Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
  • H10K10/40—Organic transistors
  • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
  • H10K10/462—Insulated gate field-effect transistors [IGFETs]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/14—Carrier transporting layers
  • H10K50/16—Electron transporting layers
  • H10K50/165—Electron transporting layers comprising dopants
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/17—Carrier injection layers
  • H10K50/171—Electron injection layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight
  • H10K85/649—Aromatic compounds comprising a hetero atom
  • H10K85/654—Aromatic compounds comprising a hetero atom comprising only nitrogen as heteroatom
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight
  • H10K85/649—Aromatic compounds comprising a hetero atom
  • H10K85/657—Polycyclic condensed heteroaromatic hydrocarbons
  • H10K85/6572—Polycyclic condensed heteroaromatic hydrocarbons comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/549—Organic PV cells

Definitions

• the present invention relates to organic electronic devices such as organic light emitting devices, organic photosensitive devices such as photovoltaic cells or photodetectors or organic transistors, for example, organic ones
• OLEDs organic light emitting diodes
• organic photosensitive devices such as photovoltaic cells or photodetectors
• problems with the charge carrier transport of the electrons and holes formed in the photoactive layer by means of exciton separation toward the electrodes problems with the charge carrier transport of the electrons and holes formed in the photoactive layer by means of exciton separation toward the electrodes.
• the charge carrier transport also plays a major role in organic electronic devices which have no application in optoelectronics, for example in organic transistors, such as organic field-effect transistors, and determines the electrical properties.
• Electron injection layer serves.
• Other authors discuss a decomposition of the cesium carbonate into CS 2 O and CO 2 . This has the consequence that the anion of the vacuum deposition
• Electron injection should play.
• An object of embodiments of the invention is to provide an organic electronic device in which the electron transport is improved.
• An anion of at least three valence includes.
• Metal salt plays a role in charge carrier transport in an organic electronic device.
• the inventors assume that the anion of the metal salt used for the production of the organically electronic device is incorporated into this device and that the valency, ie the charge of the anions, plays a role in the electron transport. In this case, compared to the cesium carbonate used in the prior art, the only one valency of 2, so a two-fold negative charge
• the electron-conducting region has at least two layers, of which a first layer comprises the matrix material and a second layer in contact with the first layer comprises the salt, this second layer being a so-called electron injection layer is preferably arranged closer to the electrode, which is connected as a cathode than the first layer, which comprises the matrix material (see for example Figure 2).
• the electron-conducting region may comprise an electron-conducting layer which contains the organic matrix material in which the salt is introduced as an n-type dopant.
• the improvements of the electrical characteristics are particularly pronounced.
• the electron-conducting layer containing the organic matrix material into which the salt is introduced as an n-type dopant may be used
• Charge carrier transport layer that transports electrodes from one subarea to another subarea of an organic electronic device.
• the electron-conducting layer can also be part of what is known as a charge-carrier-generating region, a so-called “charge generation layer (CGL)" in which, for example, a doped hole transport layer and a doped electron transport layer are present, which are provided by a thin intermediate layer of, for example, , Metal can be separated or also directly in contact with each other.
• CGL charge generation layer
• uch CGL can, for example, different OLED sub-cells in an OLED tandem cell
• salts with at least trivalent anions so for example three- or
• Cesium carbonate have advantages. For example, it is possible to use salts with at least trivalent anions
• trivalent anions is at least an order of magnitude better than salts which have only divalent anions (see for example a comparison of FIGS. 5 and 6). Due to the lower dopant concentration for salts with at least trivalent anions, an improved color impression of the electronic devices in the switched-off state also frequently results compared to salts with divalent anions. For example, doping of the matrix material BCP with cesium carbonate leads to a bluish color impression of the doped electron transport layer in the off state, while doping with, for example, cesium phosphate as an example of a salt having an at least trivalent anion in the off state of the organic electronic
• the salt is introduced as n-type dopant into the layer containing the matrix material, it is advantageous if the n-type dopant in a concentration of 1 to 50 vol%, preferably 5 to 15% by volume in the
• organic matrix material is present. Vol% concentrations in This range leads to a particularly pronounced improvement in the electrical properties, for example the current-voltage characteristics. This is particularly pronounced when using BCP as matrix material.
• the metal cation of the salt may be selected from:
• the inventors have found that, above all, monovalent metal cations, such as alkali ⁇ we metal cations Rb (I) and Cs (I) or Ag (I), Cu (I), T1 (I) and alkaline earth metal cations in combination with at least trivalent anions are good dopants. These salts of trivalent anions are also vaporizable without decomposition.
• the anion with at least triple valence can be any anion with at least triple valence.
• anionic multivalent organic anions of at least 3 valence such as the trianion of 1,3,5-benzenetricarboxylic acid or the tetraanion of
• the corresponding cesium salts of the methanetetracarboxylic acid and the methanetricarboxylic acid have the following structures:
• the organic anions may also have, for example, aromatic rings with nitrogen atoms. All of the above anions and cations can also be used in combination.
• the undissociated salt can be coordinated to the organic matrix material, for example, via the metal cation (see, for example, FIG. 4A).
• the anions may act as chelate ligands, for example, a trivalent anion such as the phosphate anion may be tridentate, and thus three
• Metal cations may have as coordination partner, in the case of cesium phosphate, for example, Cs (I).
• Cs (I) cesium phosphate
• the organic matrix material comprises a nitrogen-containing heterocyclic
• connection may be, for example, pyridine basic structures, for example 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).
• BCP 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline
• Heterocyclic compounds are particularly well suited to serve as ligands for the metal cations of the n-type dopant salt and are generally also good electron conductors.
• the organic matrix material comprises a repeating unit having the following general formula:
• the ring members A to F independently of one another represent C or N with the proviso that a maximum of two N atoms can be present
• n is an integer between 2 and 8, wherein the free valences of the ends of the repeating units can each independently be saturated by H, methyl, phenyl, 2-pyridyl, 3-pyridyl and 4-pyridyl,
• R 1 to R 4 may each independently be H, methyl, phenyl, 2-pyridyl, 3-pyridyl or 4-pyridyl and / or R 1 and R 2 or R 3 and R 4 may be mutually butadiene or
• Form azabutadiene units to form a fused 6-ring system and the repeating units can be joined between the nth and (n + l) th rings by ethylene or azomethine units, respectively, forming phenanthrene and azaphenanthrene units, respectively.
• Such oligo-pyridyl and / or oligo-pyrinidyl-arenes are particularly suitable since they are good at the dopants
• the organic matrix material can be selected from the following specific compounds and their combinations:
• Particularly preferred salts for dopants are alkali metal salts of phosphates, for example cesium phosphate.
• the subject of a further embodiment of the invention is an organic electroluminescent diode (OLED).
• OLED organic electroluminescent diode
• formed organic electronic device further comprising an organic electroluminescent layer between the electron-conducting region and one of the
• the electroluminescent (EL) layer is arranged in the layer stack of the OLED device such that the electron-conducting region is between the EL layer and the electrode connected as the cathode.
• the electroluminescent (EL) layer is arranged in the layer stack of the OLED device such that the electron-conducting region is between the EL layer and the electrode connected as the cathode.
• an OLED is ensures a particularly good electron transport from the cathode to the organic EL layer.
• organic electronic device of the present invention may also be formed as an organic photosensitive device, wherein an organic
• photoactive layer for example a bulk heterojunction between an n- and a p-type material.
• the n-type material can
• be fullerene C6o which is mixed, for example, with p-type polymers such as polyparaphenylenevinylene or formed in separate superposed layers.
• p-type polymers such as polyparaphenylenevinylene or formed in separate superposed layers.
• photosensitive device is also the
• Device is an organic transistor, for example a field effect transistor, in which an organic semiconductor, which may for example comprise the electron-conducting layer according to the invention with the salt as dopant, may be present (see for example Fig. 9).
• an electron-conducting layer may, for example, be in contact with the
• Electrodes of the transistor are in order to achieve an improvement in the injection of charge carriers. Especially,
• the electron-conducting layer is used in n-channel transistors.
• the invention further provides a process for producing an organic electronic device with the process steps:
• An anion of at least three valence includes.
• the electron-conducting region represents a layer of an organic matrix material with the salt as n-type dopant, a co-evaporation or co-evaporation of the salt and the
• the salts with the at least trivalent anion are readily vaporizable, with little or no residual being frequently observed. Due to the high at least three times negative
• Cesium phosphate are similar to those of the salt lithium fluoride, which, however, has only a single negatively charged fluoride anion. That known from the prior art Cesium carbonate, in contrast, forms the same
• the invention also provides an electron-conducting composition comprising:
• An electron-conducting matrix material may include the compounds already mentioned above, and
• Figure 1 shows a schematic cross section of a
• Embodiment of an organic electronic device according to the invention either as an organic photosensitive device or as an organic electroluminescent device
• OLED organic matrix
• Figure 2 shows a schematic cross section of a
• Another embodiment of an organic electronic device according to the invention in which the organic matrix material and the salt are arranged in separate layers.
• Figures 3A and 3B show in perspective view and in
• FIG. 5 shows the current-voltage characteristics of a
• FIG. 7 shows two different current-voltage characteristics
• Figure 8 shows the chemical structures of possible
• electroluminescent materials that can be used in OLED devices according to the invention.
• Figure 9 shows a schematic cross section of a
• Figure 10 shows the current-voltage characteristics of an electrode arranged between two electron-conducting layer having different dopant concentrations ⁇ on the cesium salt of
• Methanetetracarboxylic acid (CS 4 C 5 O 8 ) in BCP and other matrix materials.
• FIG. 1 shows in cross section an organic electronic device with a substrate 1, a first electrode 2 and a second electrode with the reference numeral 4 and an organic functional layer 5, which in the case of an OLED comprises an organic electroluminescent (EL) layer, or Case of an organic photosensitive device includes a photoactive layer.
• an organic functional layer 5 and the second electrode 4 which is connected as a cathode, there is an electron-conducting region, which comprises an organic matrix material 3B and a salt 3A with an at least trivalent anion, which is incorporated as an n-dopant in the layer 3B of FIG organic matrix ⁇ materials is introduced.
• an organic matrix material 3B and a salt 3A with an at least trivalent anion which is incorporated as an n-dopant in the layer 3B of FIG organic matrix ⁇ materials is introduced.
• the electronic apparatus has due to the electron ⁇ conductive region 3A and 3B, an improved charge transport capability ⁇ for electrons between the cathode 4 and the organic functional layer 5 on.
• an OLED in such a device the electron transport from the cathode 4 to the organic electroluminescent layer 5 is improved, whereas in the case of an organic photoactive layer, the removal of electrons formed in the photoactive layer 5 towards the cathode 4 is improved.
• the schematic cross-sectional view shown in Figure 2 shows an alternative to Figure 1 embodiment of the organic electronic device. In contrast to FIG.
• the electron-conducting region is embodied as two separate layers, namely a layer comprising the matrix material 3b and a separate layer 3a, which comprises the salt with the anion of at least trivalent valency. Otherwise, all other layers are unchanged from the illustration in FIG. In the devices shown in Figure 1 and Figure 2 additional layers may be present.
• FIGS. 3A and 3B show a further embodiment of a perspective view and in cross-section
• electroluminescent layer 5 and the electron-conducting layer 3A, 3B according to the invention there are also further layers, for example a hole-transporting layer 9, a hole injection layer 7, a hole blocking layer 6 and an electron injection layer 8, which provide effective charge carrier transport from the anode 2 and the cathode 4 to the electroluminescent layer guarantee.
• Figure 4A shows a possibility of coordination between the salt with the at least trivalent anion and a
• FIG. 4A shows that the salt cesium phosphate is not dissociated and is incorporated into the organic matrix material, the salt coordinating via the cesium cations BCP as ligand.
• the trivalent phosphate anion acts, the three cesium cations binds, as tridentate chelate ligand.
• Each cesium cation of the cesium phosphate salt can coordinate two or three BCP molecules as ligands.
• Figure 4B shows another way of coordinating cesium phosphate as salt with BCP as organic
• Figure 5 shows the variation of the current-voltage characteristics of BCP layers disposed between an ITO anode and an aluminum cathode with changes in the dopant concentration of cesium phosphate as doping n-type dopant relative to BCP as the matrix material.
• Cesium phosphate relative to the rate of evaporation of BCP was 5%, 10%, 15% and 30% (co-evaporation of BCP and cesium phosphate).
• On the doped BCP layer was evaporated as the cathode aluminum.
• the current voltage characteristic indicated by the reference numeral 50 denotes the IU behavior of a pure undoped BCP layer which is arranged between the ITO anode and the aluminum cathode.
• current-voltage characteristic ⁇ characterizes the IV characteristic of a BCP layer that contains 5% by volume of cesium phosphate as the n-type dopant.
• the voltage characteristic curve with an increase of the dopant concentration to 10% by volume in accordance with the current-voltage characteristic 10 and with an increase to 15% by volume in accordance with the current-voltage characteristic curve 20. It can be observed that at a dopant concentration of 30% by volume the electrical properties deteriorate slightly (with 40 marked current voltage ⁇ characteristic). It can be observed that in one
• Figure 6 shows the current-voltage characteristics of a BCP layer sandwiched between an ITO anode layer and an aluminum cathode layer and doped with different vol% concentrations of CS 2 CO 3 .
• characterized current-voltage characteristic represents the current-voltage behavior of a pure BCP-layer, while the designated 21 line doping with 1% by volume
• FIGS. 5 and 6 thus clearly show that the use of a dopant salt with a trivalent anion has marked improvements compared to the use of a dopant salt with a divalent anion
• FIG. 7 shows current-voltage characteristics of the BCP samples already described in connection with FIG. 5 before and after the load with a current of 1 mA over 66 hours. A sample was used, the one with 15% by volume
• Cesium phosphate doped BCP layer disposed between an ITO anode and an aluminum cathode. Marked with the reference numeral 61 current-voltage characteristic ⁇ shows the current-voltage behavior from exposure to 1 mA and the current marked with 60 ⁇ voltage characteristic of the IV characteristic after exposure to 1 mA over 66 hours. It can be clearly seen that the high current load does not lead to a noticeable degradation of the BCP layer, so that it can be assumed that organic electronic devices with the inventive electron-transporting region have a high energy density
• Figure 8 shows the structure of three organic compounds as they can be used for example in an OLED.
• the first structural formula shows NPB ( ⁇ , ⁇ '-di (naphthyl-1-yl) -N-N'-diphenylbenzidine), which may be mentioned, for example, as
• the Ir complex can be used, for example, as a red phosphorescent dye in an OLED.
• the third structural formula shows TPBI (1, 3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene), the organic
• Compound III This compound can be used inter alia for the hole-blocking layer as well as for the electron-conducting layer 3A, 3B as matrix material.
• FIG. 9 shows a further schematic cross section
• Embodiment of an organic electronic device which is designed here as an organic field effect transistor.
• the first electrode 2 is arranged, which is formed as a gate electrode layer.
• the first electrode 2 is followed by an insulator layer 60, which may comprise, for example, a dielectric.
• the second electrode 4 is formed as a separate source / drain contact layer. Between the separated
• Source / drain contact layers is a semiconductor 80
• the organic field effect transistor further comprises a cover layer 70, which may serve for example for encapsulation.
• the second electrode 4, the separate source / drain contact layers may also comprise the electron-conducting regions and compositions according to the invention.
• the electron-conducting layer on the Surface of the electrodes 4 may be arranged and the injection of electrons from these electrodes 4 favor.
• Figure 10 shows current-voltage characteristics of devices analogous in construction to those already described in connection with Figure 5.
• devices were made in which various matrix materials were doped with the cesium salt of methane tetracarboxylic acid (CS 4 C 5 O 8 ).
• cesium phosphate 200nm were doped by co-evaporation
• the current-voltage characteristic marked 70 represents the current-voltage behavior of a pure BCP layer, while the line designated 75 represents a doping of 5% by volume.
• Cesium-methane-tetracarboxylic acid in BCP was measured when doping with 15% by volume of cesium-methanetetracarboxylic acid in BCP and the current-voltage characteristic 85 was obtained by doping the matrix material ETM-033 with 5% by volume of cesium-methanetetracarboxylic acid.
• the IU characteristic designated 90 was obtained in a doping of the matrix material ETM-033 with 15% by volume of cesium-Methantetra ⁇ carboxylic acid.
• the two very similar current-voltage characteristics 95 and 100 characterize the IU characteristic of LG201 or an ET7 layer, each doped with 5 vol% cesium methane tetracarboxylic acid.
• the horizontal ranges of the curves for ET7 and LG201 do not represent a current limit through the device, but represent the current limit of the measuring device.
• the dried ether phase is completely freed from ether on a rotary evaporator and the remaining oil is fractionated in vacuo Kp: 170 ° C / 12mbar.
• the methanetetacarboxylic acid tetraethyl ester fraction is stirred with the equivalent amount of cesium hydroxide in water until the biphasic mixture is dissolved in each other.
• the Solvent water is distilled off completely using a rotary evaporator and the residue crystallized from methanol umkristalli ⁇ Siert.
• the crystallizing white product is filtered off and dried after drying in vacuo in a Drainsublimator in argon stream vacuum (10-2 mbar) at 300 ° C.
• the dried cesium salt of methanetetracarboxylic acid is harvested in a glovebox without first exposing it to the air (greyish-white powder with a sublimation temperature> 625 ° C.).
• the cesium salt of methane tricarboxylic acid can be prepared, but the synthesis is stopped in the first alkylation.

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• 2009
  • 2009-09-30 DE DE102009047880A patent/DE102009047880A1/de not_active Withdrawn
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