Classifications

• • 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]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
• • 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]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
  • H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
• • 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
  • H10K50/15—Hole transporting layers
• • 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
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K2101/00—Properties of the organic materials covered by group H10K85/00
  • H10K2101/10—Triplet emission

Definitions

• the present invention relates to a
• a radiation-emitting device having an emitter layer containing a matrix material, a radiation-emitting fluorescent emitter and an exciton scavenger.
• High-efficiency emitters with the longest possible service life are a prerequisite for the development of highly efficient organic light-emitting diodes (OLEDs) as well as for display and lighting applications.
• Decisive for a high efficiency is the quantum efficiency of the single emitter molecule and the quantum efficiency of the emitter system (of matrix and radiation emitting emitter) as a whole.
• high lifetimes can not be realized to the same degree for all emitted colors.
• Emitter layers that emit light in the violet or blue spectral range have significantly shorter lifetimes than emitter layers that emit in the green, yellow, orange or red spectral range. This applies in particular to phosphorescent emitters.
• the object of the invention is to provide a radiation-emitting device which has an emitter layer of improved quantum efficiency and increased lifetime which emits light in the violet or blue spectral region.
• the radiation-emitting device comprises a substrate, a first electrode and a second electrode, and an emitter layer arranged between the first and the second electrode, which emits (in operation) light in the violet and / or blue spectral range.
• This emitter layer contains from 0.1 to 5% by weight of a fluorescent radiation-emitting emitter (which emits in the violet or blue spectral range) and from 1 to 30% by weight of a phosphorescent exciton trap.
• the emitter layer has a matrix material (to which the data in% by weight relate).
• the weight fraction of the exciton trap is greater than that of the fluorescent emitter.
• the emission maximum of the fluorescent emitter lies in the blue or violet spectral range, that of the phosphorescent exciton scavenger in the blue, violet or ultraviolet spectral range.
• Matrix material and the fluorescent emitter also comprises a phosphorescent exciton scavenger, it is possible to improve the quantum efficiency and the power efficiency.
• the presence of the phosphorescent exciton trap and the fluorescent emitter also causes a better charge carrier balance and a lower voltage - ie an improved current efficiency.
• a “substrate” in accordance with the present invention comprises a substrate conventionally used in the art for a radiation-emitting device.
• the substrate glass, quartz, plastic films, metal, metal foils, silicon wafers or comprise another suitable substrate material.
• the radiation-emitting device is embodied for example as a so-called “bottom emitter”
• the substrate is preferably transparent and designed, for example, as a glass substrate.
• the first electrode may be deposited on the substrate.
• the "first electrode” as used herein may be an anode on the one hand.
• the anode may consist of a hole-injecting material.
• hole injecting material any hole injecting material known in the art can be used.
• the radiation-emitting device is designed, for example, as a "bottom emitter", then the anode usually consists of a transparent material.
• it may consist of transparent conductive oxides or comprise a layer thereof.
• TCOs transparent conductive oxides
• metal oxides such as zinc oxide, tin oxide, cadmium oxide, titanium oxide, indium oxide or indium tin oxide (ITO), Zn 2 SnO 4 , CdSnO 3 , ZnSnO 3 , MgIn 2 O 4 , GaInO 3 , Zn 2 In 2 O 5 or In 4 Sn 3 Oi 2 or mixtures of different transparent conductive oxides, but are not limited to these.
• the TCOs are not necessarily subject to a stoichiometric composition and may also be p- or n-doped.
• the second electrode is a cathode.
• the "cathode” may consist of an electron injecting material
• Cathode materials can be used in the art conventional cathode materials, in particular aluminum, barium, indium, silver, gold, magnesium, calcium or lithium and compounds, and alloys of these substances and mixtures of the aforementioned elements, compounds and / or alloys.
• the cathode materials may also consist entirely of one of these materials. The cathode can thus be made transparent.
• one electrode may be transparent and the other may be reflective.
• the radiation-emitting device can thus be embodied either as a "bottom emitter” or as a “top emitter”. Alternatively, both electrodes can be made transparent.
• the emitter layer of the radiation-emitting device denotes a functional layer of a matrix material which contains one or more fluorescent emitters and one or more phosphorescent exciton scavengers or consists of the matrix material, the at least one emitter and the at least one exciton scavenger.
• the phosphorescent exciton trap is a compound capable of efficient energy transfer from the matrix material.
• the excitatory scavenger then has the task of ensuring an efficient and rapid transfer of energy to the emitter material, i. Transfer excitons to this emitter material.
• the exciton scavenger is a phosphorescent compound, it does not matter that the exciton scavenger emits radiation; rather, it is essential that the exciton trap ensures good transport of the excitons (and, if possible, the charge carriers).
• the materials used as exciton scavengers always differ from the materials used as emitters.
• excitons are formed on the matrix molecules (or exciton scavengers)
• the excitons are then transferred to the (singlet state of) the fluorescent emitters, thereby enabling at least some of the triplet excitons of the phosphorescent exciton scavenger to be used on the fluorescent emitter without any effect on the excitons
• the high efficiency of the phosphorescent (for example, in the blue emitting) exciton trap can be combined with the good long-term stability of the fluorescent (in particular blue) emitter with the emitter layer according to the invention.
• emitter layers with phosphorescent emitters are used in which a high quantum efficiency is indeed to be recorded, since the triplet excitons also radiantly recombine can, but (in the case of the blue emitter) have a low long-term stability;
• emitter layers are used with blue-emitting emitters, which have a much higher long-term stability than phosphorescent blue emitters, but have a significantly lower quantum efficiency, since only singlet excitons can radiantly recombine on these emitter materials.
• a triplet exciton generated on the matrix material or the phosphorescent exciton scavenger is ultimately transferred to the singlet state of the fluorescent emitter.
• excitons are generally a mixture of triplet and singlet states.
• triplet excitons with a disintegration time ⁇ 10 ⁇ s are suitable for a transfer to the singlet level of the fluorescent emitter. The higher concentration of the exciton trap ensures an efficient transfer of energy to the fluorescent emitters.
• the lower concentration of the emitter makes it possible to prevent, especially in the case of emitters without steric hindrance, a stacking of the molecules, which can result in a redshift of the emitted spectrum.
• the high concentrations of the exciton scavenger cause, in addition to the above effects, that these exciton scavengers do not act as trap centers for the charge carriers; on the contrary, a good transport of the charge carriers can take place.
• a charge carrier transport can take place in that the matrix transports the majority charge carriers and the exciton trap transports the minority charge carriers of opposite charge (for example, in the case of a hole-transporting matrix, the electrons are transported via the LUMO of the exciton trap).
• the radiation-emitting device according to the invention therefore also has an improved current efficiency.
• the current efficiency (compared to emitter layers without exciton trap) is increased by at least 10%.
• the current efficiency is even 20% and often even 25% higher than the current efficiency of a corresponding emitter layer without the exciton scavenger according to the invention. This applies in particular to current efficiencies at high light intensities, ie light intensities which are typically greater than 1000 cd / m 2 .
• Each of the fluorescent emitter and the exciton scavenger may be embedded in a matrix material selected, for example, from the group consisting of mCP (1,3-bis (carbazol-9-yl) benzene), TCP (1,3,5-Tris (carbazol) -9-yl) benzene), TCTA (4, 4 ', 4 "-tris (carbazol-9-yl) triphenylamine), TPBi (1, 3, 5-tris (1-phenyl-1H-benzimidazole -2-yl) benzene), CBP (4,4'-bis (carbazol-9-yl) biphenyl), CDBP (4,4'-bis (9-carbazolyl) -2,2'-dimethylbiphenyl), (DMFL -CBP 4,4'-bis (carbazol-9-yl) -9,9-dimethylfluorene), FL-4CBP (4,4'-bis (carbazol-9-yl) -9,9
• Preferred matrix materials are high nitrogen content aromatic materials such as mCP, TCTA, TPBi, BCP, BPhen, CBP, CDBP and CPF (ie FL-2CBP) or metal complexes such as Alq. When using metal complexes as matrix material, they must not match the emitter material (or the exciton trap).
• metal complexes as matrix material, they must not match the emitter material (or the exciton trap).
• matrix materials which are present in mixed systems for example mixtures of one or more of the materials TCTA, mCP, CBP, CDBP or CPF with one another or mixtures with TPBi are used.
• a blue phosphorescent exciton scavenger may be selected from the group consisting of FIrPic (bis (3,5-difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium III), FIr ⁇ (Bis (48, 68 difluorophenylpyridinato) tetrakis (1-pyrazolyl) borate iridium III), mer-Ir (dpbic) 3 (mer-iridium (III) tris (1,3-diphenylbenzimidazolin-2-ylidene C, C2 ')), mer-Ir (cn-pmic) 3 (mer-iridium (III) tris (1-methyl-3-p-cyanophenyl-imidazolin-2-ylidene-C, C2 ')), mer-Rh (cn-pmic) 3 (Mer-rhodium (III) tris (1-methyl-3
• the emitter materials mentioned have their emission maximum in the blue spectral range. If in general an exciton scavenger or an emitter has several emission maxima, then the emission maximum with the greatest intensity is considered as the emission maximum in the sense of this invention. If two or more intensity-highest emission maxima exist at different wavelengths at different current intensities, the maximum at the smaller wavelength of this emission maximum applies as the emission maximum (in particular for determining the difference between the emission maximum wavelengths of the radiation-emitting emitter and the emission maximum of the exciton trap). ,
• a blue phosphorescent exciton scavenger may be selected from the group consisting of: fac-Ir (Pmb) 3 (fac-iridium (III) tris (1-phenyl-3-methylbenzimidazolin-2-ylidene C, C2 ')), mer Ir (Pmb) 3 (mer-iridium (III) tris (1-phenyl-3-methylbenzimidazolin-2-ylidene-C, C2 ')), fac-Ir (dpbic) 3 (fac-iridium (III) tris ( 1, 3-diphenyl-benzimidazolin-2-ylidene-C, C2 ') - P.
• the International Society for Optical Engineering The emission maximum of such exciton trap is usually at a wavelength of at least 390 nm.
• a compound can be used which has the emission maximum in the violet or blue spectral range.
• the emission spectrum of the emitter can have more maxima; As a rule, however, these will also be in the blue and / or violet spectral range.
• the blue fluorescent emitter for example, a compound selected from the group consisting of BCzVBi (4, 4'-bis (9-ethyl-3-carbazovinylene) -1, 1'-biphenyl), perylene, TBPe (2 , 5,8,11-tetra-tert-butylperylene), BCzVB (9H-carbazole-3,3 '- (1,4-phenylene-di-2,1-ethendiyl) bis [9-ethyl- (9C)] DPAVBi 4,4-bis [4- (di-p-tolylamino) styryl] biphenyl, DPAVB (4- (di-p-tolylamino) -4 '- [(di-p-tolylamino) styryl] stilbene), BDAVBi (4, 4 'bis [4- (diphenylamino) styryl] biphenyl), BNP3FL (N, N'--
• the emitter layer is divided into at least two partial layers. It has at least one first partial layer (that is to say partial layer (s) of a first type) in which the matrix material contains only the fluorescent radiation-emitting emitter but no phosphorescent exciton trap. Further, the emitter layer then comprises at least a second sub-layer (i.e., sub-layer (s) of a second type) in which the matrix material contains only the phosphorescent exciton scavenger but not a fluorescent radiation-emitting emitter.
• first partial layer that is to say partial layer (s) of a first type
• the emitter layer then comprises at least a second sub-layer (i.e., sub-layer (s) of a second type) in which the matrix material contains only the phosphorescent exciton scavenger but not a fluorescent radiation-emitting emitter.
• triplet excitons are first on the matrix material (or on the
• the triplet excitons can diffuse non-directionally from the molecules of the phosphorescent exciton scavenger in all directions and yet strike an interface with the other sublayer.
• the matrix material used for the respective partial layers can be the same or different.
• the matrix material containing the phosphorescent exciton scavenger will be tuned to the triplet level of the exciton trap with respect to the triplet level.
• the sub-layer may comprise the same material as the matrix material, such as a hole-blocking layer, electron-transport layer or electron-injection layer adjoining this sub-layer on the cathode side.
• An anode side adjacent to the phosphorescent excitement scavenger sub-layer may, for example, have the same matrix material as a turn on the cathode side adjacent to this sub-layer electron-blocking layer, hole transport layer or Lochinj tion layer.
• the matrix material of the sub-layer or the sub-layers, which contain the fluorescent emitter also consist of a matrix material which, although not adjacent to the previously described cathode side or anode side of these sub-layers
• Matrix material corresponds, but is selected from the matrix materials mentioned above.
• any hole-blocking and electron-transporting matrix material is suitable in particular for a sub-layer with a fluorescent emitter arranged on the cathode side, and any electron-blocking and hole-transporting matrix material for a sub-layer having fluorescent emitters arranged on the anode side.
• the matrix material may also be selected to also possess exciton-blocking properties. This has the effect of forming in the sublayer containing the exciton scavenger
• Excitons can not be transferred to the matrix material of the sub-layer with the fluorescent emitter, but is transmitted substantially only to the singlet level of the fluorescent emitter and here (in the vicinity of the interface between the sub-layers) can radiant decay.
• the emitter layer has no sub-layers (which in each case only the emitter emitters the fluorescent radiation and the
• Matrix material or only the phosphorescent exciton scavenger and the matrix material are randomly distributed over the entire emitter layer.
• the molecules of the fluorescent emitter and those of the phosphorescent exciton scavenger may be present side by side in regions (which of course do not correspond to a whole sub-layer). Further, of course, mixtures of a random distribution and an embodiment in which regions with phosphorescent exciton scavengers or fluorescent emitters are present are possible.
• the fluorescent emitter and also the phosphorescent excitonic scavenger are randomly distributed over the matrix material.
• concentration gradients may also be present in the emitter layer, see above for example, areas where the exciton scavenger is more highly concentrated alternate with areas where the fluorescent emitter is relatively more concentrated;
• regions which, however, do not yet represent a true sublayer
• exclusively exciton scavengers are contained and regions in which only the phosphorescent emitter is contained.
• This can be targeted zones are set in which mainly excitons are formed or zones in which mainly the emission takes place.
• non-radiative competing processes such as, for example, direct formation of triplet excitons on the fluorescent dopant or triplet triplet annihilation on the phosphorescent exciton trap can be minimized by the (molecular ratio) between fluorescent emitter radiation and phosphorescent exciton trap according to the invention.
• the weight fraction of the phosphorescent exciton trap is at least four times, often even at least eight times that of the fluorescent radiation emitting emitter.
• the proportion of the phosphorescent exciton scavenger is 10-20% by weight (in the context of the present invention, all data in% by weight always refer to the matrix material contained in the emitter layer). From a weight proportion of at least 10 wt .-% so much excitement scavenger is included in the matrix material that a very efficient transport of the charge carriers is made possible and therefore a significant increase in the power efficiency is recorded. From a proportion of 20% by weight, under certain circumstances it can increasingly occur that efficiency losses occur through interactions of two excitons.
• the proportion of the fluorescent emitter is 1 - 4 wt .-%. From a weight proportion of 5 wt .-% is - depending on the respective emitter - to expect a concentration quenching and therefore a significantly decreasing efficiency.
• the phosphorescent exciton trap has the emission maximum at a shorter wavelength than the radiation emitting emitter.
• the triplet level of the matrix material (Tl Ma t ⁇ x) should be higher than the triplet level of the Exzitonenflinders (Tl ExzitO nenfanger) t should again lie higher than the singlet of the fluorescent emitter (Sl Em itter) •
• the triplet excitons on the Formed matrix material transferred to the phosphorescent exciton scavenger, which then transmits the triplet excitons to the singlet state of the fluorescent emitter (and in particular can not deliver to the matrix material of a sub-layer with the fluorescent emitter - if sublayers of the emitter layer are present and these sublayers have different matrix materials) ,
• the difference between the wavelengths of the emission maximum of the radiation-emitting emitter and the emission maximum of the exciton trap is 1 nm to 100 nm, preferably at least 15 nm or at least even 30 nm to 100 nm. Then, as a rule, an efficient energy transfer cascade is also possible.
• the radiation-emitting device is characterized in that the average life of the emitter layer (at a luminance of 300 cd / m 2) compared to the average life of a radiation-emitting device, which only which differs containing that the emitter layer only phosphorescent Exzitonenfnatureer (and not the fluorescent emitter) is increased by at least 50 percent is. Often, even an increase in average life of 100 percent can be observed. Increases of up to 300 percent or up to 500 percent are also observed.
• the radiation-emitting device according to the invention then has (at a luminance of 300 cd / m 2 ) usually an average life of at least 10,000 hours, often of at least 20,000 hours. Lifetimes of 50,000 hours can also be achieved.
• the radiation emitted by the emitter layer is generated essentially by the radiation-emitting emitter. Due to the excellent charge carrier and exciton conductivity of the phosphorescent exciton trap, the excitons formed in the matrix material or on the phosphorescent exciton trap are transferred to a large extent to the fluorescent emitter material, which can be recognized, for example, from the emission spectrum.
• the intensity of the normalized emission of the emission maximum of the exciton trap in a spectrum measured for the emitter layer with exciton trap and radiation-emitting emitter is at most 40% of the intensity of the emission maximum of the radiation-emitting emitter, often at a maximum of 20%.
• the intensity of the emission maximum of the exciton trap is only a maximum of 10%, often even a maximum of 5% of the intensity of the emission maximum of the radiation-emitting emitter.
• the measured intensity ratios are usually independent from the current density, in particular at current densities between 0.5 and 10 mA / cm 2 .
• the intensity of the emission maximum of the phosphorescent exciton trap in an emitter layer with exciton scavenger and radiation-emitting emitter is also significantly higher than the emission maximum of an emitter layer containing only the exciton scavenger (in the same concentration as in the above-mentioned "mixed" system) no
• the intensity of the normalized emission of the emission maximum of the exciton trap in the emitter layer with emitter and exciton trap is then usually not more than 40%, usually not more than 20%, often not more than 10% and often even not more than 5 (measured at the same current density of, for example, 5 mA / cm 2 ) % of the normalized emission of the emission maximum of the exciton trap in a layer consisting only of the matrix material and the exciton scavenger. As described above, this is essentially due to the good exciton conductance of the exciton trap.
• the measured intensity ratios are usually independent of the current density, in particular at current densities between 0.5 and 10 mA / cm 2 .
• the light emitted by the emitter layer causes substantially the same color impression as the light emitted by an emitter layer without an exciton trap (as well as without
• Partial layers is emitted causes.
• a substantially identical color impression is understood in particular to mean that the CIE coordinates of the emitted light of an emitter layer without exciton trap (X O E / Y O E) are not substantially different from those of an emitter layer
• the good transfer of the excitons from the exciton trap to the dopant can be determined from the time-resolved wavelength-dependent emission spectra. If one compares here an emitter layer, which contains a phosphorescent exciton trap and a fluorescent emitter material, with an identical layer which in the same concentrations in each case only the exciton trap (and no partial layers) or only the radiation-emitting emitter material (and no
• Emitter material remains essentially the same or even increases slightly.
• the half-life of the emitter layer according to the invention in the emitter layer according to the invention, the half-life of
• Exciton lifetime on the exciton trap less than or equal to 10 ⁇ s, preferably less than or equal to 1 ⁇ s.
• Exciton lifetime on the exciton trap less than or equal to 10 ⁇ s, preferably less than or equal to 1 ⁇ s.
• a particularly high singlet content is recorded in the triplet excitons formed.
• the effects described above also lead to a significant increase in the external quantum efficiency of the emitter layer. Comparing the external quantum efficiency of an emitter layer with phosphorescent exciton trap and fluorescent radiation-emitting emitter with the quantum efficiency of an emitter layer containing only the fluorescent emitter (in the same Concentration) and contains no exciton trap, it is found that the quantum efficiency is increased by at least 20%. Often, even a 30% increase can be detected. With the emitter layer according to the invention, therefore, external quantum efficiencies ⁇ ext greater than 12%, often even greater than 14% can be achieved. It is even possible to achieve quantum efficiencies of more than 18%, eg 20%.
• the quantum efficiency of the emitter layer according to the invention is at least 75 percent of the quantum efficiency of an emitter layer which contains only the fluorescent emitter and no phosphorescent exciton trap (as no sublayers). In many cases, it is even the case that the quantum efficiency of the emitter layer according to the invention is equal to or higher than that of the abovementioned emitter layer which contains only the fluorescent emitter.
• the (possibly partial layers) emitter layer of the radiation-emitting device has a layer thickness of 10 to 40 nm. Emitter layers with smaller layer thicknesses are more difficult to process; In addition, from a layer thickness of 10 nm, the number of emitter centers can be optimized and thus better adapted to the lifetime of the excitons. However, a layer thickness between 5 and 10 nm may also be technically meaningful. In particular, when the emitter layers has 2, 3 or more sub-layers, becomes the layer thickness of the individual partial layers often be 5-10 nm.
• the layer thickness of the individual emitter layers is preferably in each case 10-20 nm.
• the radiation-emitting device may have at least one further emitter layer, frequently in total at least two or three emitter layers.
• such an arrangement is suitable for generating a radiation-emitting device which emits white light.
• This white light can be formed by the superimposition of the radiation emitted by the first emitter layer and the at least one further emitter layer.
• at least three emitter layers for example emitter layers which emit each in the red, green and blue spectral range
• a system which contains only two emitter layers for example a blue and an orange-emitting layer
• the different spectral ranges are defined as follows: red spectral range about 640 to 780 nm, orange
• blocking layers are present between in each case two of the emitter layers mentioned in the preceding paragraph. If the radiation-emitting device contains more than two emitter layers, a blocking layer may be present between all emitter layers, but also only between a part of the emitter layers. Such a blocking layer can serve to block excitons and thereby be designed so that their thickness is greater than the mean free path of the excitons formed in the respective adjacent layer, so that they can not get into the second layer substantially. Furthermore, the blocking layer may alternatively or simultaneously also serve at least in part of the layer for blocking charge carriers (electrons or holes). Through layers or subregions of layers which block charge carriers, a targeted adjustment of the charge carrier density can take place.
• a blocking charge carriers electrostatic charge carriers
• Blocking layer for blocking excitons and / or charge carriers may comprise or consist of one or more matrix materials, and suitable matrix materials may be selected from the matrix materials disclosed above.
• layers that block electrons may include or include one or more of the following hole transport layer materials and one or more matrix materials.
• layers may block the holes of one or more of the following materials
• Electron transport layers include or comprise (s) and one or more matrix materials.
• the radiation-emitting device is an OLED and can be used in particular as
• Lighting device or be designed as a display and have a large area formed active luminous surface.
• the radiation-emitting device according to the invention can have further functional layers.
• Such layers may include, for example, electron transport layers, electron injection layers, hole transport layers and / or hole injection layers.
• Such layers may serve to further increase the efficiency of the radiation-emitting device and be formed at one or more suitable locations of the radiation-emitting device. They may be suitable electron transport materials and / or
• Hole transporting materials and / or materials suitable for improving hole injection and materials for blocking excitons or charge carriers are Liq (8-hydroxyquinolinolato-lithium), TPBi (2, 2 ', 2''- (1, 3, 5-benzyltriyl) -tris (1-phenyl-1H-benzimidazole)), PBD (2 (4-biphenylyl) -5- (4-tert-butylphenyl) -1, 3, 4-oxadiazole), BCP (2, 9-dimethyl-4,7-diphenyl-l, 10-phenanthroline), BPhen (4, 7-diphenyl-1, 10-phenanthroline), BAIq (bis (2-methyl-8-quinolinolato) -4- (phenylphenolato) aluminum), TAZ (3- (4-biphenylyl) -4-phenyl-5-tert -butylphenyl-1,2,2-triazole), CzSi (3,6-bis (trifluoride), phosphate
• the electron transport layer (which can also serve as exciton blocking layer and / or hole blocking layer) substances are preferably selected from the group consisting of TPBi, BCP, Bphen, CzSi and TAZ and mixtures of these substances.
• suitable hole-transporting materials are NPB (N, N'-bis (naphth-1-yl) -N, N'-bis (phenyl) -benzidine, ⁇ -NPB (N, N'-bis (naphth-2-yl) N, N'-bis (phenyl) benzidine), TPD (N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) benzidine), N, N'-bis (naphthenic acid), 1-yl) -N, N'-bis (phenyl) -2,2-dimethylbenzidine, spiro-TPD (N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) -9
• Suitable materials for improving hole injection include CuPC (phthalocyanine, copper complex), TiOPC (titanium oxide phthalocyanine), m-MTDATA (4,4 ', 4 "-tris (N-3-methylphenyl-N-phenylamino) triphenylamine), 2T-NATA (4,4 ', 4 "-tris (N- (2-naphthyl) -N-phenyl-amino) triphenylamine), IT-NATA (4,4', 4" -tris (N- ( 1-naphthyl) -N-phenylamino) triphenylamine), NATA (4, 4 ', 4' '- Tris (N, N-diphenylamino) triphenylamine) and mixtures of the abovementioned substances, wherein the stated materials may optionally be doped.
• FIG. 1 shows a schematic overview of a radiation-emitting device according to the present invention.
• FIG. 2 shows a schematic representation of the energy levels of an embodiment of an OLED
• FIG. 3 shows a schematic representation of the energy levels of a further embodiment of a
• OLED structure according to the present invention having a first sub-layer with the fluorescent Radiation-emitting emitter and a second sub-layer with the phosphorescent exciton scavenger.
• FIG. 1 shows the schematic layer structure of an organic radiation-emitting component. From bottom to top, the following layer structure is realized: At the bottom is the substrate 1, which may be transparent, for example, and may also be made of glass. On top of this there is a lower electrode layer 2, which may be, for example, a transparent conductive oxide such as indium tin oxide (ITO). The lower electrode layer can act as an anode or as a cathode. Overlying this electrode layer 2 is a hole injection layer 3 over which in turn a hole transport layer 4 is arranged. Above the substrate 1, which may be transparent, for example, and may also be made of glass.
• a lower electrode layer 2 which may be, for example, a transparent conductive oxide such as indium tin oxide (ITO).
• ITO indium tin oxide
• the lower electrode layer can act as an anode or as a cathode.
• a hole injection layer 3 Overlying this electrode layer 2 is a hole injection layer 3 over which in turn a hole transport layer
• Hole transport layer 4 is the organic active layer, the emission layer 5, arranged. If the radiation-emitting device contains more than one emission layer 5, then the further emission layers, which may be separated by exciton blocking layers, follow on the first emission layer. On the one or more emission layers is the hole-blocking layer 6, on which the electron transport layer 7 and finally the electron injection layer 8 with adjacent upper
• Electrode 9 are arranged.
• the upper electrode 9 may be, for example, a metal electrode or another transparent electrode, for example, one of the above-mentioned transparent conductive oxides.
• the illustration of partial layers of the emitter layer according to the invention has been omitted for reasons of clarity.
• one or more phosphorescent exciton scavengers and one or more fluorescent radiation-emitting emitters are provided in the emission layer 5 in a matrix.
• Such a radiation-emitting component can be carried out, for example, as follows: By means of HF sputtering, an ITO layer is first deposited as an anode on a glass plate. For the deposition of the further functional layers, this substrate is introduced into a recipient; this contains several
• a source with matrix material and a source with a P-dopant are deposited together on the glass plate on which the anode is already present. Accordingly, the common deposition of dopant and matrix material for the hole transport layer takes place. Subsequently, the deposition of the emitter layer according to the invention takes place.
• a matrix material, the exciton scavenger and the at least one radiation-emitting emitter material are deposited together or in succession.
• matrix material, exciton scavenger and emitter material are deposited simultaneously.
• emitter material and exciton scavengers are not deposited simultaneously.
• matrix material and fluorescent emitters can be deposited simultaneously (first sub-layer), subsequently phosphorescent exciton scavengers and matrix material (second sub-layer), and finally matrix material and fluorescent emitters (third sub-layer).
• further contained layers such as blocking layer, electron transport layer and
• Electron injection layer is analogous.
• an aluminum layer is formed as a reflective electrode.
• the various functional layers can also be applied by means of a wet process (for example spin coating), this may be particularly useful when the layer to be applied contains a polymer.
• the layers applied first by means of a wet process and all layers arranged thereon can also be applied by vapor deposition.
• FIGS. 2 and 3 An embodiment for producing an OLED emitting blue light is given.
• the schematic structure of this blue-emitting OLED is shown in FIGS. 2 and 3.
• the blue light-emitting OLED has a hole transport layer of NPB, which is 30 nm thick, applied to the ITO anode.
• An exciton blocking layer of TAPC with a thickness of 10 nm is arranged on the hole transport layer in order to avoid a transfer of the excitons from the emitter layer to the less efficient hole transport layer.
• On the cathode of LiF / Al a 30 nm thick electron transport layer of TPBi is arranged.
• a 10 nm thick layer of Bphen which acts as an exciton blocking layer and hole blocking layer.
• the emitter layer itself comprises the matrix material TCTA into which the blue phosphorescent exciton scavenger fac-Ir (cn-pmic) 3 (energy levels in FIG. 2 denoted by dots) and the blue-fluorescent emitter DPAVBi (energy levels indicated by dashes in FIG. 2) are introduced.
• the emitter layer has a layer thickness of 30 nm.
• the excitons are then first generated on the matrix material TCTA and transferred via the phosphorescent exciton trap Ir (pmb) 3 to the fluorescent emitter DPAVBi, where it can disintegrate brilliantly.
• the exciton scavenger is present in this embodiment in a concentration of 20 wt .-%; This results in a good direct exciton formation as well as a very good transfer of excitons formed on the matrix material to the exciton trap. Furthermore, the excitons due to the high
• the triplet level of the phosphorescent exciton trap (as well as that of the matrix) can be calculated from the emission wavelength of the phosphorescence (the matrix or the exciton trap).
• the singlet level of the fluorescent emitter can be determined by measuring the emission wavelength at room temperature.
• Figure 3 shows a structure corresponding to that of Figure 2; however, the emitter layer is formed here by three partial layers.
• the phosphorescent exciton scavenger fac-Ir (pmb) 3 is (in a concentration of 20 wt .-%) in the middle, 10 nm thick layer of the
• Matrix material TCTA Adjacent thereto are two 10 nm thick layers each with the fluorescent emitter DPAVBi.
• the sublayer adjoining the middle sublayer of the emitter layer on the anode side has the matrix material TAPC, while the sublayer adjacent thereto on the cathode side comprises the matrix material Bphen.
• the energy levels of the phosphorescent exciton trap are indicated by dots characterized by dashes of the fluorescent emitter by dashes.
• excitons are formed on the matrix material TCTA (as well as on the exciton scavenger) and can then be in the direction of the interfaces to the respective adjacent sublayers, the excitons can not be delivered to the matrix material of the emitter emitters molecules be transferred to the singlet state of the fluorescent emitter and can disintegrate radiant here.

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• 2009
  • 2009-04-23 DE DE102009018647A patent/DE102009018647A1/de not_active Withdrawn
• 2010
  • 2010-04-22 EP EP10715233.2A patent/EP2422381B1/de active Active
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