TW200835015A - A self-assembled monolayer for tuning the work function of metal electrodes - Google Patents

Abstract

The present invention discloses self-assembled monolayers with a general formula G1-R-G2, wherein G1 is SH. R of the mentioned general formula comprises one selected from the group consisting of the following: linear, branched, or cyclic alkyl moiety; linear, branched, or cyclic alkyl moiety including one or more than one substituted moiety selected from the group consisting of alkene, alkyne, halide moiety, alkoxy, siloxy, ketone, alcohol, thioether, carbamate or amino moiety; aromatic group; heterocyclic group; multiple fused ring group; and, multiple fused ring group with heteroatoms. G2 is an electron-withdrawing group.

Description

200835015 IX. Description of the Invention: [Technical Field] The present invention relates to a self-assembled monolayer film, and more particularly to a self-assembled monolayer film which can be used to adjust the work function of a metal electrode. [Prior Art] Display technology has been widely used as a platform for human-machine communication and information display in various fields such as industrial and commercial, military, transportation, medical, education, and entertainment. Over the past half century, the continuous investment in science and engineering research has developed many types of display technologies. Among them, Organic Electroluminescence (0EL) technology has the opportunity to become the next one due to its superior performance and low production cost. The most promising display and illumination source for a generation. Generally, OEL components have the properties of a diode, which can be classified into a small molecule organic light emitting diode (OLED) and a polymer organic light emitting diode η (Polymer) depending on the material of the light emitting layer. Light-Emitting Diode; PLED). The development of 〇LED technology is from Tang and of the Eastman Kodak Company.

In 1987, Vanslyke successfully used thermal evaporation to produce OLED components with high quantum efficiency and low driving voltage. The unique properties of OLEDs are that they illuminate when current is passed through, and the color of the light depends on the structure of the organic molecules. Different molecular structures can produce red, green or blue light respectively, and the RGB elements required for full color display are obtained as of 200835015. The OLED illuminating element has the advantages of self-illumination, south contrast, fast response, light weight, low power consumption, flexibility and wide viewing angle, and its applicable range includes flat or curved display of various electronic and electrical products, various types of signs, Indications, commercial lighting such as signboards, general indoor lighting, and functional large-area lighting have become hot topics of research. The working principle of OLED is based on electroluminescence (Electroluminescence). When an excitatory pair of positively and negatively charged carriers are combined to form an exciton, the energy of the exciton is ultimately in the form of a photon (phot〇n). It is released to generate light; among them, the above-mentioned carrier is called a hole and the negative is called an eiectron. Referring to the first figure, it is a schematic diagram of a common OLED element structure. The most basic LED device comprises a cathode 110, an anode 150 and an emissive layer 130. The electrode and the organic light-emitting layer may further include a hole injection layer. A layer 140 and an electron transport layer 120 facilitate the operation of the OLED. The OLED member may further include a transparent substrate 16A, and each of the OLED elements is constructed on the transparent substrate 160. Referring to the first figure, the arrow indicates the direction of illumination of the above OLED. When an OLED is applied with a forward bias voltage, an electric field is formed inside the element, and under the action of the electric field, electrons and the cathode and the anode are injected into the organic material and migrate to the above-mentioned light-emitting layer. The electrons and the holes meet in the luminescent layer and generate excitons. The excitons transfer energy to the luminescent material molecules under the action of the private field and cause the electrons to transition to the excited state. Finally, the excited electrons release the energy in the form of photons. And return to the ground state to complete the electrical excitation light. Since the OLED emits light by the radiation bonding process of the carrier, the efficiency of the interception generated by the % electrode and injected into the organic material affects the luminous efficiency of the element. At the same time, the rate of positive load sub-injection needs to be balanced as much as possible, otherwise it will not only reduce the combination ratio of the carrier, but also generate a through current in the organic layer to generate heat and thus shorten the life of the component material. When the carrier is injected into the organic material by the electrode, it is necessary to overcome an energy barrier, and for the hole, a, the energy barrier is the work function of the anode electrode and the most two filled track regions of the organic material contacted by the anode electrode. (Lowest Unoccupied Molecular

The energy difference between Orbital; LUMO), and for electrons, the required energy gap is the lowest unfilled domain of the organic material in contact with the cathode electrode (Highest 〇) The energy level difference between ccupied M〇lecular 〇rbital; HOMO). Therefore, by matching appropriate electrodes and organic materials, the carrier injection energy barrier can be effectively reduced and the carrier injection efficiency can be greatly improved. Most of the traditional OLED components are designed to be bottom-emitting, the anode of which is a transparent electrode (such as IT〇), and the light of 200835015 is required to transmit the underlying glass substrate and thin film transistor (TFT). Therefore, part of the light is blocked by the TFT and the opaque wire in the capacitor to reduce the aperture ratio and the total light exit area. Many research teams have been in recent years.

Only the design of the toP-emitting 〇LED is adopted; the upper OLED adopts the cathode of k-ming and the anode is opaque metal, and the light is emitted upward without being affected by the opaque components underneath, so it can be improved The shortcomings of light being obscured by the TFT private road and greatly increasing the aperture ratio and the light exit area. However, one of the shortcomings to be overcome is that the commonly used metal anodes such as silver to 豸戈疋铭 metal have excellent renectance, and their work function is low, which greatly increases the hole injection. Energy barriers to overcome. Therefore, a feasible technique to adjust the work function of the metal anode described above while maintaining its optical properties (high reflectivity) is a current development goal of the industry. SUMMARY OF THE INVENTION In the above-mentioned background of the invention, in order to meet the requirements of the industry, the present invention provides a self-assembled monolayer film for adjusting a work function of a metal electrode and a metal electrode for fabricating an adjustable work function and an upper luminescence Application on T0p-emitting 〇rganic Light-emitting Diode (TEOLED). An object of the present invention is to enhance the work function of the electrode of the organic light-emitting diode by modifying the electrode of the organic light-emitting diode. Another object of the present invention is to reduce the energy barrier to be overcome in the injection of a hole by modifying the anode of the organic light-emitting diode. Another object of the present invention is to provide a metal electrode wit (h tunable work function). The metal electrode of the above-mentioned adjustable-to-work function can be adjusted for the purpose of adjusting the work function of the metal electrode by providing a self-assembled monolayer film on one side of the metal electrode. Still another object of the present invention is to provide a top-emitting organic light-emitting diode having metal electrodes with tunable woi (k functlon) having a metal working electrode capable of adjusting a work function. The above-mentioned upper-emitting small-molecular organic light-emitting diode system adopts the metal electrode with adjustable work function disclosed in the present invention as an anode, and the cathode end thereof is a transparent electrode. In accordance with the above objects, the present invention discloses a self-assembled monolayer film G^R-G2 for adjusting the work function of a metal electrode. Wherein G1 is SH, and _R is selected from one of the following groups or a combination thereof: an unsubstituted linear alkane, a branched alkyl group or a cyclic alkyl group; having one or more alkenyl groups, a straight bond group, a bond group or a cyclic alkyl group of the alkynyl group, and 3 as a substituent; a perylene group, a heterocyclic group, a multiple melting ring, and a multiple melting heterocyclic ring. & is a pull electron group. 200835015 [Embodiment] The direction of the invention discussed herein is a self-assembled monolayer film for adjusting the work function of a metal electrode. In order to thoroughly understand the present invention, detailed process steps or constituent structures will be set forth in the description below. Obviously, the practice of the invention is not limited to the particular details familiar to those skilled in the art. On the other hand, well-known components or process steps are not described in detail to avoid unnecessarily limiting the invention. The preferred embodiments of the present invention will be described in detail below, but the present invention can be widely applied to other systems in addition to the detailed description, and the scope of the present invention is not limited, and the scope of the following patents is quasi. A first embodiment of the present invention discloses a self-assembled monolayer film having a chemical structure of the general formula gLr_g2. Wherein G1 is SH, and R is selected from one or a combination of the following groups: unsubstituted linear alkyl, branched alkyl or cyclic alkyl; having one or more alkenyl anthracenes, alkyne Any combination of a radical alkyl group, a branched alkyl group or a cyclic filament as a substituent; a group of a group, a heterocyclic ring, a ring of a recording ring, and a multiple melting '%. 〇 is a pull electron group. In a preferred embodiment of the present embodiment, the G2 is selected from the group consisting of CN, F, C1, valence, CFH2, Cf2H% π% CC12H, CC13, CBrH2, CBr2H, CBr3, NO, and n〇2 . A second embodiment of the present invention discloses a metal electrode with tunable work function ^ a metal electrode comprising a metal electrode, and a self-assembled monolayer film on one side of the metal electrode. The above self-assembled monolayer film comprises a chemical structure of the general formula 11 200835015

a compound of Gi-R-G2, wherein the G1 is SH, and the R is selected from one or a combination of the following groups: a linear alkyl group, a branched alkyl group or a cyclic alkyl group; a linear alkyl group, a branched alkyl group or a ring selected from an alkenyl group, an alkynyl group, a dentyl group, an alkoxy group, a decyloxy group, a keto group, an alcohol group, a thiol group, an amino oxime ester or an amine group. An alkyl group; an aromatic group, a heterocyclic group, a multiple melting ring, a multiple melting heterocyclic ring, and a heterocyclic ring, and G2 • is a la-electron group. In a preferred embodiment of the present embodiment, the G2 is selected from the group consisting of CN, F, α, ΒΓ, cfh2, CF2H, CF3, CC1H2, CC12H, CCl3, CBrH2, CBr2H, CB[3, NO , N02. In another preferred embodiment of the embodiment, the basic metal electrode is silver metal. In the present embodiment, the method for forming the metal electrode of the adjustable work function comprises: (1) taking an area of about 625 square millimeters on a soda glass, using the mask technology in the foregoing The desired electrode line pattern is engraved in the area, and then the hot strip is plated with a layer of silver metal having a thickness of about (10) nanometers; and (2) the silver metal substrate d is added to an electrode modified solution towel having a concentration of about 1 liter. Scale riding for two hours. The solvent of the above electrode modification solution may be an organic solvent such as ethanol, isopropyl alcohol, or hexanyl is an organic solvent which is well known in the art. The above electrode-modified solubilized solute comprises a compound having the structure of the g1_r_G2 of the present invention. In the first embodiment of the present embodiment, the above solute has the following structure: 12

X X200835015

X = -CN CN-SAM -CF3 CF3-SAM -H Ph-SAM -OMe OMe-SAM A third embodiment of the present invention discloses a top-lighting type small molecule organic light-emitting diode having a metal electrode with an adjustable work function. Body (T〇p_emitting 〇rgan|e Light-emitting Diode, TEOLED). Referring to the second figure, it is a schematic diagram of the construction of a TEOLED element according to the present embodiment. As shown in the figure, the structure of the TE〇LED includes the first electrode 250, the hole injection layer 24, the hole transport layer 230, the electron transport layer 220, and the second electrode 210 in this order from bottom to top. The first electrode 25A described above may be an anode of the TEOLED, and the first % electrode 250 is a metal electrode capable of adjusting the work function. The first electrode mo comprises a self-assembled monolayer film on one side of the first electrode 250, not shown in the drawing. The above self-assembled monolayer film comprises a compound having a chemical structure of the general formula gLr_g2, wherein the G1 group SH, the R group is selected from the group consisting of: or a combination thereof: a linear alkyl group, a branched alkyl group or a ring a filament; containing a linear alkyl group, a branched alkyl group or a cyclic alkyl group substituted with one or more selected from a dilute group or a fast group; an aromatic group, a heterocyclic group, a multiple melting ring, And multiple melting _, G2 is a - pull electron group. In a preferred embodiment of the present embodiment, the G2 is selected from the group consisting of: (3), f, α, valence, 13 200835015 cfh2, cf2h, cf3, ccih2, cci2h, ca3, CBrH2, money 2H, coffee NO, N 〇 2. In a preferred embodiment of the embodiment, the first electrode 25 is a silver electrode. The TEOLED structure described above may further include a substrate 26 located below the first 250. The material of the substrate 260 may be glass, polymer fiber, or other substrate materials well known to those skilled in the art. - The composition of the above-described electric injection layer 240 includes 4,4,,4,,-tris(3-methylphenylphenylamin〇)triphenylamine • (m_MTDATA)' or other material having a hole injection property. The composition of the hole-passing layer 23〇 consists of α-naphthylphenylbiplieiiyl diamine (NpB) or other material with hole transport properties. The composition of the electron transport layer 22 includes tri "8_hydn" xyqUindine) alumimim (Alq), or other material having electron transport characteristics. In an example according to this embodiment, the upper layer is also a light-emitting layer. a second electrode I: a cathode of the TEOLED, and is a transparent electrode. In the second embodiment of the meal according to the embodiment of the present embodiment, the second electrode 21A may be a W layer 216, - Then 214, combined with the structure of the smashing layer. It is necessary to specify that the above-mentioned junction 'anode, cathode and luminescent layer are necessary components of the riding light-emitting diode' and the hole injection layer and electricity The hole-passing layer is a common technique for improving the luminous efficiency of (10)d components. The purpose is only to optimize the lion provided in this example [ED, not necessary components, in addition, the upper electrode, the hole injection layer, the electricity The description of the material of the hole transport layer, the electron transport layer, and the second electrode is only for the description of the preferred embodiment of the present invention. The method of the present invention is based on the scope of the patent application, and should not be limited to the foregoing description. As shown in the figure below, It is an I-V graph of a TEOLED element constructed in accordance with a preferred embodiment of the present invention and comparison results with other control groups.

In this example, the TEOLED provided by the present invention uses a self-assembled monolayer film with silver metal and CN3 overlying the silver metal (indicated in the above figure, CN_SAM/Ag and CFrSAM/Ag, respectively). anode. In addition, as shown in the figure, the other control groups used for comparison contain pure silver metal (marked in the above figure as

Ag), silver metal overlying Ag2〇 (labeled as Ag2〇/Ag in the figure above), silver metal overlying self-assembled monolayer film without substituents (labeled as ph-SAM), silver metal A self-assembled monolayer film with a push-electron substituent OMe (labeled as OMe-SAM/Ag in the above figure), and a group of conventional lower-emitting small-molecule organic light-emitting diodes with a ribbed (four) extremely anode Body (B〇tt〇m-emitting 15 200835015

Diode, BEOLED) (marked uo in the figure above). The measurement results show that under the same bias voltage, the self-assembled monolayer film with the electron-withdrawing CN on the silver electrode and the self-assembled monolayer film with the pull-electron substituent CF3 on the silver electrode are indeed A higher current density than other control components can be achieved. The only exception was the control group covering the & 〇 on the silver electrode. However, since the Ag layer overlying the silver electrode will reduce the reflectivity of the silver metal, there is a trade in the application of the anode. Moreover, the physical properties of A itself are not stable for light and heat: In contrast, according to the design of the present specification, since the self-assembled single-layer film has a reflectivity of the low-silver package, the design according to the present specification not only changes the work function but also has a wider range. Industrial application value. Privately, 7F' is the result of the pledge rate of the above-mentioned identical experimental and control components. 13⁄4 ο

16 200835015 It can be clearly seen from the figure that the silver electrode is covered with a pull-electron substituent (3) self-assembled monolayer film and the experimental group of the CF3 self-assembled monolayer film on the surface electrode and the silver electrode is overlaid on the silver electrode. The Ag2〇) test has a luminous efficiency that is much higher than that of the other control (4) components, including the lower-emitting enamel of the conventional technology. Iron As mentioned above, the effect of 作为 & 0 on silver metal will affect its reflectivity, coupled with its inherent instability to light, thus limiting its applicability as a TEOLED opaque anode.

The factory '^, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , The invention can also be widely applied to IS in other systems: it is intended to be included in the scope of the following claims without departing from the invention.

17 200835015 [Simplified description of the drawings] The first figure is a schematic diagram of a conventional OLED element structure; and the second figure is a schematic diagram of the element structure of the TEOLED according to the present specification. [Main component symbol description] 100 OLED element 110 cathode 120 electron conduction layer 130 organic light-emitting layer 140 carrier injection layer 150 anode 160 substrate 200 TEOLED element 210 second electrode 212 Ag layer 214 A1 layer 216 LiF layer 220 electron transport layer 230 Hole transport layer 240 hole injection layer 250 first electrode 260 substrate 18

Claims (1)

200835015 X. Patent application scope: 1. A self-assembled m〇nolayer (Sam) for adjusting the work function of a metal electrode, which is used to adjust the work function of the metal electrode. The assembled monolayer film comprises a compound of the general formula G^R-G2 wherein G1 is SH; R is selected from one or a combination of the following groups: linear alkyl, branched alkyl or cyclic alkane a group comprising any one of a linear alkyl group, a branched alkyl group or a cyclic alkyl group substituted with a fluorenyl group or an alkynyl group, an aromatic group, a heterocyclic group, a multiple melting ring, a multiple melting group Heterocycle; G is an electron group (8) ectr〇n-wjthdrawing group). 2. A self-assembled monolayer film for adjusting the work function of a metal electrode according to item 1 of the scope of the patent application, wherein the G2 system described above is selected from one of the following groups: cn, F, Cl, Br, CFH2, CF2H , CF3, CC1H2, CC12H, CC13, CBrH2, CBr2H, CBt3, NO, N〇2. 3. A metal electrode capable of adjusting a work function, comprising: a metal electrode; and a self-assembled monolayer (SAM) on one side of the metal electrode, wherein the self-assembled monolayer film comprises a compound of the formula dR-G2 wherein the Gi is SH; and the R is selected from one of the following groups or a combination thereof: a linear alkyl group, a branched alkyl group or a cyclic alkyl group, which contains either One or more selected from the group consisting of an alkenyl group, an alkynyl-substituted linear alkyl group, a branched alkyl group or a cyclic alkyl group, an aromatic group, a heterocyclic group, a multiple 200835015 melting ring, a multiple melting heterocyclic ring; a G2 system It is an electron-withdrawing group. 4. The work function metal electrode according to item 3 of the patent application scope, wherein the G2 is selected from one of the following groups: cn, F, C, Br, CFH2, CF2H, CF3, CC1H2, CC12H, CC13 , CBrH2, CBr2H, CBr3, NO, N02 〇5. The work function metal electrode according to item 3 of the patent application scope, wherein the metal electrode is a silver electrode. 6. A top emission light emitting diode (TEOLED) having an adjustable work function metal electrode, comprising: a metal anode; a self-assembled monolayer And a combination of the following ones of the following groups: a linear alkyl group, a branched alkyl group or a cyclic alkyl group, which contains any one of a straight-chain alkyl group, a branched alkyl group or a cyclic alkyl group substituted by an alkenyl group or an alkynyl group, aromatic a group, a heterocyclic group, a multiple melting, a multiple melting heterocyclic ring; a G2-series electron-withdrawing group; an organic light-emitting layer, the organic light-emitting layer is located in the self-assembled monolayer film And 20 200835015 a metal cathode 'the metal cathode system is located above the organic light-emitting layer. 7. The luminescent organic light-emitting diode having an adjustable work function metal electrode according to item 6 of the patent application scope, wherein the G2 system is selected from the group consisting of: CN, F, C, Br, CFH2, CF2H, %, ccm2 qing ♦ CC13, CBrH2, CBr2H, CBr3, NO, N02 〇8. According to the scope of claim 6th, the metal function of the metal electrode with adjustable work function is provided. Further comprising an electron transport layer (ETL) 〇9. The light-emitting organic light-emitting diode having an adjustable work function metal electrode according to claim 8 of the patent application scope, wherein the material of the electron transport layer comprises Alq3 [tris-(8-hydroxyquinoline) aluminum] ° 10. The light-emitting organic light-emitting diode with an adjustable work function metal electrode according to item 6 of the patent application scope, further comprising a hole transport layer (h〇le transp 〇 rt layer ; H H H H H H H H H H H H H H H H H H H H H H H H 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据 根据(a-naphthylphenylbiphenyl diamine) ° 12. The luminescent organic light-emitting diode having an adjustable work function metal electrode according to the scope of claim 6 further includes a hole injection layer (HTL) ° 21 200835015 13· According to the patent application scope 12, the illuminating organic light-emitting diode having an adjustable work function metal electrode, wherein the material of the hole injection layer is selected from one of the lower m-MTDADA column groups [4] ?4%45^tris(3-meth^ triphenylamine)] > QiPc (copper phthalocyanine) ° 14. The light-emitting organic light-emitting diode having an adjustable work function metal electrode according to the scope of claim 6 The metal anode electrode described above is a silver electrode. 15. The root shot please refine the 6th slave money to record the metal-emitting electrode above the light-emitting organic light-emitting diode, wherein the metal cathode electrode is selected from one of the following materials or a combination thereof to form a transparent electrode: UF, A1, Ag. twenty two