WO2022178636A1

WO2022178636A1 - Boron subphthalocyanine-subnaphthalocyanine hybrids for oled displays

Info

Publication number: WO2022178636A1
Application number: PCT/CA2022/050265
Authority: WO
Inventors: Timothy Bender; Nina FARAC; Richard Garner; Trevor PLINT
Original assignee: The Governing Council Of The University Of Toronto
Priority date: 2021-02-26
Filing date: 2022-02-24
Publication date: 2022-09-01

Abstract

Described herein are light emitting compositions, of any of the following molecular templates:,, or wherein A, B, M, N, O, and P are substituents from F, Cl, Br, I, O-R, N-R2, S-R, NO2, SO3-R, SO2-R, SeO3-R, SeO2-R, PO3-R, PO2-R, C-R3, or R; For A, B, N, and P, n is between zero and four, alternatively for M, and O, n is between zero and two; X is a substituent from F, Cl, Br, I, O, N, S, Se, P, phenyl, or C-R3; and, if X is N or P, then both Y and Z are each R, phenyl, or Si-R3, and if X is O, S, or Se, then Y is R, phenyl, or Si-R3 and Z is not present in any form, including hydrogen, and if X is a phenyl group, then that phenyl group may incorporate H, F, Cl, Br, I, O, N, or S substituents; and in an absence of any substituent, hydrogen is provided.

Description

BORON SUBPHTHALOCYANINE-SUBNAPHTHALOCYANINE HYBRIDS FOR OLED DISPLAYS

FIELD OF DISCLOSURE

[0001] The present disclosure relates to light emitting materials. More particularly, the present disclosure relates to organic light emitting materials.

BACKGROUND

[0002] Electronic displays use blue, green, and red pixels to create a range of colours referred to as the gamut. There are several industry standards governing colour gamut, for example the International Telecommunication Union’s (ITU) Rec. 709 standard of 1990, and its BT.2020 standard of 2012. These standards establish a standardized language and specification system which allows manufacturers, distributors, and consumers of displays to understand and compare display products. Achieving or approaching more recent standards such as BT.2020 results in a better display providing a more realistic and appealing image.

[0003] Organic light emitting diodes (OLEDs) are a light-generating technology that has been rapidly displacing the previous light emitting diode (LED) technology in applications such as display. OLEDs’ primary advantages over LEDs include improved black-to-white contrast ratios (since OLEDs turn off a pixel to create a black) and improved power efficiency, due to elimination of the always-on LED/LCD backlight. Display OLEDs use specific light emitting materials for each of the blue, green, and red pixels, and it is desirable for those materials to be tuneable for specific device and application requirements.

[0004] While OLED displays have met the Rec. 709 standard’s colour gamut, they have been unable to meet the BT.2020 standard’s requirement for a deeper red pixel. This inhibits a range and visual appeal of colours that current OLED displays can produce.

[0005] Current light emitting materials for OLEDs typically require colour filtration which reduces the device’s efficiency. The filter requirement arises due to the use of phosphorescent light emitting molecules, which emit a wide range of wavelengths that reduce the purity of the red light produced. As a human eye sees orange and yellow colours more readily than it sees an equal amount of red light, the impure wavelengths of light cause the red pixel to appear orange-red. [0006] As current OLEDs have colour generating limits with current light generating materials, current OLEDs may not be suitable for light applications requiring a “pure red” emission. For example, OLED devices used as signalling lamps in vehicles use colour filtration for their emitted red light to enable them to provide a red-spectrum colour, which is required by vehicles’ safety standards for stop lamps.

[0007] Fluorescent materials are a type of light emitting compound demonstrating significantly narrower and therefore more pure emission spectra, in comparison to phosphorescent materials. Their spectra characteristics make them well-suited for use as narrow-band emitters in display industries.

[0008] While low efficiencies of fluorescent emission OLEDs compared to phosphorescent emission OLEDs have limited use of OLEDs in displays, recent developments have improved their efficiencies. For example, Hajime Nakanotani et al (Nature Communications, 2014, 5, Article 4016), incorporated by reference herein its entirety, demonstrates a molecule exhibiting a phenomenon called “Thermally Activated Delayed Fluorescence” (TADF). While this molecule may be used with a fluorescent emitter molecule to improve the efficiency of the OLED, the energy levels and spectra of the two molecules need to be well-aligned. Currently available red fluorescent emitters are not reliably and easily paired with available TADF materials. In part, this is due to the design challenges of creating TADF materials that work well within the orange and red colour regions, and in part this is because the typical design strategies for red fluorescent materials do not produce materials suitable for pairing with TADF materials.

[0009] Patent Cooperation Treaty (PCT) patent publication no. WO2019056133A1 , incorporated by reference herein, describes two families of fluorescent materials, comprising the boron subphthalocyanines and boron subnaphthalocyanines respectively, and several light emission applications. While these materials may be modified to produce specific emission points, they have a limited range of red colours, again, which are specifically useful for reds in OLED displays.

[0010] As such, there are deficiencies in current OLED technologies relating to generation of certain spectra, including in the orange and red colours.

SUMMARY

[0011] In an aspect of the disclosure, a light emitting composition is provided comprising a light emitting agent comprising at least one boron sub-omni-phthalocyanine (BsubOc) derivative. Particular aspects provide a class of BsubOc material as shown in two exemplary classes of BsubOc shown below.

[0012] For an embodiment, for each material class, the bolded letters A, B, M, N, O, P, X, Y, and Z each refer to distinct sets of molecular substituents/fragments. These bolded letters are used as stand-ins for substituents, rather than elemental symbols or other references for specific fragments. The central boron and nitrogen atoms and the carbon and hydrogen atoms as implied by the skeletal formula will be known to those skilled in the art as always present as depicted. Each set of molecular substituents may comprise one or more types of substituent, such that any material derivative in the BsubOc material class may comprise any combination of the molecular substituents provided by the formulae below, limited by physical considerations including but not limited to steric hindrance, reactivity between proposed substituents, or other physical considerations as would be known to one skilled in the art.

[0013] The following formulae of the exemplary molecular substituents show their elemental symbols, except for the symbol R, which by chemical nomenclature convention known to those skilled in the art, refers to zero or more carbon atoms, and optionally hydrogen atoms, in any structural configuration, and in this case refers inclusively to a minimum of zero carbons and a maximum of 18 carbons.

[0014] For an embodiment, the subscript n indicates the quantity of the indicated substituent which may be found at the specific location, with dashed lines leading to the centers of carbon rings indicating that the substituents may be located on a given ring in any or all substituent points, and where any absence of a specific substituent indicates the presence of hydrogen. [0015] For an embodiment, A refers to a set of substituents comprising any of F, Cl, Br, I, O- R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0016] For an embodiment, B refers to a set of substituents comprising any of F, Cl, Br, I, O- R, N-R₂, S-R, N0₂, S0₃-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0017] For an embodiment, M refers to a set of substituents comprising any of F, Cl, Br, I, O- R, N-R₂, S-R, N0₂, S0₃-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R, where n may be zero, one, or two.

[0018] For an embodiment, N refers to a set of substituents comprising any of F, Cl, Br, I, O- R, N-R₂, S-R, N0₂, S0₃-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0019] For an embodiment, the symbol O refers to a set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, S0₃-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R, where n may be zero, one, or two.

[0020] For an embodiment, P refers to a set of substituents comprising any of F, Cl, Br, I, O- R, N-R₂, S-R, N0₂, S0₃-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0021] For an embodiment, X refers to a substituent comprising any of F, Cl, Br, I, O, N, S,

Se, P, phenyl, or C-R₃, where, if X is N or P, then both Y and Z are each R, phenyl, or Si-R₃, and where if X is O, S, or Se, then Y is R, phenyl, or Si-R₃ and Z is not present in any form, including hydrogen, and where if X is a phenyl group, then that phenyl group may incorporate H, F, Cl, Br, I, O, N, or S substituents.

[0022] Where A, B, N, or P are catechol, n is one, and the catechol is connected to the lobe via two ether linkages formed from catechol’s OH groups.

[0023] For an embodiment, in an absence of any other substituent, hydrogen is provided.

[0024] In another aspect, a top-emission OLED structure comprising a light emitting composition of an embodiment is provided. The structure may comprise: a transparent cathode; an emissive layer comprising a host and a BsubOc fluorescent dopant; and a reflective anode. The structure may further comprise one or more of: an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; a host buffer layer; an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; and a host buffer layer.

[0025] In another aspect, the following molecule shows a basic structure for which all substituents are hydrogen except the axial substituent, which here is Cl representing chlorine.

[0026] In an embodiment, the light emitting composition may further comprise a host material.

[0027] In an embodiment, the light emitting composition may further comprise a material capable of thermally assisted delayed fluorescence.

[0028] In an embodiment, the light emitting composition may comprise at least one boron sub-omni-phthalocyanine derivative.

[0029] In another aspect of an embodiment, there is provided an organic light emitting diode (OLED) comprising an emissive material comprising at least one boron sub-omni- phthalocyanine (BsubOc) derivative.

[0030] In an embodiment, the OLED may include an electron transport layer (ETL); and a hole transport layer (HTL).

[0031] In an embodiment, the OLED may include a material capable of thermally assisted delayed fluorescence. In an embodiment, the OLED may further include other emissive materials, the combined emission of which produces white light. In an embodiment, a top- emission OLED structure comprising the light emitting composition may be provided where the structure comprises: a transparent cathode; an emissive layer comprising a host, a TADF dopant, and a BsubOc fluorescent dopant; and a reflective anode. Further, the structure may further comprise one or more of: an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; a host buffer layer; an electron blocking layer; a hole transport layer containing a hole transport dopant; an organic injection material; an inorganic injection material; and a backplane or substrate.

[0032] In an embodiment, the OLED may produce red, orange, or infrared light.

[0033] In an embodiment, the OLED may produce light near to the BT.2020 standard for red, with a CIE 1931 coordinate near to (0.708, 0.292).

[0034] In an embodiment, the OLED may be a pixel of a display.

[0035] In an embodiment, the OLED may be part of a signalling lamp of a vehicle, an illuminated indicator, or a sign.

[0036] In other aspects, various combinations of sets and subsets of the above aspects are provided.

BRIEF DESCRIPTION OF DRAWINGS

[0037] Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0038] Fig. 1 shows diagrams of embodiments of exemplary molecular structures for two families of BsubOc molecules and for a basic molecular structure with only hydrogen peripheral substituents and a chloride axial substituent;

[0039] Figs. 2a-2h collectively show additional exemplary molecular structures of BsubOc molecules of Fig. 1, according to additional embodiments, with Fig. 2h listing structures of Figs. 2a-2g in a table;

[0040] Fig. 3 is a graph showing exemplary wide absorption spectra and narrow emission spectra of a BsubOc molecule of Fig.1 in a solvent;

[0041] Fig. 4a is a diagram showing an architecture of an exemplary device with charge transport layers relative to an emissive layer comprising a BsubOc molecule of Fig.1 , according to an embodiment;

[0042] Fig. 4b is a graph showing a CIE colour point (via a black circle) of an OLED of Fig.

4a comprising a BsubOc molecule of Fig.1 , with the gamut of the BT.2020 colour spectrum displayed in gradient colour, according to an embodiment; [0043] Fig. 5 is a graph showing fluorine NMR data, illustrating relative quantities of fluorine on a BsubOc molecule of Fig.1 ;

[0044] Fig. 6 is a graph showing proton NMR data, illustrating relative quantities of hydrogen on a BsubOc molecule of Fig.1 ;

[0045] Fig. 7 shows two exemplary diagrams of OLED architectures, where the same materials are used in each parallel element of both OLEDs except for the emissive layer elements, which comprise differing BsubOc molecules of Fig.1 , according to an embodiment;

[0046] Fig. 8 is a diagram showing an OLED architecture providing a performance enhancement over the OLED of Fig.4, which similarly comprises a BsubOc molecule of Fig.1 , according to an embodiment;

[0047] Fig. 9 is a diagram showing an exemplary OLED architecture having multiple emissive layers each comprising a BsubOc molecule of Fig.1 , according to an embodiment; and

[0048] Fig. 10 is a diagram showing bottom-emission OLED architectures, one of which comprises an emissive layer comprising a BsubOc molecule of Fig.1 , according to an embodiment.

DETAILED DESCRIPTION

[0049] Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure. In the description which follows, like parts are marked throughout the specification and the drawings with the same respective reference numerals.

[0050] As well, for this disclosure the conjunction “and / or” will be understood to indicate that any one or more of the conjoined items may occur and that a selection of items is not mutually exclusive, unless otherwise expressly stated. The conjunction is used as an inclusive "or". Terms, Standards, Groups, and Ranges

[0051] As used herein, the term “turn on voltage” refers to a minimum voltage at which luminance for an OLED exceeds 1 cd/m².

[0052] Various industry standards are used to identify characteristics of generated colours, known to those of skill in the art. The CIE 1931 (x,y) system defines one standard for color definitions, which converts visible spectral profiles into an individual point in Cartesian coordinates. The BT.2020 standard for red in the CIE 1931 coordinate system is (0.708, 0.292).

[0053] Unless otherwise specified, any specified range or group includes each and every member of a range or group individually, as well as each and every possible sub-range or sub group encompassed therein, and likewise with respect to any sub-ranges or sub-groups therein. Unless otherwise specified, any specified range is considered an inclusive range where the endpoints of the range are included in the specified range.

[0054] In this disclosure, where a range, threshold, time or expected value is provided as an approximate value (for example, when a range is qualified with the word “approximately”), a range of values will be understood to be valid for that value. For example, for a threshold stated as an approximate value, a range of about 25% larger and 25% smaller than the stated value may be used, but this depends on the type of value. OLED layer thicknesses may vary by more than 50% or more than 100% depending on the specific layer, in accordance with the needs to balance charge and manage cavity resonance. Reported peak wavelengths may vary by about 1 to 2%, but larger shifts will perceptibly impact colour. Generally, an appropriate definition of “approximate” for a given type of value is one which a person skilled in the art would describe as such. Thresholds, range limits, times, values, measurements and dimensions of features are illustrative of embodiments and are not limiting unless noted. Further, as examples, a “sufficient” match or a “near” value with a given output or threshold may be a value that is within the provided threshold, having regard to the approximate value applicable to the threshold and the understood range of values (over and under) that may be applied for that threshold.

Compounds of embodiments

[0055] Briefly, the disclosure describes compounds, materials and uses of such materials and compounds that produce red light and derivative materials and compounds that produce an orange or an infrared (IR) light. The energy levels and spectra may be adjusted through a number of variations in the synthesis of these compounds (with their resulting molecular structures). Such adjustments may be provided to produce specific spectra for specific industrial applications, such as pairing with a TADF-capable material.

[0056] TADF materials are known to be able to convert triplet excitons into singlet excitons by thermally assisted delayed fluorescence in a manner similar to phosphorescent materials, without requiring a heavy atom. They can be paired with fluorescent emitters, through matching energy levels and spectra, in order to enable energy transfer to the fluorescent emitter for photon emission. Some TADF materials use a single molecule with carefully balanced triplet and singlet energy levels to enable triplet conversion, while other TADF materials are comprised of multiple molecules which form exciplexes leading to the same effect.

[0057] An aspect of the disclosure presents a variety of red fluorescent emitters that provide fine control of molecular energy levels and spectra, facilitating efficient pairings with TADF materials.

[0058] An aspect of the disclosure utilizes a class of material with similarities to both boron subphthalocyanines and subnaphthalocyanines. For convenience, the disclosure identifies these materials as “Boron sub-Omni-phthalocyanines” (BsubOcs). As disclosed herein,

BsubOcs produce a narrow red emission spectra in a range necessary to produce “pure” red light, with other derivatives able to produce orange or infrared light. Their energy levels and spectra may be adjusted through control of variations for the synthetic process and resulting molecular structure, so that they may be tuned for specific applications, such as pairing with a TADF-capable material. BsubOcs are a synthetically versatile class of bowl-shaped organic semiconductor molecules having electro-optical properties useful for applications in organic electronics. There are additional applications when used in light emitting compositions with TADF-capable materials, due to the BsubOc’s high extinction coefficients and rigid structures. These properties assist in the Forster Resonance Energy Transfer process and avoid harmful interactions with other molecules in the OLED.

Compositions

[0059] In an aspect, there is provided a light emitting composition comprising a light emitting agent comprising at least one BsubOc derivative as set out by either molecule shown below: [0060] Referring to Fig. 1, exemplary molecular structures 100a and 100b for an embodiment are shown of BsubOc materials. In structures 100a and 100b, A, B, M, N, O, P, X, Y, and Z each refer to sets of molecular substituents/fragments, where each molecular substituent comprises one or more atoms, and each set of substituents may comprise one or more types of substituent. As noted earlier, these bolded letters are used as stand-ins for substituents, rather than elemental symbols or other references for specific fragments. The central boron and nitrogen atoms and the carbon and hydrogen atoms as implied by the skeletal formula will be to those skilled in the art always present as depicted. As such, a material derivative in the BsubOc material class for an embodiment may comprise any combination of the provided molecular substituents, with one or more substituents chosen from each set for each indicated location; and with substituents provided by the formulae below, limited by physical considerations including, but not limited to, steric hindrance, reactivity between proposed substituents, or other physical considerations as would be known to one skilled in the art. Structure 100a shows a molecular template for BsubOd. Structure 100b shows a molecular template for BsubOc2.

[0061] In structures 100a and 100b, their molecular substituents are identified according to their elemental symbols, except for the symbol R, which by convention refers to zero or more carbon atoms, and optionally hydrogen atoms, in any structural configuration, and for embodiments refers inclusively to a minimum of zero carbons and a maximum of 18 carbons.

[0062] For structures 100a and 100b, the subscript n indicates the quantity of the indicated substituent which may be provided at the specific location, with dashed lines leading to the centers of carbon rings indicating that the substituents are located on the ring, and where any absence of a specific substituent indicates presence of hydrogen. [0063] In another aspect, structure 100c (shown below) shows a basic structure for which all substituents are hydrogen except the axial substituent, which for structure 100c is Cl, representing chlorine.

[0064] For structures 100a and 100b, A refers to substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, NO₂, SO₃-R, SO₂-R, Se0₃-R, Se02-R, P03-R, PO₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0065] For structure 100a, B refers to substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, NO2, SO3-R, SO2-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0066] For structures 100a and 100b, M refers to substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, NO2, SO3-R, SO2-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R, where n may be zero, one, or two.

[0067] For structures 100a and 100b, N refers to substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, NO₂, SO₃-R, SO₂-R, Se0₃-R, Se02-R, PO₃-R, PO₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0068] For structure 100b, O refers to substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, NO2, SO3-R, SO2-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R, where n may be zero, one, or two.

[0069] For structure 100b, P refers to substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, NO2, SO3-R, SO2-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, catechol, or R, where n may be zero, one, two, three, or four.

[0070] For structures 100a and 100b, X refers to substituents comprising any of F, Cl, Br, I, O, N, S, Se, P, phenyl, or C-R₃, where, if X is N or P, then both Y and Z are each either R, phenyl, or Si-R₃, and if X is O, S, or Se, then Y is R, phenyl, or Si-R₃ and Z is not present in any form, including hydrogen, and where if X is a phenyl group, then that phenyl group may incorporate H, F, Cl, Br, I, O, N, or S substituents.

[0071] For structures 100a and 100b, where A, B, N, or P are catechol, n is one and the catechol is connected to the lobe via two ether linkages formed from catechol’s OH groups.

[0072] For an embodiment, in an absence of any substituent, hydrogen is provided.

[0073] Figs. 2a-2g in each set of structures 200a-200g, demonstrate exemplary individual structures of BsubOc materials according to embodiments of Fig. 1. Figs. 2a-2g are not exhaustive representations of all such structures. Fig. 2h provides a table of names of the exemplary structures in Figs. 2a-2g.

Exemplary Properties

[0074] Fig. 3 shows graph 300 for BsubOc molecule 302, showing its exemplary wide absorption spectra and narrow emission spectra, with intensity on y-axis 304 and wavelength on axis 306. Optical absorbance spectra graph 308 shows a peak absorption at slightly less than approximately 538 nm. Fluorescence emission spectra graph shows a peak emission at around approximately 538 nm.

[0075] The wide absorption spectra of the BsubOcs assists in the Forster Resonance Energy Transfer process, which in part depends upon overlap between the emission spectra of the source molecule (in this case a TADF dopant, when present) and the absorption spectra of the destination molecule (in this case the BsubOc fluorescent dopant). A greater degree of spectral overlap increases efficiency of the process. In an embodiment containing a TADF dopant, where energy is transferred from the TADF dopant to the fluorescent dopant, this improves the overall electrical efficiency of the device.

[0076] The narrow emission spectra of the BsubOcs enables them to produce more of a desired wavelength and less of undesired wavelengths, such that a greater fraction of their generated photons fall within an acceptable range of wavelengths about the peak emission wavelength. Their Full Width at Half Maximum (FWHM) is typically less than 40 nanometers, while the FWHM of phosphor or TADF emitters is typically much higher.

[0077] BsubOcs are structural variants of BsubPc with extended p conjugation on one or two of the molecule’s three lobes. This results in a more moderately red-shifted absorption and emission than what is found with BsubNc, where all three lobes are extended. BsubOc has been previously used as a medical imaging fluorophore by Durfee et al , Tetrahedron Letters, 1999, 40, 8055-8058, which is herein incorporated by reference in its entirety. BsubOc has not previously been employed in an organic electronic device, and the advantages of varying the synthetic processes to tune the electronic properties of the synthesized material have not been previously explored.

[0078] The substituents around the periphery of a molecule may be changed to adjust its optical properties, as represented in the Composition section by A, B, M, N, O, and P. For example, peripheral substituents may push or pull electron density away from the p conjugated central structure, which blue-shifts or redshifts the emission. This enables other embodiments of a molecule to be tailored for an application-specific emission and colour point without necessitating substantial alteration to its other physical properties. The substituent in the axial position, represented in the Composition section by X, Y, and Z may be used to adjust the orientability of the molecule in film, or change solubility properties, without significant impact on optical properties. Orientability of the molecule is known to benefit the efficiency of OLED devices by increasing the fraction of emitted photons which can escape the device substrate, otherwise referred to as photon outcoupling. Improving the solubility of the molecule enables solution processing as a method of manufacturing the OLED device, rather than the more common physical vapour deposition methods. Use of a BsubNc-type lobe for either one or two of the three lobes allows a coarse adjustment of properties between the two classes of BsubOc molecules. These effects are presented as examples, and the effects produced are not limited to the above.

[0079] Synthetically, various BsubOcs are created by use of different yet selected precursors known as phthalonitrile(s) and dicyanonaphthalene(s), which on combination create BsubOcs. Modifications of the structure of precursors result in modifications to the BsubOc product, though care should be taken to minimize unwanted reactions with other functional groups. This may mean selecting modified precursors that do not provide alternative reaction sites that may interfere with a desired reaction of BsubOc formation.

[0080] Use of two reactants, A (a phthalonitrile derivative) and B (a dicyanonaphthalene derivative), provides a statistical mixture of up to four products (AAA, AAB, ABB, BBB), which can then be separated. Use of reactants A, B, and C (another phthalonitrile or a dicyanonaphthalene derivative), makes more possible product derivatives accessible, but generates up to eleven possible BsubOc products in a statistical mixture (AAA, BBB, CCC, AAB, AAC, ABB, ACC, BBC, CCB, and stereoisomers ABC and ACB). Such a mixture may be challenging to separate to its constituent components.

[0081] As an example BsubOcs, tetrafluorophthalonitrile and 2,3-dicyanonaphthalene may be reacted with a boron trichloride to produce a mixture of a peripherally fluorinated chloro boron subphthalocyanine (CI-F12BsubPc); chloro boron subnaphthalocyanine (CI-BsubNc); and two BsubOc hybrids, one comprising a single BsubNc-type lobe (CI-(F4A2)-(B1)-BsubOc) and the other comprising two BsubNc-type lobes (CI-(F4A1)-(B2)-BsubOc). To achieve a less fluorinated BsubOc, a 4,5-difluorophthalonitrile may be used instead of tetrafluorophthalonitrile. As an example of the concerns described above, it may be difficult to produce a BsubOc functionalized with peripheral cyano-groups in useful quantities: if present on the phthalonitrile or dicyanonaphthalene, these groups may also react during a macrocycle formation step.

[0082] Through process adjustments, synthesis methods for specific BsubOcs and derivatives may be designed to facilitate high yields product yields. Many otherwise-useful derivatives may not be economically viable without well-developed synthetic selectivity. A targeted product may be distinguished from side product(s), and purity thereby confirmed, through methods such as High Performance Liquid Chromatography (HPLC), which separates products and uses optical methods to identify species present in a sample and Nuclear Magnetic Resonance (NMR), which determines molecules present in a sample (carbon, hydrogen, fluorine, etc.) and thereby assists in identifying the molecular structures. Either method may assist to determine if a proper species is present in appropriate quantities.

[0083] Figs. 5 and 6 show graph 500 of a ¹⁹F NMR spectra for exemplary molecule 502 and graph 600 of a proton NMR spectra for the same exemplary molecule 602, according to an embodiment. Graphs 500 and 600 illustrate that the sampled materials have a single BsubNc- type lobe and two fluorinated BsubPc-type lobes. For example, the boron-fluorine bond measured in Fig. 5 shows the intensity that one fluorine provides, as the rightmost peak of graph 500. Depending on the relative intensity as well as the quantity and splitting of the other fluorine signals, it can be determined how many lobes of the molecule are fluorinated (in this case, formed from a tetrafluorophthalonitrile) or not (formed from a dicyanonaphthalene), as well as confirming how many fluorines are on each lobe.

[0084] Certain derivatives may be best suited for particular light-generating applications.

There may be various imposed requirements for light generating devices, such as performance requirements for: a red pixel in an RGB display; a white OLED in a lighting panel; and others. A particular derivative of an embodiment may be selected which meets such requirements. For example, a derivative of an embodiment that provides a deep red light (compliant with the SAE safety recommendations for a vehicular tail lamp), may be useful in automotive applications. In general lighting or display applications, long service hours (e.g. mean time between failure) may require that lifetime be a high priority. In such cases, derivatives with a lower likelihood of undesired interaction with host materials would be favoured. In battery-powered applications, electrical efficiency is a higher priority, favouring derivatives with the highest quantum yields.

The breadth of the molecular family of the embodiment permits selection of derivatives with designed characteristics to meet the needs of specific tasks.

Embodiments

[0085] Several embodiments are provided as any of a light emitting agent, a light emitting composition comprising one or more materials, or as a part of an organic electronic device such as an OLED. Here, a light emitting agent may be one or a combination of multiple BsubOc derivatives.

[0086] In an embodiment where the light emitting agent is part of a light emitting composition also comprising a host material, the light emitting agent may be selected based on its highest occupied molecular orbital (HOMO) and / or the lowest unoccupied molecular orbital (LUMO), which in such embodiments must be compatible with the energy levels of the host material. In the same and other embodiments, the light emitting agent (again, which may be a combination of various BsubOc molecules) may be selected based on its optical emission spectrum, which in such embodiments must enable the desired colour to be produced.

[0087] In an embodiment, the light emitting agent comprises a plurality of compounds. Each compound may exhibit emission spectra having peaks at different wavelengths. For example, implemented peaks may be selected and designed to provide a white OLED that is especially capable of illuminating red objects due to high light output in the red portion of the visible spectrum.

[0088] In an embodiment, the light emitting agent(s) are present in a composition at a concentration of at least about any of 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, or 50% by mass.

In some commercial applications the agent(s) are provided in a composition at a concentration of between about 0.1% and 5% by mass. In an embodiment, the agent(s) are present in a composition at a concentration of up to about any of 50, 60, 70, 80, 90, 95, 96, 97, 98, 99, or even 100% by mass. Therein, in such commercial applications the light emitting agent(s) may be provided in a composition at a concentration of approaching approximately 100% by mass.

In most cases, concentrations will be less than 10%, to ensure that excitons have a higher probability of forming on the TADF material or host material. This is preferred so that triplet excitons, the excitons formed in 75% of instances which cannot generate light when located on fluorescent light emitting agents such as BsubOcs, may be converted by the TADF material to singlet excitons, the excitons formed in 25% of instances which can generate light when located on fluorescent light emitting agents such as BsubOcs. Triplet excitons formed on or transferred to the fluorescent light emitting agent result in lost energy and may accelerate degradation, so it is desired for most excitons to form on the host or TADF material.

[0089] In an embodiment, the light emitting composition comprises a material capable of thermally assisted delayed fluorescence. The material capable of thermally assisted delayed fluorescence (TADF) converts triplets to singlets, and transfers energy to the light emitting agent. In an embodiment, the TADF material is TXO-PhCz, PXZ-TRZ or tri-PXZ-TRZ.

[0090] In an embodiment, the TADF material itself comprises multiple materials which can facilitate TADF through their interactions.

[0091] In an embodiment, the light emitting agent is selected based on the overlap between the emission spectrum of the TADF material and the absorption spectrum of the at least one BsubOc derivative, using the principle demonstrated by Nakanotani et al, Nature Communications, 2014, 5, Article 4016, which is here is incorporated by reference in full.

[0092] In an embodiment, the TADF material is present in the composition at a concentration of at least about any of 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, or 50% by mass. In some commercial applications the TADF material may be provided in a composition at a concentration of between approximately 5% and 50% by mass. In an embodiment, the material capable of thermally assisted delayed fluorescence is present in the composition at a concentration of up to about any of 50, 60, 70, 80, 90, 95, 96, 97, 98, or 99% by mass. In such commercial applications the TADF material may be provided in a composition at a concentration of between approximately 95% and 99.9% by mass. Commonly, concentrations will be less than 40%. Having more TADF material present in the film allows triplet excitons to be converted to singlets at a higher rate, but can harm other properties of the device if the TADF material is not a good transporter of electrical charge. [0093] In an embodiment, the light emitting composition comprises a host material. In an embodiment, the host material is CPB, mCP, or mCBP. In an embodiment, the host material comprises multiple materials forming a co-host.

[0094] In an embodiment, the host material is in the composition at a concentration of at least about any of 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, or 50% by mass. In an embodiment, the host material is present in the composition at a concentration of up to about any of 50, 60, 70, 80, 90, 95, 96, 97, 98, or 99% by mass. In most cases, concentrations may be greater than 50%, which provides good energy transport properties. The concentrations of the other two components influence a target concentration of the host material. Semantically, it will be seen that the host, as a “host”, will typically be at least 50% of the mass. In common commercial applications, the host is present at a concentration of approximately more than 75% of the mass and its concentration would not exceed 99.9%.

[0095] In an embodiment, the TADF material also functions as the host to form a two- component light emitting layer comprising only the light emitting agent and the TADF material.

In these cases, the concentration of the TADF material / host material will often be greater than 90%.

[0096] In another aspect, there is provided an organic light emitting diode (OLED) comprising at least one emissive material that includes or is the light emitting composition as described above in a light emitting layer.

[0097] In an embodiment, a boron sub-omni-phthalocyanine may be selected from any molecular variant shown in Figs. 2a-2g as would be known to those of skill in the art.

[0098] In an embodiment, the OLED may include an electron transport layer (ETL) and a hole transport layer (HTL). For example, referring to Fig. 4a, a cross-sectional diagram of layers in device 400 are shown, starting from its top cathode layer 402, followed by an ETL layer 404, followed by an Emissive Layer (EML) 406 having a host, a TADF dopant and a fluorescent dopant, followed by a hole transport layer (HTL) 408, followed by an anode layer 410, followed by substrate 412. In an embodiment, the ETL and HTL are n-type and p-type respectively. An encapsulating material (not shown), as known to those of skill in the art, may envelop device 400.

[0099] In an embodiment, an electron blocking layer and/or a hole blocking layer may be used on either side of the emissive material. The hole blocking layer, if any, is located between the electron transport layer and the emissive material, and the electron blocking layer, if any, is located between the hole transport layer and the emissive material. In an embodiment, the blocking layers are approximately between 45 and 60 nm thick, and may be varied, possibly considerably, as needed.

[00100] In an embodiment, charge injection layers are used between the anode and the rest of the device, and/or between the cathode and the rest of the device. In an embodiment, the injection layers are between approximately 5 nm and 25 nm thick, and may be varied, possibly considerably, as needed for a given application.

[00101] In an embodiment, the substrate is patterned or modified with an optical outcoupling layer. In a typical OLED device, emitted photons must pass through either the substrate (if bottom emission) or through the electrode and encapsulating layers (if top-emission) to escape the device. Photons emitted at too sharp an angle will be trapped and lost due to Total Internal Reflection (TIR), which places an upper limit on the external efficiency of the OLED device. An outcoupling layer modifies the optical properties of the interface to ensure that a larger proportion of the produced photons do not reflect and can escape the device.

[00102] In an embodiment, the light emitting agent uses dipole orientation to improve optical outcoupling. Photons are known to emit preferentially along the emissive molecule’s dipole. Ensuring that molecules are oriented with their dipoles pointed in the desired direction improves outcoupling and reduce the losses to reflectance, ultimately improving efficiency.

[00103] In an embodiment, the OLED produces light having a CIE coordinate at or near (0.708, 0.292), which is the BT.2020 standard for red, such that the OLED’s red output is not readily distinguishable from that of the BT.2020 red point to the untrained human eye. In an embodiment, the OLED produces light having a CIE coordinate at or near (0.64, 0.33), which is the Rec.709 standard for red, such that the OLED’s red output is not readily distinguishable from that of the Rec.709 red point to the untrained human eye.

[00104] In an embodiment, the OLED produces light having a CIE coordinate at or near (0.33, 0.33), which is the D65 white point. White OLEDs are useful in general lighting applications or as a light emitting panels used in a colour filtering-based display technology. In the latter application, colour filters are used on the subpixels to select only (typically) red, green, or blue light to pass through, but a white backlight producing all of the desired colours is required, typically via multiple light emitting agents and / or layers. [00105] In an embodiment, there is provided a method of producing an OLED comprising a substrate, applying an anode to the substrate, applying a hole transport layer, applying a light emitting layer, applying an electron transport layer, and applying a cathode. The light emitting layer comprises a light emitting composition as described above.

[00106] In an embodiment, there is provided a method of producing an OLED comprising preparing a substrate, applying a cathode to the substrate, applying an electron transport layer, applying a light emitting layer, applying a hole transport layer, applying an anode, and applying a barrier material. The light emitting layer comprises a light emitting composition comprising BsubOc as described above.

Examples

[00107] Following are descriptions of exemplary molecules and applications for an embodiment.

Example 1: Basic Synthesis and Prototype Device Fabrication

[00108] CI-(A2)-(B1)-BsubOc is synthesized by the reaction of phthalonitrile, dicyanonaphthalene and boron trichloride. Other materials for this OLED are purchased commercially. Quartz crystal microbalance sensors are placed in a physical vapour deposition system such that each sensor only has line-of-sight to its intended source, to avoid cross-talk that typically otherwise interferes with deposited layer thickness monitoring. Materials are loaded into crucibles which are then heated via electric current to achieve deposition, and the physical vapour deposition system is pumped to a low vacuum of approximately 5x1 OE ⁷ Torr.

[00109] Substrates are cleaned with acetone and kept in a dust-free environment until use. Substrates are loaded into the physical vapour deposition system without breaking vacuum via an airlock.

[00110] OLED devices may be fabricated on glass substrates, with exemplary dimensions of approximately 50.8 mm by 50.8 mm, with strips of indium tin oxide (ITO), which may be approximately 4 mm wide. TAPC is deposited, followed by a co-deposited layer of mCBP and BsubOc, followed by a layer of TmPyPB. With deposition of a perpendicular array of approximately 4 mm wide aluminum strips, the intersection with the indium tin oxide strips below results in each individual pixel having a surface area of approximately 16 mm². Each substrate contains approximately twenty pixels. Various OLED devices can be produced by varying the layer thicknesses and concentration ratios as shown in Table 1, which is achieved by varying the rates and durations of deposition processes. Data shown in Table 1 are approximate. Thicknesses of ITO, Al, and LiF are kept constant in these examples, and are not shown in Table 1.

Table 1: Architectures of Example Devices

[00111] In Table 1, each layer is separated by column. The approximate thickness and composition of each layer are denoted. The percentages indicate the concentration of the BsubOc component in the layer on a mass basis.

[00112] Different doping concentrations are incorporated in order to assess the potential of the BsubOc as dopants both alone and co-doped into OLEDs. For Device 4, the significant difference in deposition rate would ordinarily be difficult to achieve without a BsubOc deposition rate that is too small to detect or a mCBP deposition rate that causes excessive material use, if symmetric sensor placement is used. Instead, the BsubOc thickness monitoring sensor is placed much closer to the BsubOc source than the mCBP sensor is placed relative to its own source.

Example 2: OLED Characterization

[00113] The electroluminescent performance of each OLED produced, such as those presented in Example 1 , is tested in inert atmosphere immediately after fabrication and without encapsulation. Voltage, current and luminance data are collected concurrently for a range of applied voltages. Typical voltages are between approximately -1 V and 12 V.

[00114] Wavelength dependent emission spectra and luminance for individual pixels are measured using an HR2000+ High Resolution Spectrometer and integrating sphere. Driver voltage and device current are measured with a 2614B SourceMeter controlled by custom LabView software. CIE1931(x, y) co-ordinates for the produced light spectra are calculated according to the standard methods. Typical peak wavelength values for visible-spectrum OLEDs using BsubOc emitters range from approximately 590 nm to 650 nm; longer wavelengths are possible and desirable for infrared (IR) applications. Example 3: Incorporating a TADF-Capable Material

[00115] The light emitting composition may also include a material which is capable of thermally assisted delayed fluorescence. This material can improve efficiency by converting triplet states, which cannot relax radiatively in a fluorescence process, into singlet states, which can relax radiatively in a fluorescence process. Data shown in Table 2 are approximate. An example architecture using TXO-PhCz as the TADF-capable material is presented below, where each layer in the device is presented as a separate column:

Table 2: Architecture of Example Devices Incorporating a TADF Material

[00116] There are additional technical challenges to achieve three-material co-deposition over two-material co-deposition, as the rate of three thermal sources must be controlled in parallel. Deposition rates as low as approximately 0.01 Angstroms per second have been used for the BsubOc dopant. The process requires fine calibration of thermal sources in advance, as well as sufficient material to observe the continuous deposition of material until the rates are balanced in a manner that achieves the desired composition, at which point the substrate is exposed and device fabrication begins. All percent compositions presented are therefore not exact, and devices are considered successfully fabricated if the rate of deposition from each source (and resulting device composition) is maintained within predetermined tolerances.

[00117] The device architecture described in Table 2 is representative. For various BsubOc derivatives, other hosts besides mCBP, or other transport materials besides TAPC and TmPyPB, may be more appropriate, and more advanced OLED architectures known to the field may be applied.

[00118] Referring to Fig. 4b, an OLED with a BsubOc light emitting layer was produced according to this example design, and its measured CIE colour point of (0.71, 0.29) is shown in graph 414. This colour point allows for deeper red colour than is required by the Rec. 709 standard, and is very close to the red point required by the BT.2020 standard. The BT.2020 standard’s colour gamut is indicated by the triangular coloured region 416. Example 4: Using Various BsubOcs to Adjust Properties of OLED Devices

[00119] For an OLED developed for specific light specifications, it is beneficial to be able to finely adjust the properties of the emitter, as an alternative or in addition to adjusting the design of the OLED. OLED design parameters influence each other to a significant extent, as a change to any one layer can impact the electronic and optical performance of the other layers in the device, which can make optimization challenging. Slight adjustment of molecular properties presents another avenue for fine tuning.

[00120] For example, where an OLED is not efficiently transferring energy to the emitter molecule due to non-optimal energy level alignment, a BsubOc emitter can be replaced with a very similar BsubOc derivative which fine-tunes the energy levels without disrupting other properties of the device through changes such as altering the quantity of peripheral halogens. For example, CI-(F4A2)-(B1)-BsubOc, as referenced in the first row of Fig. 2a, could be replaced with CI-(F3A2)-(B1)-BsubOc, which would slightly impact energy levels. With the correct derivative, properties such as emitter alignment in film or the optical absorption spectrum can remain largely unchanged, which obviates the need for re-selection of other materials in the device. This possibility for fine-tuning arises due to the significant molecular orbital delocalization of the BsubOc molecule. Relative to the size of the molecule, a single changed substituent has less of an impact on the properties than is typical for a red fluorescent emitter.

[00121] In another example, a particular combination of host, TADF assistant, and fluorescent dopant may experience degradation as a result of Dexter energy transfer of triplets to the fluorescent dopant. This may be addressed without requiring changes to the host or assistant (which may not be a desirable to an OLED manufacturer) by functionalizing the first-attempted BsubOc molecule with non-aromatic “spacer groups”, which reduce Dexter transfer by increasing the distance between molecules. For example, F-(A2)-(gF₂B1)-BsubOc may be replaced by F-((CR₃)₂A2)-(gF₂B1)-BsubOc, which would significantly separate the molecule from its neighbours without contributing significantly to the aromatic structure and resulting energy levels.

[00122] In a further case where a BsubOc has been selected for its electronic and optical properties, but it is found that the dipoles are not aligning with the substrate for optimal light outcoupling, an axial substituent can be employed to change the orientability of the molecules in film. For example, CI-A1-B2-BsubOc could be replaced by PhO-A1-B2-BsubOc, where the axial substituent is a phenoxy group. As the axial substituent typically does not participate in the main delocalized molecular orbital, this does not significantly change the electronic and optical properties.

[00123] Fig. 7 shows two nearly identical OLED stacks 700a and 700b, where the same materials are used in all layers with the exception of the BsubOc fluorescent dopant, where the representative “BsubOc 1” in EML 706a is replaced with “BsubOc 2” in EML 706b without changes to other materials. Due to minor differences, re-optimization of layer thicknesses and doping concentrations may be beneficial. For example, the electron transport layers 704a and 704b of each device may vary in their specific implementation, and so onward for all the other elements, but these changes are much less drastic than selection of new materials. Alterations to the starting BsubOc can be achieved by employing precursors functionalized with the desired groups, or precursors which permit the addition of the desired groups in a subsequent synthetic step.

[00124] Fig. 7 shows OLED stacks 700a and 700b, each comprising the following materials: cathode 702a and 702b, comprising any of aluminum, silver, or other suitable bottom-emission OLED cathode material; ETL layer 704a and 704b, comprising any of Alq3, TPBi, TmPyPB, or other suitable electron transport materials; EML layer 706a and 706b, including a host of mCBP, CBP, mCP, or other suitable host material, a TADF dopant of TXO-PhCz, PXZ-TRZ, tri-PXZ- TRZ, or other suitable TADF-capable material, and a fluorescent dopant of any BsubOd and BsubOc2; HTL 708a and 708b, comprising any of NPB, TCTA, TAPC, or other suitable hole transport material(s); anode 710a and 710b, comprising any of ITO, ZnSnO, PEDOT:PSS, or other suitable bottom-emission OLED anode material(s); and substrate 712a, comprising any of glass, a polymer, an Si backplane, or other suitable bottom-emission OLED substrate material(s). If a top-emission architecture is used, the ordering of the elements is reversed, and other material choices may be impacted accordingly.

Example 5: Additional OLED Design Enhancements

[00125] In cases where high performance is required, the OLED device may include additional layers such as blocking layers and charge injection layers. These additional layers facilitate the concentration of the ideal amount of positive and negative charges, in the ideal distribution, throughout the device. Blocking layers hamper excitons from escaping the emissive layer after entering or forming within it. This may be done by choosing materials with HOMO or LUMO energy levels such that escape from the emissive layer into the blocking layer is thermodynamically unfavourable. An example of a blocking layer is TAPC, when interposed between an HTL and a host layer of m-CBP. Charge injection layers reduce the energy barrier between layers of dissimilar material. This may be done by choosing materials with HOMO or LUMO energy levels that are intermediate to those of the dissimilar materials. An example of an injection layer is NPB, when interposed between an anode layer and a host layer of m-CBP.

The OLED device may also incorporate a light outcoupling layer or patterning on its encapsulating surface, which suppresses total internal reflection and redirects photons to escape the device in greater quantities. BsubOc emitters are compatible with and benefit from these typical OLED performance enhancements already known to the field.

[00126] An example OLED design containing these features in support of a BsubOc emitter is shown below.

[00127] Referring to Fig. 8, an OLED architecture 800 using exemplary known enhancements is shown, for a general example of a bottom-emission OLED stack that integrates architecture enhancements to improve OLED performance. Inorganic and organic injection layers (814, 828 and 816, 826) provide intermediary energy level “steps” for charge carriers to move from anode 810 or cathode 802 into the device; hole or electron transport layers (808, 804) and their respective p- or n-type dopants facilitate the movement of holes or electrons towards the emissive layer 806; electron and hole blocking layers (824, 818) are selected to permit the flow of desired charge carriers towards the emissive layer while blocking “oncoming” charge carriers from escaping the emissive layer; host buffer zones (820, 822) may be used to precisely engineer the location of the light emissive layer so that recombination occurs where the light emitting agents are located or to achieve ideal optical resonance effects within the OLED stack; and the emissive layer 806 itself is designed to permit the movement of both charge carriers, the formation of excitons, and the energy transfer processes that lead to the emission of light. The OLED may also incorporate an outcoupling layer 830 and encapsulation to provide higher external quantum efficiency and lifetime respectively. In most cases, the layers are fabricated by physical vapour deposition.

[00128] The elements of stack 800 of Fig. 8 may comprise the following layered materials: an encapsulating material; aluminum, silver, or other suitable bottom-emission OLED cathode material 802; LiF, Liq, or other suitable inorganic injection material 814; Alq3 or other suitable organic injection layer 816; primarily Alq3, TPBi, TmPyPB, or other suitable electron transport material, and an electron transport n-dopant 804; BCP, DTBT, or other suitable hole blocking layer 818; the same host material as in element 814 or other suitable host buffer materials 820 and 822; a host of mCBP, CBP, mCP, or other suitable host material, a TADF dopant of TXO- PhCz, PXZ-TRZ, tri-PXZ-TRZ, or other suitable TADF-capable material, and a fluorescent dopant of any BsubOc 806; TCTA, or other suitable electron blocking material 824; primarily NPB, TCTA, TAPC, or other suitable hole transport material, and a hole transport p-dopant 808; m-MTDATA, CuPc, or other suitable organic injection material 826, MoOx, Cs2C03, or other suitable inorganic injection material 828; ITO, ZnSnO, PEDOT:PSS, or other suitable bottom- emission OLED anode material 810; glass, a polymer, an Si backplane, or other suitable bottom-emission OLED substrate material 812; patterned glass, or other suitable outcoupling material 830. If a top-emission architecture is used, the ordering of the elements is reversed, and other material choices may be implemented as necessary.

[00129] An OLED made according to this example may attain performance parameters of: brightness more than approximately 1000 cd/m², current density of less than approximately 10 mA/cm², CIE “X” coordinate of equal to or greater than BT.2020 red point’s value of 0.708, CIE Ύ” coordinate of equal to or less than BT.2020 red point’s value of 0.292, and a driving voltage of less than approximately 20 V, when using suitable industrial equipment and techniques.

Example 6: Multiple emission

[00130] Referring to Fig. 9, multiple light emitters, some or all of which may be BsubOcs, can be used in the same OLED device to produce light at several different peak wavelengths.

[00131] In Fig. 9, OLED stack 900 shows an architecture providing this colour output, where the different emitters are situated in various emissive layers 906 and 934 that produce a combined emission spectra which receives a contribution from the emission spectra of each emitter used. While Fig. 9 illustrates two emissive layers, it is noted that examples of five or more emissive layers in one device have been demonstrated in the field. The “buffer layer structure” 932, located between the emissive layers, may comprise many layers, which have the overall goal of balancing the movement of energy through the device for each emissive layer. A buffer layer structure would be located between each emissive layer.

[00132] With appropriately selected emitters wherein at least one emitter is a BsubOc, white light can be achieved. If multiple orange and/or red emitters are used together, a more continuous emission spectra may be achieved, resulting in improvements to the OLED’s colour rendering capability in the orange or red range in lighting applications. Multiple BsubOc emitters may also be used in the same emissive layer in some architectures, rather than distinct emissive layers as in Fig. 9. Such a BsubOc material comprising multiple BsubOc molecules according to an embodiment may produce light in the orange, red, and infrared range. Additionally, there may be many more emissive layers than the two shown in this example, where a buffer layer structure such as element 912 exists between successive emissive layers.

[00133] The layers in stack 900 may comprise the following layered materials: aluminum, silver, or other suitable bottom-emission OLED cathode material 902; LiF, Liq, or other suitable inorganic injection material 914; Alq3, TPBi, TmPyPB, or other suitable electron transport material 904; BCP, DTBT, or other suitable hole blocking layer 918; layer 906 comprising a host of mCBP, CBP, mCP, or other suitable host material, a TADF dopant of TXO-PhCz, PXZ-TRZ, tri-PXZ-TRZ, or other suitable TADF-capable material, and a fluorescent dopant of any BsubOc; layer 932 comprising appropriate materials and layers to facilitate an ideal distribution of charge; layer 934, providing a host of mCBP, CBP, mCP, or other suitable host material, a TADF dopant of TXO-PhCz, PXZ-TRZ, tri-PXZ-TRZ, or other suitable TADF-capable material, and a fluorescent dopant of any BsubOc; EBL 924, providing TCTA or other suitable electron blocking material; HTL 908, comprising primarily NPB, TCTA, TAPC, or other suitable hole transport material; inorganic injection layer 928, comprising MoOx, Cs2C03, or other suitable inorganic injection material; anode 910, comprising ITO, ZnSnO, PEDOT:PSS, or other suitable bottom- emission OLED anode material; and substrate 912, comprising glass, a polymer, an Si backplane, or other suitable bottom-emission OLED substrate material. If a top-emission architecture is used, the ordering of the elements is reversed, and other material choices may be implemented as necessary.

Example 7: Replacing a phosphor and its cavity resonance layer or filter

[00134] Due to the narrower emission of fluorescent materials in comparison to phosphorescent materials, OLEDs using a BsubOc emitter do not require as much colour filtration or as strict cavity resonance effects in order to achieve a deep red emission, such as a 630 nm emission peak and narrow full width half maximum of less than 40 nm, that is capable of providing a deep red light. In some cases, these filters can be eliminated entirely. A comparison of OLED device structures using a phosphor or BsubOc emitter to produce red light is presented in Fig. 10. The first OLED uses an emissive layer comprising BsubOc 1006a, and the second OLED uses a phosphorescent emissive layer 1006b with simple colour filtering layer 1036b. The colour filtering layer could be achieved with a dyed transparent compound, though other colour filtering methods exist for both top and bottom emission OLEDs, including cavity resonance effects. [00135] A notable advantage of avoiding colour filtering is that the device’s external quantum efficiency will increase if photons are not blocked. A preferred emitter only produces photons with the desired wavelengths, whereas a less preferred emitter, such as a phosphor, wastes energy by producing photons that must be blocked. For some red phosphorescent OLED emitters, half of all produced photons must be blocked in order to meet the BT.2020 requirement for red, while a BsubOc can meet the standard without use of a filter.

[00136] Fig. 10 shows exemplary stack 1000a and stack 1000b (which incorporates filters). In stack 1000a, its emissive layer 1006a uses a fluorescent dopant which does not require use of a colour filter to hit colour purity targets. In stack 1000b, its emissive layer 1006b uses a phosphorescent dopant which requires use of colour filter 1036b to match a colour purity target.

[00137] The layers in stacks 1000a and 1000b may comprise the following layered materials: cathode layer 1002a, 1002b, comprising aluminum, silver, or other suitable bottom-emission OLED cathode material; ETL layer 1004a, 1004b, comprising Alq3, TPBi, TmPyPB, or other suitable electron transport material; EML layer 1006a (for stack 1000a) comprising host of mCBP, CBP, mCP, or other suitable host material, TADF dopant of TXO-PhCz, PXZ-TRZ, tri- PXZ-TRZ, or other suitable TADF-capable material, and fluorescent dopant of any BsubOc;

EML layer 1006b (for stack 1000b) comprising host of mCBP, CBP, mCP, or other suitable host material, and phosphorescent dopant; HTL layer 1008a, 1008b, comprising NPB, TCTA, TAPC, or other suitable hole transport material; anode layer 1010a, 1010b, comprising ZnSnO, PEDOT:PSS, or other suitable bottom-emission OLED anode material; and substrate 1012a, 1012b, comprising glass, a polymer, an Si backplane, or other suitable bottom-emission OLED substrate material. In stack 1000b, there is additionally a colour filtering layer 1036b, comprising a transparent polymer filtering some visible wavelengths or other suitable colour filtering material or technique such as cavity resonance. If a top-emission architecture is used, the ordering of the elements is reversed, and other material choices may be implemented as necessary to permit light to escape from the top, rather than the bottom, of the device.

[00138] Although the disclosure has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the scope of the disclosure as outlined in the claims appended hereto.

Claims

Claims:

1. A light emitting composition incorporating a light emitting agent as set out by a formula following a molecular template:

wherein

A refers to a first set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, two, three, or four;

B refers to a second set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, two, three, or four;

M refers to a third set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, or two;

N refers to a fourth set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, two, three, or four; and in an absence of each of the first, second, third or fourth substituent, hydrogen is provided.

2. The light emitting composition of claim 1 , wherein any one or more of the first set of substituents A, the second set of substituents B, and the fourth set of substituents N comprises catechol.

3. The light emitting composition of claim 1, incorporated into an organic light emitting diode (OLED).

4. The light emitting composition of claim 3, wherein the OLED is provided in any of: an organic light emitting diode display; a lighting device; or a light signalling device.

5. A top-emission OLED structure comprising the light emitting composition of claim 3, wherein: the structure comprises: a transparent cathode; an emissive layer comprising a host and a BsubOc fluorescent dopant; and a reflective anode; and the structure further comprises one or more of: an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; a host buffer layer; an electron blocking layer; a hole transport layer containing a hole transport dopant; an organic injection material; an inorganic injection material; and a backplane or substrate.

6. The light emitting composition of claim 1, further incorporating a thermally assisted delayed fluorescence material.

7. The light emitting composition of claim 6, incorporated into an organic light emitting diode (OLED).

8. The light emitting composition of claim 7, wherein the OLED is provided in any of: an organic light emitting diode display; a lighting device; or a light signalling device.

9. A top-emission OLED structure comprising the light emitting composition of claim 7, wherein: the structure comprises a transparent cathode; an emissive layer comprising a host, a TADF dopant, and a BsubOc fluorescent dopant; and a reflective anode; and the structure further comprises one or more of: an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; a host buffer layer; an electron blocking layer; a hole transport layer containing a hole transport dopant; an organic injection material; an inorganic injection material; and a backplane or substrate.

10. The OLED of claim 7, wherein the OLED produces light near to the BT.2020 standard for red, with a CIE 1931 coordinate near to (0.708, 0.292).

11. The light emitting composition of claim 6, wherein the BsubOc is present at a concentration of between 0.1 and 5% by mass.

12. A light emitting composition incorporating a light emitting agent as set out by a formula following a molecular template:

wherein

M refers to a second set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, or two;

N refers to a third set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, two, three, or four; O refers to a fourth set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, or two;

P refers to a fifth set of substituents comprising any of F, Cl, Br, I, O-R, N-R₂, S-R, N0₂, SO3-R, S0₂-R, Se0₃-R, Se0₂-R, P0₃-R, P0₂-R, C-R₃, or R; and wherein n may be zero, one, two, three, or four;

X refers to a sixth set of substituents comprising any of F, Cl, Br, I, O, N, S, Se, P, phenyl, or C-R₃; and, if X is N or P, then both Y and Z are each R, phenyl, or Si-R₃, and if X is O or S or Se, then Y is R, phenyl, or Si-R₃ and Z is not present in any form, including hydrogen, and if X is a phenyl group, then that phenyl group may incorporate H, F, Cl, Br, I, O, N, or S substituents; and in an absence of each of the first, second, third, fourth, fifth, or sixth substituent, hydrogen is provided.

13. The light emitting composition of claim 12, wherein any one or more of the first set of substituents A, the third set of substituents N, and the fifth set of substituents P comprises catechol.

14. The light emitting composition of claim 12, incorporating an organic light emitting diode (OLED).

15. The light emitting composition of claim 14, wherein the OLED is provided in any of: an organic light emitting diode display; a lighting device; or a light signalling device.

16. A top-emission OLED structure comprising the light emitting composition of claim 14, wherein: the structure comprises: a transparent cathode; an emissive layer comprising a host and a BsubOc fluorescent dopant; and a reflective anode; and the structure further comprises one or more of: an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; a host buffer layer; an electron blocking layer; a hole transport layer containing a hole transport dopant; an organic injection material; an inorganic injection material; and a backplane or substrate.

17. The light emitting composition of claim 12, further comprising a thermally assisted delayed fluorescence material.

18. The light emitting composition of claim 17, incorporating an organic light emitting diode (OLED).

19. The light emitting composition of claim 17, wherein the OLED is provided in any of: an organic light emitting diode display; a lighting device; or a light signalling device.

20. A top-emission OLED structure comprising the light emitting composition of claim 17, wherein: the structure comprises: a transparent cathode; an emissive layer comprising a host, a TADF dopant and a BsubOc fluorescent dopant; and a reflective anode; and the structure further comprises one or more of: an inorganic injection layer; an organic injection layer; an electron transport layer containing an electron transport dopant; a hole blocking layer; a host buffer layer; an electron blocking layer; a hole transport layer containing a hole transport dopant; an organic injection material; an inorganic injection material; and a backplane or substrate.