforementioned possibility of "miniaturization" at nanometer sizes (1 nanometer = 0.000000001 meters), the flexibility of these materials (and, therefore, their resistance to shocks), the ease of processing (it is possible to use simple "printing" techniques), the low cost, and the ability to form ordered structures from their own growth patterns, called "self-assembly" [JV Barth, J. Weckesser, L. Lin , A. Dmitriev and K. Kern, "Supramolecular architectures and nanostructures at metal surfaces", Appl. Phys. A 76, 645 (2003); S. Stepanow, M. Lingenfeider, A. Dmitriev, H. Spillmann, E. Delvigne, N. Lin, X. Deng, C. Cai, JV Barth, and K. Kern, "Steering molecular organization and host-guest interactions using two-dimensional nanoporous coordination systems ", Nature Mat. 3, 229 (2004)]. This last property is considered one of the most appropriate strategies to address nanotechnology, since to couple the nanometric devices to the current ones, the first ones must be extended, either through endless replication processes, or using the properties of "self-organization "of the materials. As an example of materials and devices that make use of self-organizing properties, current optoelectronic devices that are based on multilayers of inorganic semiconductor materials, such as quantum dot lasers [D. Bimberg and N. Ledentsov, "Quantum dots: lasers and amplifiers" J. Phys. Condens. Matter 15 R1063-R1076 (2003)]. These devices, the quantum dot lasers, contain within them an active region consisting of aggregates (dots, spheres, islands, disks, etc.), a generic name to designate any form of aggregate) of semiconductor material with a few hundred nanometers. These quantum dots are grown by taking advantage of the self-organizing properties of the materials. Devices as everyday as CD or DVD readers work thanks to an active region of semiconductor quantum dots III-V.

The appearance of these characteristics of low dimensionality in inorganic semiconductors takes place at much larger dimensions than in other materials. In metals, for example, when the size of a conducting wire

(the section) is reduced below one nanometer (1 nm =

10 ^{~ 9} m), quantized conduction effects appear [JI

Pascual, J. Méndez, J. Gómez-Herrero, A.M. Baró, N. Garcia,

V. Thien Binh, Quantum contact in gold nanostructures by scanning tunneling microscopy, Phys. Rev. Lett. 71 (1993) 1852-1855; J. I. Pascual, J. Méndez, J. Gómez-Herrero, A.M. Baró, N. Garcia, U. Landman, W. D. Luedtke, E. N. Bogachek, H. -P. Cheng, Properties of metallic nanowires: from conductance quantization to localization, Science 267 (1995) 1793-1795]. These effects appear in semiconductors when the section is up to 100 nm [B. J. van Wees, H. H. van Houten, CW. J. Beenakker, J. G. Williamson, L. P. Kouwenhoven, D. van der Marel, CT. Foxon, Quantized conduct of point contacts in a two-dimensional electron gas, Phys. Rev. Lett. 60 (1988) 848-850; GIVES. Wharam, T. J. Thornton, R. Newbury,

M. Pepper, H. Ahmed, J. E. F. Frost, D. G. Hasko, D. C Peacock,

GIVES. Ritchie, G.A. C Jones, One-dimensional transport and the quantization of the ballistic resistance, J. Phys. C 21

(1988) L209-L214]. Also, quantum localization effects have been observed in metallic islands [JT Li, WD Schneider, R. Berndt, and S. Crampin, "Electron confinement to nanoscale Ag islands on Ag (IIl): A quantitative study", Phys. Rev. Lett. 80 (1998) 3332-3335] or in holes metal surfaces [J. Méndez and H. Niehus, "Growth of Chromium on the structured surface of A12O3 / NÍA1 (100)", Appl. Surf. Sci. 142 (1992) 152-158] when these objects have smaller sizes or of the order of 10 nanometers. As an impression of the quantum nature of these nanometric objects, the appearance of new states in the density of states of these materials measured by spectroscopy has been observed, or effects of interference of the electron-free gas with the nano-object walls have been observed. New properties also appear in organic materials when the size is reduced.

As for organic materials, one of the most studied for its photoluminescence properties, self-organized growth, anisotropic conduction, resistance to treatments and ease of handling, are the organic molecules of PTCDA (3,4,9,10 perylene-tetracarboxylic- dianhydride) [S. Forest, "Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques", Chem. Rev. 97, 1793 (1997)]. These molecules, from the perilene group, grow in an orderly manner on various inorganic substrates, such as gold metal surfaces [T. Schmitz-Hübsch, T. Fritz, R. Sellam, R. Staub, and K. Leo, "Epitaxial growth of PTCDA on Au (IIl)", Phys. Rev B 55, 7972 (1997); N. Nicoara, E. Román, JM Gómez-Rodriguez, JA Martin-Gago, and J. Méndez, "Scanning tunneling and photoemission spectroscopies at the PTCDA / Au (lll) interface", Organic Electronics 7, 287-294 (2006) ], silver, copper [Th. Wagner, A. Bannani, C. Bobisch, H. Karacuban, M. Stóhr, M. Gabriel, R. Moller, "Growth of PTCDA crystallites on noble metal surfaces" Organic Electronics 5 (2004) 35-43], and on surfaces semiconductors passivated as GaAs (passivated with sulfur) [N. Nicoara, I. Cerrillo, D. Xueming, JM Garcia, B. Garcia, C. Gómez, J. Mendez, and AM Baró "Preparation and passivation of GaAs (OOl) surfaces for growing organic molecules. "Nanotechnology 13 (2002) 352-356] or hydrogen passivated silicon [Q. Chen, T. Rada, Th. Bitzer, NV Richardson" Growth of PTCDA crystals on H-Si (IIl) surfaces "Surface Science 547 (2003) 385-393] The photodiodes made with these molecules have the highest photoluminescence values obtained in organic materials [S. Forest, "Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques", Chem. Rev. 97 , 1793 (1997)].

Previously, nanostructures of inorganic semiconductor material, commonly referred to as "quantum dots" mentioned above, and metal nanostructures, which have been termed "clusters" or metal aggregates, have already been prepared. More recently, interesting magnetic properties have been obtained in gold metal clusters surrounded by an organic shell [P. Crespo, R. Litrán, TC Rojas, M. Multigner, JM de la Fuente, JC Sánchez-López, MA Garcia, A. Hernando, S. Penadés, and A. Fernández, "Permanent Magnetism, Magnetic Anisotropy, and Hysteresis of Thiol -Capped GoId Nanoparticles ", Phys. Rev. Lett. 93, 087204 (2004); I. Carmeli, G. Leitus, R. Naaman, S. Reich, and Z. Vager, "Magnetism induced by the organization of self-assembled monolayers", J. Chem. Phys. 118, 10372 (2003)].

Hence the interest in developing new materials that include this type of organic compound, especially nanostructures with sizes smaller than 10 nanometers.

DESCRIPTION OF THE INVENTION Brief Description

An object of the present invention is a system of organic points (organic aggregate or compound of metallo-organic coordination), hereinafter referred to as the organic point system of the invention, comprising: a) a substrate with a surface presenting a network of dislocations with nucleation centers, and b) a network of nanoscopic organic points or aggregates consisting of: i) a metal island on the substrate of a), which consists of atoms of a different metal from that of the substrate anchored to the nucleation centers of the substrate, with an ordered network structure of equally spaced islands of similar size, and ii) a series of organic molecules with semiconductor properties, which present photoluminescence and self-organized growth and are fixed as an aggregate to the bi-metallic island).

Another object of the present invention is the method of obtaining the organic point system of the invention, hereinafter method of obtaining the invention, which comprises the following steps: a) formation or selection of a metal substrate with a surface having a network of dislocations with nucleation centers, b) formation by means of a metal evaporator by electronic bombardment under ultra-high vacuum conditions of metallic islands on the previous substrate, at an ambient temperature of less than 50 ° C, preferably between 20 and 35 ^a C , and at a rate of less than one tenth of an angle per minute (0.1 Á / min) for a period of 10 to 30 seconds (up to a coating between 0.01 and 0.02 monolayers), by anchoring atoms of a different metal than the substrate in the substrate nucleation centers, thus creating an orderly network of equally spaced islands of equal size, and c) formation of an organic aggregate network The optically active semiconductors setting over the network of previous islands organic molecules with semiconductor properties, presenting photoluminescence and self-organized growth, by a quartz crucible surrounded with a filament (Figure 1) or using a commercial Knudsen type evaporator, evaporating the organic material at a typical evaporation rate of 0.1 Á / min for 3 minutes (to a coating of 0.1 monolayers).

In addition, the organic point system or material of the invention can be used in the elaboration of nanotechnological devices such as those belonging, by way of illustration and without limiting the scope of the invention, to the following group: optoelectonic devices, organic lasers, readers of CDs and DVDs, laptop screens, TV photo machines, radios, and dye, dye and paint industries [M. McLean, M. Bader, L. Dalton, R. Devine, and W. Steier, "A photophysical and structural study on dye-type organic molecules with potentially useful nonlinear optical properties" J. phys. chem. 94, 4386-4387 (1990)]. Another object of the present invention is an organic dot device, hereinafter the organic dot device of the invention, comprising the organic dot system of the present invention.

Another particular object of the invention is the device of organic points in which said device is a light emitter by electric excitation of organic points comprising: a) a system of organic points of the invention, b) a layer of transparent material formed by organic molecules of naphthalene-tetracarboxylic dianhydride (NTCDA) that covers the organic material of a), and c) a gold coating reconstructed on its surface on the transparent layer of b) of the same characteristics to the previous substrate, which fulfills the mission of electrode, together with the substrate, and that allows to establish an electrical circuit through the transparent layer and the aggregates.

Detailed description

The present invention is based on the fact that the inventors have observed that the formation of nanoscopic organic aggregates is possible (less than 10 nm and even 4 nm; 1 nanometer = 10 ^{~ 9} meters), specifically of organic molecules of PTCDA (acronyms of perylene) -tetracarboxylic dianhydride), spontaneously by self-organization of the materials used, and, more specifically, using metal atoms, for example, iron and cobalt as specific anchor points to a substrate or surface comprising a dislocation network or nucleation points, for example, of reconstructed gold Au (IIl) (Example 1 and 2), and on which the organic aggregates are grown in an orderly manner. By controlling the evaporation time of the materials used (the anchor metal and the organic molecules), the size of the organic aggregates is controlled. The size and order of these aggregates will determine the resulting properties and the possible amplification of the existing properties. The object of the present application consists of a suitable combination of organic and inorganic materials on a substrate so that, spontaneously by self-organization of the materials, it gives rise to organic "aggregates" (organic points) of a few nanometers in size , and, therefore, with special properties due to the small size and for being constituted by organic molecules. To obtain the nanostructure of the organic material, specific self-organization properties on surfaces have been used. Thanks to these properties and looking for the appropriate conditions, it has been able to form "aggregates" of organic molecules on the surface of a substrate.

On the other hand, in the whole process, unlike other methods, the substrate temperature is maintained at room temperature (between 20 and 35 degrees Celsius) which causes the metal-substrate-atom bonds to be more stable. During the evaporations that take place in the manufacturing process of the invention the temperature of the substrate does not reach values that release the metal atoms of the substrate, since the small amounts of iron and cobalt used make the evaporations can be very short and that the substrate barely warms up by evaporator radiation. In addition, in this way it is not necessary to lower the working temperature to freezing temperatures to handle metastable structures that are less stable at room temperature (other authors have fixed organic molecules in the corners of the reconstruction of gold, but using temperatures of 63 Kelvin [ T. Yokohama, S. Yokoyama, T. Kamikado, Y. Okuno and S. Mashiko "Selective assembly on a surface of supramolecular aggregates with controlled size and shape", Nature 413, 619-621 (2001)])), as is the case in other methods in which said materials degrade at room temperature, in addition to making the process more expensive.

Thus, an object of the present invention is a system of organic points (organic aggregate or metallo-organic coordination compound), hereinafter system of organic points of the invention, comprising: a) a substrate with a surface having a surface dislocation network with nucleation centers, and b) a network of nanoscopic organic aggregates or points consisting of: i) a metal island on the substrate of a), consisting of atoms of a different metal than the substrate anchored to the nucleation centers of the substrate, with an ordered network structure of equally spaced islands of equal size, and ii) a series of organic molecules with semiconductor properties, which present photoluminescence and self-organized growth and are fixed as an aggregate to the bi-metallic island). As used in the present invention, the term "nanoscopic organic points or aggregates" refers to an organic aggregate or metallo-organic coordination compound smaller than 10 nm in size and having characteristics with potential applications (optimally active semiconductors).

A particular object of the invention is an organic point system in which the inorganic substrate of a) is a substrate or surface capable of fixing the metal of bl) at specific points, or what is the same a substrate or a surface which has a network of dislocations with equally spaced nucleation zones and belongs to the following group: metals, for example, gold

(on its face (111) it is the only noble metal that presents a reconstruction), or on heteroepitaxy surfaces with a network parameter difference (for example, such as the growth of two silver or copper monolayers on Pt (IIl), where dislocation networks appear due to surface tensions caused by the difference in the size of the atoms of the different materials [H. Bruñe, Surf. Sci. Reports 31, (1998)] and semiconductor materials (as in InAs on GaAs ( IIl) or GaAs (IlO), where dislocation networks are also formed [J. BeIk, J. Sudijono, H. Yamaguchi, X. Zhang, D. Pashley, C. McConville, T. Jones, and B. Joyce, " Scanning tunneling microscopy studies of strain relaxation and misfit dislocations in InAs layers grown on GaAs (IlO) and GaAs (IIl) A "J. Vac. Sci. And Technol.

A 15, 915 (1997); J. BeIk, J. Sudijono, X. Zhang, J. Neave,

T. Jones, and B. Joyce "Surface Contrast in Two Dimensionally Nucleated Misfit Dislocations in InAs

/ GaAs (IlO) Heteroepitaxy ", Phys. Rev. Lett. 78, 475

(1997)]), this heteroepitaxial growth is the foundation of the formation of semiconductor quantum dots mentioned in the state of the art, which constitute the active region of quantum dot lasers.

A particular embodiment of the invention is the organic dot system of the invention in which the metallic substrate of a) is a reconstructed gold surface, Au (IIl) that has reconstruction 22V3. Another particular embodiment of the invention is the organic dot system of the invention in which the metallic substrate of a) is a gold surface evaporated on a mica or quartz substrate [M. Hegner, P. Wagner, and G. Semenza, "Ultralarge atomically fíat template-stripped Au surfaces for scanning tunneling microscopy", Surface Science 291, 39 (1993)].

Another particular object of the invention is the organic point system of the invention in which the metal islands are constituted by metal atoms belonging to the following group: iron, cobalt and nickel.

Another particular embodiment of the invention is the organic point system of the invention in which the metal islands of bi) are constituted by iron atoms (Figure 2). Another particular embodiment of the invention is the organic point system of the invention in which the metal islands of bi) are constituted by cobalt atoms (Figure 3). Another particular object of the invention is the organic point system of the invention in which the organic molecule of b.ii) is an organic molecule belonging to the following group: molecules of the perilene family (for example, PTCDA (3, 4,9,10 perylene-tetracarboxylic dianhydride), NTCDA (naphthalene tetracarboxylic dianhydride), Di-Me-PTCDI (N, N ^f- dimethyl-3, 4, 9, 10-perylene-tetracarboxylic-diimide) and perylene ) or thialocyanines (eg, CuPc (copper thialocyanine), MPc).

Another particular embodiment of the invention is the organic dot system of the invention in which the organic molecule of b.ii) is organic molecules of PTCDA (3,4,9,10 perylene-tetracarboxylic dianhydride) (Figures 4 and 5) .

Another more particular embodiment of the invention is the organic point system of the invention in which the metal islands of bi) are constituted by iron or cobalt atoms and in which the organic molecule of b.ii) are organic molecules of PTCDA (3,4,9,10 perylene tetracarboxylic dianhydride) (Figures 4 and 5).

Another object of the present invention is the method of obtaining the organic point system of the invention, hereinafter method of obtaining the invention, which comprises the following steps: a) formation or selection of a metal substrate with a surface having a network of dislocations with nucleation centers, b) formation by means of a metal evaporator by electronic bombardment under ultra-high vacuum conditions of metallic islands on the previous substrate, preferably at room temperature, between 20 and 35 ^at C, and at a lower speed at one tenth of an angle per minute (0.1 Á / min) for a period of 10 to 30 seconds (up to coating between 0.01 and 0.02 monolayers), by anchoring atoms of a different metal to that of the substrate in the nucleation centers of the substrate, thus creating an orderly network of equally spaced islands of equal size, and c) forming a network of organic aggregates Optically active semiconductors fixing organic molecules with semiconductor properties on the previous island network, presenting photoluminescence and self-organized growth, by means of a quartz crucible surrounded with a filament (Figure 1) or using a commercial Knudsen evaporator, evaporating the organic material to a typical evaporation rate of 0.1 Á / min for 3 minutes (to a coating of 0.1 monolayers).

The use of a metal evaporator by electronic bombardment [J. Nelly, "Electron bombardment apparatus for vacuum evaporation" J. Sci. Instrum. 36, 89-90 (1959)] of b) is a widely known technique in the field of ultrahigh vacuum techniques.

Another particular object of the invention is the process of the invention in which the inorganic substrate of a) is a substrate or surface capable of fixing the metal of bl) or what is the same surfaces that present a network of dislocations with zones of equiespaced nucleation, belonging to the following group: metals, for example gold, or with heteroepitaxy surfaces with a network parameter difference (silver or copper on platinum) or semiconductors (for example InAs on GaAs). In the case of semiconductor materials, this heteroepitaxial growth is the foundation of the formation of the semiconductor quantum dots mentioned above, which constitute the active region of quantum dot lasers.

Another particular embodiment of the invention is the process of the invention in which the a) metallic substrate is a reconstructed gold surface, Au (IIl) that presents the 22V3 reconstruction or an evaporated gold surface on a mica or quartz substrate. Another particular object of the invention is the process of the invention in which the metal islands are constituted by a metal atom belonging to the following group: iron, cobalt and nickel.

Another particular embodiment of the invention is the process of the invention in which the metal islands of bi) are constituted by iron atoms evaporated by electronic bombardment under ultra-high vacuum conditions at a rate of less than one tenth of an angle per minute ( 0.1 Á / min) for 10-30 seconds, the iron islands forming spontaneously at the corners of the reconstruction and these islands corresponding to a coating of less than 0.01 monolayers (ML) (data not shown), similar to Figure 2 , but with a smaller coating (Figure 2 corresponds to 0.08 monolayers).

Another particular embodiment of the invention is the process of the invention in which the metal islands of bi) are constituted by cobalt atoms evaporated by electronic bombardment under ultra-high vacuum conditions and at a rate of less than one tenth of an angle per minute ( 0.1 Á / min) for 10-30 seconds, the cobalt islands forming spontaneously at the corners of the reconstruction and these islands corresponding to a coating less than 0.01 monolayers (ML) (data not shown), similar to Figure 3 , but with a smaller coating (Figure 3 corresponds to 0.08 monolayers). Another particular object of the invention is the process of the invention in which the organic molecule of b.ii) belongs to the following group: organic molecules of the perilene group (PTCDA (3,4,9,10 perylene-tetracarboxylic) dianhydride), NTCDA (naphthalene-tetracarboxylic-dianhydride), Di-Me-PTCDI (N, N ^f- dimethyl- 3, 4, 9, 10-perylene-tetracarboxylic-diimide), or thialocyanines (e.g., CuPc, MPc).

Another particular embodiment of the invention is the process of the invention in which the organic molecule of b.ii) is organic molecules of PTCDA

(3,4,9,10 perylene-tetracarboxylic dianhydride), which are deposited on the metal islands, after evaporation of the

PTCDA at a speed lower than half an angle per minute (0.5 Á / min), ensuring that the substrate temperature is ambient, between 20 and 35 ° C, preferably between 20 and 35 ^at C, and avoiding having to heat or cool the substrate, the size of the organic aggregates being between 2 nm and 10 nm, depending on the amount of molecules that evaporate on the substrate (Figures s 4 and 5).

As previously mentioned, the organic point system or material of the invention can be used in the elaboration of nanotechnological devices such as those belonging, by way of illustration and without limiting the scope of the invention, to the following group: optoelectonic devices, organic lasers , CD and DVD readers, laptop screens, TV photo machines, radios, and dye, dye and paint industries [M. McLean, M. Bader, L. Dalton, R. Devine, and W. Steier, "A photophysical and structural study on dye-type organic molecules with potentially useful nonlinear optical properties" J. phys. chem. 94, 4386-4387 (1990)]. Another object of the present invention is an organic dot device, hereinafter the organic dot device of the invention, comprising the organic dot system of the present invention. Another particular object of the invention is the device of organic points in which said device is a light emitter by electric excitation of organic points comprising: a) a system of organic points of the invention, b) a layer of transparent material formed by organic molecules of naphthalene-tetracarboxylic dianhydride (NTCDA) that covers the organic material of a), and c) a gold coating reconstructed on its surface on the transparent layer of b) of the same characteristics to the previous substrate, which fulfills the mission of electrode, together with the substrate, and that allows to establish an electrical circuit through the transparent layer and the aggregates.

When a potential difference is established between the two electrodes of c), said current causes an excitation of the organic material and, therefore, the emission of light in the aggregates.

Another particular object of the invention is a light emitting device by electric excitation of organic multilayer points in which the device comprises more than one layer of organic aggregates, each layer being always covered by its corresponding transparent layer, achieving this stacking of layers that the device can emit light with greater intensity. Another particular object of the invention is the organic point device in which said device is a light sensor comprising: a) an organic point system of the invention, b) a layer of transparent material formed by organic molecules of naphthalene-tetracarboxylic-dianhydride (NTCDA) covering the organic material of a), and c) a gold coating reconstructed on its surface on the transparent layer of b) of equal characteristics to previous substrate, that fulfills the mission of electrode, together with the substrate, and that allows to establish an electrical circuit through the transparent layer and the aggregates.

When the external light penetrates to the organic points of the previous device, a potential difference between both electrodes, electrical voltage, can be generated as light sensors.

Another particular object of the invention is a light sensing device in which the device comprises more than one layer of organic aggregates, each layer being always covered by its corresponding transparent layer, this layer stack making the sensor more sensitive against to external light.

Another particular embodiment of the invention is the device of the invention, be it emitter or light sensor, in which the organic material is constituted by: a reconstructed gold substrate, Au (IIl), which has reconstruction 22V3, on on the previous substrate there are iron islands with a coating of less than 0.01 monolayers (ML), formed in the corners of the reconstruction, and on each of the iron islands, optically active semiconductor organic aggregates are formed of organic molecules of PTCDA (3, 4, 9, 10 perylene-tetracarboxylic-dianhydride).

Another particular object of the invention is the method of obtaining the organic point device of the invention comprising the following steps: a) the organic point system of the invention is covered with a layer of transparent material, and b) is deposited by evaporation of a metallic element (metallic coating), to obtain a surface equal to that existing in the substrate of a), the base substrate and the metallic coating acting as electrodes when a potential difference is established between them.

Another particular embodiment of the invention is the method of obtaining the device of organic points of the invention in which after the formation of the layer of transparent material a metallic element is deposited by evaporation, to obtain a surface equal to that of the substrate of starting, and the method of obtaining the organic point system of the invention is repeated several times, ending each cycle always with the layer of transparent material and on it the metallic coating. In this case the base substrate and the last coating of the multilayer stacking act as electrodes when a potential difference is established between them, establishing an electric current inside the transparent layers, by the organic aggregates and by the metal islands, current that excites the organic material of all layers and produces light.

Finally, it should be noted that the metal substrates of the devices of the invention can be so thin that they allow light to pass through them, the light generated in the organic points being able to go outside and the outside light reaching the organic points much more easily. DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1.- Photograph of the molecule evaporator. aa) Thermocouple type K. ab) Opening, ac) Tantalum ring, ad) Tungsten filament, ae) Quartz crucible. Figure 2.- Image of tunnel effect microscopy (STM) of a gold surface Au (IIl) with self-organized iron islands forming islands in the corners of the substrate reconstruction. Image size 70 nm x 36 nm. The iron coating is 0.08 monolayers (ML). Figure 3.- Image of tunnel effect microscopy (STM) of a gold surface Au (IIl) with self-organized cobalt islands forming islands in the corners of the substrate reconstruction. Image size 54 nm X 54 nm. The cobalt coating is 0.08 monolayers (ML). Figure 4.- STM image of an Au (IIl) gold surface with iron islands and PTCDA molecules grown around the iron. These islands of organic molecules constitute each of the organic points. Image size 40 nm X 40 nm. The iron coating is less than 0.01 monolayers (ML) while the molecule coating is 0.1 monolayers (ML).

Figure 5.- STM image of an Au (IIl) gold surface with cobalt islands and PTCDA molecules attached to the cobalt islands. The islands of organic molecules constitute each of the organic points. Image size 41 nm X 41 nm. The cobalt coating is 0.03 monolayers (ML) while the molecule coating is 0.12 monolayers (ML). Figure 6.- Scheme of a prototype of an organic point device, a) Gold surface with organic points, b) After covering the organic points with a transparent organic layer and on this a metallic coating (device) . c) Multilayers of organic dots on metal substrates (multilayer device).

EXAMPLE OF EMBODIMENT OF THE INVENTION Example 1.- Preparation of organic PTCDA molecules of the invention

1.1.- Organic molecules of the invention of iron and PTCDA on gold substrate.

In a first step of the process of the invention, iron islands of a few atoms (much smaller than those shown in Figure 2) were used to form the organic points on a nanostructured surface of Fe / Au (lll). Small amounts of iron, in an amount close to one hundredth of monolayer (0.01 ML), (in figure 2 the result of evaporating 0.08 ML is shown since the effect of evaporating 0.01 ML is less graphically appreciable), they evaporated on the face (111) of a gold monocrystal, Au (IIl), which presents the reconstruction

(22xv3), preferably, a single crystal of Au (IIl), produced the spontaneous formation of iron islands on the corners of the gold reconstruction [B. Voigtlánder et al. "Epitaxial growth of Fe on Au (IIl): a scanning tunneling investigation", Surf. Sci. 255, L529 (1991); H. Bruñe, Surf. Sci. Reports 31, 121 (1998)] as shown in Figure 2 for a larger coating. The iron atoms deposited on the surface of gold diffuse on the substrate until the minimum energy levels of the reconstruction corners (22 * V3) of gold are found. These points act as nucleation centers of the iron islands giving rise to a network of iron islands distributed over the surface. Likewise, the gold surface that presents the reconstruction (22XΛ / 3) to be used may be gold evaporated on a mica or quartz substrate. The evaporation of iron was carried out using an iron evaporator by electronic bombardment [Doctoral thesis of José Abad, CSIC, Autonomous University of Madrid

2005], with a speed typically less than one tenth of an angle per minute (0.1 Á / min).

STM microscopy clearly shows (Figure 2) how iron islands formed at specific points of the gold substrate have formed. The iron islands are the brightest objects in the image. The clear lines that cross the image in "zigzag" are the folds due to the reconstruction of the gold substrate, Au (IIl). The image shows how the iron islands are located at the corners of the gold reconstruction folds.

These iron islands of regular forms, have very regular sizes depending on the amount of iron that evaporates and are also separated by very regular distances forming an orderly network of equiespaced iron islands.

Subsequently, in the present procedure the iron islands were combined with organic molecules of PTCDA. Thus, on this substrate, using a smaller iron coating, organic PTCDA molecules were evaporated on top, the iron atoms acting as seeds around which the organic PTCDA molecules are fixed. In this case, from a quartz crucible surrounded with a filament as shown in Figure 1. The typical evaporation temperature of the PTCDA is around two hundred fifty-five degrees Celsius (255 ° C). The evaporation rate used was less than half an angstrom per minute (0.5 Á / min) tenth of an angstrom per minute (0.1 Á / min), for 3 minutes (up to a coating of 0.1 monolayers). PTCDA molecules will spontaneously reorder around the iron islands, resulting in islands of organic material with an iron seed in their inside. Throughout the process, unlike other methods, the substrate temperature was maintained at room temperature, between 20 ° C and 35 ° C, it being unnecessary to heat or cool the substrate at any time. If the temperature of the substrate exceeds one hundred degrees Celsius (100 °), the iron ceases to be anchored to the corners of the reconstruction of gold and diffuses towards the gold steps, losing its role of fixing the molecules. The substrate temperature does not reach these values in the process of the invention during evaporations, since the small amounts of metal atoms used (coatings much lower than the monolayer) make evaporations very short

(evaporation times of a few minutes) and that the substrate barely warms up by evaporator radiation (the sample temperature does not exceed 50 ° C).

Once the first organic molecules are fixed, other molecules are fixed to the first, giving rise to an organic aggregate that grows while evaporation lasts. These organic aggregates are what have been called "organic points" (see Figure 4). The size of these organic points is determined by the amount of molecules that have evaporated on the surface, obtaining points of sizes between 2 nm and 10 nm in diameter depending on this parameter. The STM image in Figure 4 shows four organic points of PTCDA, about 4 nanometers in average diameter, consisting of between 20 and 35 molecules each. The molecules are the small bright ovals that constitute the aggregates. These aggregates are located in the corners of the folds of the reconstruction of the substrate where there is an iron seed. The iron core, of a few tens of atoms, it can be seen as a brighter central zone than the surrounding molecules.

1.2.- Organic molecules of the invention of cobalt and PTCDA on gold substrate

Previously, the formation of Cobalt and Nickel Islands on the reconstruction of gold has been described [S. Padovani, I. Chado, F. J. P. Bucher, "Transition from zero-dimensional superparamagnetism to two-dimensional ferromagnetism of Co clusters on Au (IIl)". Phys. Rev. B 59, 11887-11891 (1999); D. Chambliss, R. Wilson, and S. Chiang, "Nucleation of ordered Ni island arrays on Au (IIl) by surface-lattice dislocations" Phys. Rev. Lett. 66, 1721-1724 (1991); W. Cullen, and P. First, "Island shapes and intermixing for submonolayer nickel on Au (IIl)" Surf. Sci. 420, 53-64 (1999)].

A Cobalt evaporator has been used, with parameters very similar to those described in example 1.1., Verifying that similar organic aggregates are obtained. Figure 3 shows the result of evaporating 0.08 cobalt monolayers (ML) on the gold surface. Cobalt forms islands in the corners of the reconstruction of gold in a similar way to iron. If a smaller amount of cobalt is deposited (0.03 ML monolayers) and PTCDA molecules are evaporated on top, a growth of organic aggregates attached to the cobalt islands is obtained, as shown in Figure 5.

Example 2.- Use of the organic material of the invention for the elaboration of an organic knitting device.

There are many applications of the invention organic point system that could be cited. As an example and for its actuality, a device similar to semiconductor quantum dot lasers can be mentioned which is called "organic point device". This device, again in analogy with semiconductor quantum dots, could be an "organic dot laser" or an "organic dot sensor." The proposed device is constituted in its active region by multilayers of organic points. In this active region, the organic material is nanostructured forming points of nanoscopic size. The procedure for carrying out these devices is shown in Figure 6. In the first phase, the organic point system of the invention, and in a manner similar to that performed in other PTCDA-based patents [SR Forest et al. "Organic optoelectronic devices and methods" United States Patent # 5315129 (1994)], is covered with a layer of a transparent material such as organic naphthalene-tetracarboxylic-dianhydride (NTCDA) molecules, and the first prototype of the device is obtained, as shown in Figure 6b. Then, on the transparent layer, a reconstructed gold coating on its surface is deposited by evaporation, of equal characteristics to the Au (IIl) substrate, which fulfills the electrode mission, together with the substrate, to establish an electrical circuit through the transparent and aggregates layer, when a potential difference is established between the two electrodes, said current causing light emission in the aggregates.

If you want to obtain a device with multilayers after the formation by evaporation of gold, organic PTCDA points are re-formed on its surface, repeating this process as many times as necessary to result in a multilayer of organic points. In this process, the organic points will be aligned vertically, just as with semiconductor quantum points [Ch. Teichert, "Self-organization of nanostructures in semiconductor heteroepitaxy ", Phys. Rep.

365, 335 (2002)] improving device properties

(better background signal in a laser or greater independence of the direction of incidence in a sensor ["Advanced Semiconductor and Organic Techniques" Hardis Morkog, Ed.

Academic Press 2003; "Electronic Processes in Organic

Crystals and Polymers "M. Pope and Ch. E. Swenberg, Ed.

Oxford University Press 1999]. As a result of the growth of multilayers of organic dots there is the second type of device shown in Figure 6c. The base substrate and the last layer of gold act as metallic contacts of the device. To these metallic contacts the electrical connections are made. In the case of a laser device of organic points, applying voltage to said contacts, light emission from the organic points is obtained. In the case of a sensor device, the light produces a potential difference that is measured between the contacts. The different layers of gold can be made so thin that they allow light to pass through the device. By exchanging gold for a combination of two semiconductor materials of different network parameters, a similar device with different properties can be available. Finally, if other organic materials are used as separators, a flexible and cheap organic dot device is obtained.

Claims

1.- Organic point system characterized in that it comprises: a) an inorganic substrate with a surface that has a network of dislocations with nucleation centers,

And b) a network of nanoscopic organic points or aggregates consisting of: i) a metal island on the substrate of a), consisting of atoms of a different metal than the substrate anchored to the nucleation centers of the substrate, with a network structure ordinate of equispaced islands and of similar size, and ii) a series of organic molecules with semiconductor properties, which present photoluminescence and self-organized growth and that are fixed as an aggregate to the bi-metallic island).

2. Organic points system according to claim 1 characterized in that the inorganic substrate of a) is a substrate or surface capable of fixing the metal of bl) at specific points, or what is the same a substrate or a surface that has a dislocation network with equiespaced nucleation zones and belonging to the following group: metals, for example, gold, or on heteroepitaxy surfaces with a network parameter difference (for example, silver or copper monolayers on Pt (IIl) and semiconductor materials (for example, InAs on GaAs (IIl) or GaAs (IlO).

3. Organic point system according to claim 1, characterized in that the metallic substrate of a) is a reconstructed gold surface, Au (IIl), which has reconstruction 22V3.

4. Organic points system according to claim 1 characterized in that the metallic substrate of a) is a surface of gold evaporated on a substrate of mica or quartz. 5. Organic points system according to claim 1, characterized in that the metal islands of b.l) are constituted by atoms of a metal belonging to the following group: iron, cobalt and nickel.

5. Organic points system according to claim 1 characterized in that the metal islands of b.i) are constituted by iron atoms.

6. Organic points system according to claim 1, characterized in that the metallic islands of b.i) are made up of cobalt atoms.

7. Organic point system according to claim 1 characterized in that the organic molecule of b.ii) is an organic molecule belonging to the following group: molecules of the perilene family (for example, PTCDA

(3,4,9,10 perylene-tetracarboxylic-dianhydride), NTCDA (naphthalene-tetracarboxylic-dianhydride), Di-Me-PTCDI (N, N'-dimethyl-3, 4, 9, 10-perylene-tetracarboxylic-diimide ) and perylene) or thialocyanines (eg, CuPc, MPc).

8. Organic point system according to claim 1 characterized in that the organic molecule of b.ii) are organic molecules of PTCDA (3,4,9,10 perylene tetracarboxylic dianhydride).

9. Organic point system according to claim 1 characterized in that the metal islands of bi) are constituted by iron or cobalt atoms and in which the organic molecule of b.ii) are organic molecules of PTCDA (3,4,9 , 10 perylene-tetracarboxylic dianhydride).

10. Method of obtaining the organic point system according to claims 1 to 9, characterized in that it comprises the following steps: a) formation or selection of a substrate with a surface presenting a network of dislocations with nucleation centers, b) formation by means of a metal evaporator by electronic bombardment under ultra-high vacuum conditions of metal islands on the previous substrate, at room temperature less than 50 ° C, preferably between 20 and 35 ^a C, and at a rate of less than one tenth of an angle per minute (0.1 Á / min) for a period of 10 to 30 seconds (up to a coating between 0.01 and 0.02 monolayers), by anchoring atoms of a different metal to that of the substrate in the nucleation centers of the substrate, and c) formation by evaporation of a network of optically active semiconductor organic aggregates on the network of deb metal islands) with semiconductor properties, which have photoluminescence and self-organized growth, at a typical evaporation rate of 0.1 Á / min for 3 minutes (to a coating of 0.1 monolayers).

11. Method of obtaining the organic point system according to claim 10 characterized in that the formation by evaporation of c) is carried out by a quartz crucible surrounded with a filament or using a Knudsen type evaporator.

12. Method of obtaining the organic point system according to claim 10 characterized in that the inorganic substrate of a) is a substrate or surface capable of fixing the metal of bl) or what is the same surfaces that have a network of dislocations with Equispaced nucleation zones, belonging to the following group: metals, for example gold, or with heteroepitaxy surfaces with a network parameter difference (silver or copper on platinum) or semiconductors (for example, InAs on GaAs).

13. Method of obtaining the organic point system according to claim 10 characterized in that the substrate a) metallic is a reconstructed gold surface, Au (IIl) that presents the reconstruction or an evaporated gold surface on a mica or quartz substrate.

14. Method of obtaining the organic point system according to claim 10 characterized in that the metal islands are constituted by a metal atom belonging to the following group: iron, cobalt and nickel.

15. Method of obtaining the organic point system according to claim 10, characterized in that the metal islands of bi) are constituted by iron atoms evaporated by electronic bombardment under ultra-high vacuum conditions at a rate of less than one tenth of an angle per minute. (0.1 Á / min) for 10-30 seconds, the iron islands forming spontaneously in the corners of the reconstruction and these islands corresponding to a coating less than 0.01 monolayers (ML), but with a smaller coating.

16. Method of obtaining the organic point system according to claim 10, characterized in that the metal islands of bi) are constituted by cobalt atoms evaporated by electronic bombardment under ultra-high vacuum conditions and at a rate of less than one tenth of angstrom per minute. (0.1 Á / min) for 10-30 seconds, the cobalt islands forming spontaneously at the corners of the reconstruction and these islands corresponding to a coating smaller than 0.01 monolayers (ML), but with a smaller coating.

17. Method of obtaining the organic point system according to claim 10 characterized in that the organic molecule of b.ii) belongs to the following group: organic molecules of the perilene group (PTCDA (3,4,9,10 perylene-tetracarboxylic) -dianhydride), NTCDA (naphthalene-tetracarboxylic-dianhydride), Di-Me-PTCDI (N, N ^f- dimethyl- 3, 4, 9, 10-perylene-tetracarboxylic-diimide), or of the thialocyanines (for example, CuPc, MPc).

18. Method of obtaining the organic point system according to claim 10 characterized in that the organic molecule of b.ii) are organic molecules of PTCDA (3,4,9,10 perylene-tetracarboxylic-dianhydride), which are depopulated on the metal islands, after evaporation of the PTCDA at a speed lower than half an angle per minute (0.5 Á / min), achieving that the temperature of the substrate is the environment, below 50 ° C, preferably between 20 and 35 ^a C.

19. Use of the organic point system according to claims 1 to 9 in the elaboration of nanotechnological devices such as those belonging to the following group: optoelectonic devices, organic lasers, CD and DVD readers, laptop screens, photo machines TV , radios, and dye, dye and paint industries.

20.- Organic points device characterized in that it comprises the organic points system according to claims 1 to 9.

21. Device of organic points according to claim 20 characterized in that it is a light emitter by electric excitation of organic points and in that it comprises: a) a system of organic points according to claims 1 to 9, b) a layer of transparent material formed by organic molecules of naphthalene-tetracarboxylic-dianhydride (NTCDA) that covers the organic material of a), and c) a gold coating reconstructed on its surface on the transparent layer of b) of the same characteristics to the previous substrate, which fulfills the mission electrode, together with the substrate, and that allows to establish a circuit electrical through the transparent layer and aggregates.

22.- Organic point device according to claim 21, characterized in that it is a multilayer organic point light emitter in which the device comprises more than one layer of organic aggregates, each layer being always covered by its corresponding transparent layer.

23.- Organic point device according to claim 20 characterized in that it is a light sensor and in that it comprises: a) an organic point system according to claims 1 to 9, b) a layer of transparent material formed by organic naphthalene molecules -tetracarboxylic-dianhydride (NTCDA) covering the organic material of a), and c) a gold coating reconstructed on its surface on the transparent layer of b) of the same characteristics to the previous substrate, which fulfills the electrode mission, together with the substrate, and that allows to establish an electrical circuit through the transparent layer and the aggregates.

24.- Organic point device according to claim 23, characterized in that it is a multilayer organic point light sensor, each layer being always covered by its corresponding transparent layer.

25.- Device of organic points according to claim 20 characterized in that the organic part is constituted by: a) a reconstructed gold substrate, Au (IIl), which has reconstruction 22V3, b) iron islands of a smaller coating of 0.01 monolayers (ML), formed on the corners of reconstruction 22V3 of a), and c) optically active semiconductor organic aggregates of organic molecules of PTCDA (3, 4, 9, 10 perylene-tetracarboxylic-dianhydride) on the islands of b).

26.- Method of obtaining the device of organic points according to claims 20 to 25 characterized in that it comprises the following steps: a) the organic point system of the invention is covered with a layer of transparent material, and b) is deposited by evaporation a metallic element

(metallic coating), to obtain a surface equal to that existing in the substrate of a), the base substrate and the metallic coating acting as electrodes when a potential difference is established between them.

27.- Method of obtaining the device of organic points according to claim 26 characterized in that after the formation of the layer of transparent material a metallic element is deposited by evaporation, to obtain a surface equal to that of the starting substrate, and several are repeated Sometimes the method of obtaining the organic point system of the invention, ending each cycle always with the layer of transparent material and on it the metallic coating.