Circularly polarized OLED emitting layer composition and light-emitting device having the same

Abstract

The present invention relates to an active light-emitting layer composition comprising a TADF molecule with TADF properties as a host material and a luminescent molecule with CP properties as a dopant. It also relates to a light-emitting device comprising the active light-emitting layer made of this composition.

Description

[Technical Field]

[0001] This invention relates to the technical field of compositions for organic light-emitting diodes (OLEDs) capable of emitting circularly polarized light, and also to light-emitting devices comprising such compositions. In particular, this invention relates to the technical field of compositions of OLED light-emitting layers or active layers. [Previous Technology]

[0002] Flat panel displays are ubiquitous in modern life. They are widely used in small and large devices, such as mobile phones, televisions, tablets, e-readers, virtual reality (VR) headsets, wearable smart devices, and other electronic products. These flat panel displays are mainly powered by liquid crystal displays (LCDs), such as twisted nematic LCDs (TN-LCDs) and super-twisted nematic LCDs (STN-LCDs). However, these devices inherently have low brightness and require strong backlighting, resulting in high power consumption.

[0003] The development of organic light-emitting diodes (OLEDs) offers promise for brighter and more energy-efficient devices. Indeed, OLEDs offer advantages such as low operating voltage and low power consumption, fast response, wide viewing angle, high brightness, and high contrast. Therefore, they are considered the most promising next-generation display technology.

[0004] Organic light-emitting diode (OLED) panels typically include a first electrode, a second electrode, and a functional structural layer located between the first and second electrodes. The functional structural layer includes a hole injection layer, a first hole transport layer, a second hole transport layer, an organic light-emitting layer, an electron transport layer, and an electron injection layer, which are sequentially stacked on the first electrode. Based on the properties of the light-emitting materials constituting the organic light-emitting layer, organic light-emitting diode (OLED) technology can be divided into two main categories: small molecule-based OLEDs and polymer-based OLEDs.

[0005] Significant progress has been made in the research of organic light-emitting diode (OLED) materials and devices. Recently, researchers have been studying the fabrication of circularly polarized organic light-emitting diodes (CP-OLEDs). Compared to non-polarized OLEDs, CP-OLEDs offer better contrast, which reduces the overall brightness required to achieve the same level of contrast as non-polarized OLEDs. Reduced overall brightness leads to lower power consumption.

[0006] To date, the most efficient strategy has been to use molecules capable of self-assembly at the supramolecular scale to amplify the polarization of the output light. For this purpose, a palmate liquid crystal passive filter can be used before the light source generated by another molecule. This can achieve a polarization rate of approximately several tens of percent. Another possibility is that liquid crystal-type luminescent polymers can use inherently palmate polymers or non-palmitate polymers doped with palmate molecules. This can achieve a high polarization rate.

[0007] For example, EP 1523533 B1 describes a composition comprising a palmate helical liquid crystal phase having a substantially fixed, temperature-independent helical pitch, which is composed of rod-shaped (calamitic) liquid crystal molecules having luminescent groups. This composition is in a mesophase, that is, a phase between a liquid phase and a crystalline solid phase.

[0008] Another example is EP 2877552 B2, which describes a composition made by mixing an electroluminescent polymer (e.g., a poly(arylene vinyl) derivative) with a non-racemic, non-luminescent dopant (e.g., a spiral hydrocarbon).

[0009] Both papers rely on the use of pure fluorescent emitters. Although the methods provided in these papers can exhibit a very high degree of circular polarization, the maximum quantum yield achievable by this system is theoretically limited to 25%. Therefore, the performance of CP-OLEDs fabricated through these methods is limited, thus hindering their use in large-scale applications.

[0010] The second method involves using a palmate luminescent entity in a conductive medium to directly generate circularly polarized light. This strategy is easier to implement, and its performance depends entirely on the inherent properties of the luminescent entity. It has been shown that it is difficult to find molecules that possess both high luminescence properties and high polarization rate. For example, lanthanide complexes have been used, which have a high light circular polarization rate of up to 75%, but exhibit poor chemical stability and very limited luminescence efficiency.

[0011] Other purely organic molecules are currently being studied. These organic molecules are of interest due to their high internal operating yield of approximately 100%. These molecules exhibit thermally activated delayed fluorescence (TADF) properties and are referred to below as TADF molecules. TADF is a process in which, when a TADF molecule is electrically or photoexcited, its excited state is in a certain equilibrium between singlet and triplet spin configurations, controlled by the energy level (ΔEST) between these two states. During this period, the equilibrium shifts towards the singlet state because deactivation through fluorescence occurs faster than phosphorescence from the triplet state (nanoseconds (ns) and microseconds (µs), respectively). Finally, there are two fluorescence processes: one occurs directly from the singlet state (prompt fluorescence, ns timescale), and the other is delayed due to the formation of the singlet-triple excited state equilibrium (delayed fluorescence, µs timescale). This balance is very important in, for example, organic light-emitting diodes, because they can produce 100% theoretical internal quantum efficiency, compared to the maximum of 25% for pure fluorescence as mentioned above.

[0012] Therefore, current methods for this type of molecule combine thermally activated delayed fluorescence (TRF) and circular polarization properties within a single molecule, which simplifies the fabrication process for CP-OLEDs. Designing such palmate TRF molecular emitters for CP-OLEDs is an extremely challenging task, as such compounds must combine chemical and photophysical properties to simultaneously achieve TRF and exhibit strong palmate optical properties (as well as a high racemization barrier deposited in a vacuum). Even though recent examples have shown that synergy between TRF and palmate optical properties can be easily obtained, adjusting one of the chemical / photophysical or palmate optical properties without interfering with the other appears to be a challenging task, and compromises can only be achieved.

[0013] However, it has been confirmed to date that the performance of this molecule is insufficient in terms of emission polarization rate. Indeed, the best molecule to date that simultaneously possesses thermally activated delayed fluorescence and circular polarization properties has achieved a polarization intensity of about 5 × 10–3 glum (Chen et al., Chem. Commun., 2020, 56, 9380–9383). [Summary of the Invention]

[0014] Therefore, an improved light-emitting layer is still needed in the field of organic light-emitting diode technology.

[0015] To this end, the present invention provides an active light-emitting layer composition comprising a thermally activated delayed fluorescence molecule having thermally activated delayed fluorescence properties as a host material and a light-emitting molecule having circular polarization properties as a dopant.

[0016] Therefore, the method of the present invention is a bimolecular strategy in the active light-emitting layer, which combines a first thermally activated delayed fluorescent molecule and a second light-emitting molecule. The first thermally activated delayed fluorescent molecule has a high conversion rate of converting electrical excitation into light energy and can transfer this energy to a second light-emitting molecule with circular polarization characteristics (hereinafter referred to as a circularly polarized molecule). The second light-emitting molecule serves as a dopant and as an emitter capable of emitting circularly polarized light with a high polarization rate.

[0017] The present invention differs from the conventional technology in that it uses thermally activated delayed fluorescence molecules without any circular polarization characteristics as the host molecules and uses circularly polarized molecules without any thermally activated delayed fluorescence characteristics as dopants.

[0018] This new method enables the light emitted by the composition to achieve a higher degree of polarization than that achievable with conventional techniques.

[0019] Other optional and non-restrictive features are as follows.

[0020] Thermal activated delayed fluorescent molecules can exhibit singlet and triplet energy levels, while the singlet energy level exhibited by circularly polarized molecules can be lower than that of thermally activated delayed fluorescent molecules.

[0021] Circularly polarized molecules may have absorption spectra, and thermally activated delayed fluorescent molecules may have emission spectra that overlap with the absorption spectra of circularly polarized molecules.

[0022] This composition exhibits a non-zero luminescence polarization as measured by the glum value. Preferably, the absolute value of |glum| is greater than 5 × 10⁻⁴, more preferably greater than 1 × 10⁻³, or even greater than 1 × 10⁻². This value is taken at the wavelength where the maximum luminescence intensity is measured.

[0023] This composition can exhibit a thermally activated delayed fluorescence quantum yield of more than 1%. Preferably, the thermally activated delayed fluorescence quantum yield is greater than 5%. More preferably, it is less than 50%. For example, any of the following figures can be used as a lower or higher range value: 10%, 20%, 30%, and 40%.

[0024] This composition can exhibit a quantum yield of 0.10 or higher. Preferably, the luminescent quantum yield is greater than 5%. More preferably, it is less than 100%. For example, any of the following figures can be used as a lower or higher range value: 10%, 15%, 20%, 30%, 50%, 75%, and 95%.

[0025] Circularly polarized molecules may be palmate molecules, such as helicene derivatives, helicenoid compounds, biaromatic systems, and molecules with planar palmateness (e.g., paracyclophane derivatives).

[0026] Circularly polarized molecules can be, for example, carbon[6]spiral hydrocarbon derivatives having the general formula of chemical formula 1 (hereinafter referred to as H6):

[0027] 〔Chemical Formula 1〕

[0028] In Formula 1, the linking chain B may be one of the following chemical groups shown in Formula 2:

[0029] 〔Chemical Formula 2〕

[0030] In chemical formula 1, B can also be a combination of two chemical groups in chemical formula 2, such as a combination of chemical group A and any other chemical group in chemical formula 2, preferably in the case where chemical group A is attached to a spiral hydrocarbon of chemical formula 1. In particular, B can be chemical group A of chemical formula 2 attached to chemical group F of chemical formula 2.

[0031] In chemical formula 1, R may be one of the following chemical groups described in chemical formula 3:

[0032] 〔Chemical Formula 3〕

[0033] More preferably, H6 has one of the following chemical formulas: 4, 5, 6, 7, 8, 9 and 10.

[0034] 〔Chemical Formula 4〕

[0035] 4,4'-(cyclohexane-2,15-dimethylbis(acetylene-2,1-dimethyl))dibenzylnitrile, hereinafter referred to as H6(CN)2.

[0036] 〔Chemical Formula 5〕

[0037] 4,4'-(cyclohexane-2,15-dimethylbis(acetylene-2,1-dimethyl))dipyridine, hereinafter referred to as H6(Py)2.

[0038] 〔Chemical Formula 6〕

[0039] 4,4'-(cyclohexaphenyl-2,15-dimethylbis(acetylene-2,1-dimethyl))diphenylamine, hereinafter referred to as H6(NH2)2.

[0040] 〔Chemical Formula 7〕

[0041] 4,4'-(cyclohexabenzene-2,15-dimethylbis(acetylene-2,1-dimethyl))bis(N,N-dimethylaniline), hereinafter referred to as H6(NMe2)2.

[0042] 〔Chemical Formula 8〕

[0043] 4,4'-(cyclohexaphenyl-2,15-dimethylbis(acetylene-2,1-diyl))bis(trimethylsilane), hereinafter referred to as H6(TMS)2.

[0044] 〔Chemical Formula 9〕

[0045] 4,4'-(cyclohexane-2,15-dimethylbis(acetylene-2,1-dimethyl))bis(N-hexyl-1,8-naphthodimethylimine), hereinafter referred to as H6(NPh)2.

[0046] 〔Chemical Formula 10〕

[0047] 4,4'-(cyclohexane-2,15-dimethylbis(acetylene-2,1-dimethyl))di(2,5-N-octyl-3,6-di-2-thienyl-pyrrole[3,4-c]pyrrole-1,4-dione), hereinafter referred to as H6(DPP)2.

[0048] H6 can display either P configuration or M configuration.

[0049] Thermally activated delayed fluorescence molecules may be palmite molecules. In particular, thermally activated delayed fluorescence molecules may have one of the following chemical formulas 11, 12 and 13.

[0050] 〔Chemical Formula 11〕

[0051] 9,9'-(sulfonylbis(4,1-epenylphenyl))bis(3,6-bis(tributyl)-9H-carbazole), hereinafter referred to as dt-BuCbzSulfone.

[0052] 〔Chemical Formula 12〕

[0053] 9-(4-(4,6-diphenyl-1,3,5-tris(2-yl)phenyl)-1,3,6,8-tetramethyl-9H-carbazole, hereinafter referred to as Cbz-TRZ2.

[0054] 〔Chemical Formula 13〕

[0055] 2,4,5,6-Tetra(9H-carbazole-9-yl)isophthalonitrile, hereinafter referred to as 4-CbzIPN.

[0056] The active luminescent layer composition may have one of the following combinations of thermally activated delayed fluorescent molecules and circularly polarized molecules: dt-BuCbzSulfone and H6(CN)2; Cbz-TRZ2 and H6(NPh)2; and 4-CbzIPN and H6(DPP)2.

[0057] However, the present invention is not limited to these combinations, and may also be any other combination: dt-BuCbzSulfone with H6(NPh)2 or H6(DPP)2; Cbz-TRZ2 with H6(CN)2 or H6(DPP)2; 4-CbzIPN with H6(CN)2 or H6(NPh)2.

[0058] The amount of circularly polarized molecules, measured by the mole number of thermally activated delayed fluorescein molecules, can be 1 to 30%, preferably 1 to 20%, 1 to 10% or 1 to 5%.

[0059] This composition may further include a conductive dielectric to transfer charge through the light-emitting layer. In this case, the amount of thermally activated delayed fluorescent molecules is preferably 1 to 30%, more preferably 1 to 20%, 1 to 10%, or 1 to 5% in terms of the mole number of the conductive dielectric.

[0060] The total amount of thermally activated delayed fluorescent molecules and circularly polarized molecules is preferably 1% to 40% and 5% to 30% of the total weight of the composition, respectively.

[0061] The present invention also provides a light-emitting device having an active light-emitting layer made of the active light-emitting layer composition described above. The light-emitting device may be an organic light-emitting diode display device. [Implementation Method]

[0070] The present invention will be further described in detail below with reference to Figures 1 to 7. Throughout the specification, when there is a difference between the name of a compound and its developed structure, the developed structure shall be given priority (unless otherwise stated, its configuration shall not be considered).

[0071] The principle of this invention is based on the energy transfer that occurs between thermally activated delayed fluorescent molecules and circularly polarized molecules; the thermally activated delayed fluorescent molecules are the main body and the circularly polarized molecules are the emitters, ultimately emitting circularly polarized light.

[0072] More precisely, as shown in Figure 1, when a thermally activated delayed fluorescent molecule is electrically or photoexcited, its excited state will be in a certain equilibrium between the singlet state S1 and the triplet state T1 spin configuration (through intersystem crossing and reverse intersystem crossing processes), controlled by the energy level ΔEST between these two states. During this period, the equilibrium shifts towards the singlet state S1 because its deactivation through fluorescence occurs faster than phosphorescence from the triplet state T1 (at rates on the order of ns and µs, respectively). Finally, there are two fluorescence processes: one occurs directly from the singlet state S1 (instantaneous fluorescence, ns timescale), and the other is delayed due to the formation of the singlet-triple excited state equilibrium (delayed fluorescence, µs timescale). This equilibrium is very important in, for example, organic light-emitting diodes, because it can produce 100% theoretical internal quantum efficiency, compared to the maximum theoretical internal quantum efficiency of 25% for pure fluorescent emitters.

[0073] The inventors have discovered that by using luminescent molecules whose excited state S'1 is lower than the singlet and triplet states of thermally activated delayed fluorescent molecules to dope solid films of thermally activated delayed fluorescent molecules, deactivation may occur through a different pathway than instantaneous and delayed fluorescence; that is, energy transfer from the singlet state S1 of the thermally activated delayed fluorescent molecule to the excited state S'1 of the luminescent molecule with the lowest energy. The luminescent molecule eventually emits light when it returns to its ground state S'0. In this case, the luminescent molecule exhibits circular polarization characteristics; for example, when it is a palmate molecule, it emits circularly polarized light when the thermally activated delayed fluorescent molecule is exposed to light and / or electrically excited.

[0074] "Doping ratio" refers to the proportion of the dopant relative to the thermally activated delayed phosphor in the composition, expressed in moles. This bimolecular system can also be placed in an organic medium to form a ternary active layer (here, "doping ratio" is based on the proportion of the palmar emitter relative to the thermally activated delayed phosphor, expressed in moles).

[0075] To ensure more efficient energy transfer, the emission spectrum of thermally activated delayed fluorescent molecules should overlap with the absorption spectrum of circularly polarized molecules. Furthermore, in the emitting layer of an organic light-emitting diode, the proportion of circularly polarized molecules relative to thermally activated delayed fluorescent molecules should be as low as possible to avoid direct carrier trapping. This is why they are used as dopants rather than as the main component of the composition. However, it should not be too low to ensure sufficient energy transfer and residual thermally activated delayed fluorescence emission. Therefore, the optimal ratio of circularly polarized molecules to thermally activated delayed fluorescent molecules can be varied, and those skilled in the art can optimize the ratio for different combinations of thermally activated delayed fluorescent molecules and circularly polarized molecules.

[0076] Method

[0077] NMR spectral measurement

[0078] 1H and 13C NMR spectra were recorded at room temperature using an AVANCE III 400 BRUKER or AVANCE I 500 BRUKER. Chemical shifts δ are expressed in ppm, and coupling constants J are expressed in Hz. The chemical shifts in the 1H NMR spectra are relative to residual protium in the deuterated solvent (δ = 7.26 ppm, CDCl3). The 13C shifts are referenced to the CDCl3 peak at δ = 77.16 ppm.

[0079] Mass Spectrometry Measurement

[0080] High-resolution mass spectrometry (HR-MS) was performed on a Bruker MaXis 4G spectrometer using CH2Cl2 as solvent via ASAP (+ or -) or ESI and MALDI at CRMPO. The experimental mass and computational mass were determined by considering the mass of the electrons.

[0081] UV Spectral Measurement

[0082] The ultraviolet-visible (UV-vis, M-1 cm-1) absorption spectrum was recorded using a UV-2401PC Shimadzu spectrophotometer.

[0083] Fluorescence Spectroscopy Measurement

[0084] The fluorescence spectrum was recorded using an FL 920 Edinburgh fluorimeter.

[0085] Measurement of Fluorescent Quantum Yield

[0086] The fluorescence quantum yield in the diluted solution (in dichloromethane) was calculated using the following mathematical formula 1; where the subscripts "ST" and "X" represent "standard" and "sample," respectively, Φ is the fluorescence quantum yield, Grad is the gradient of the integral fluorescence intensity versus absorbance graph, and η is the refractive index of the solvent. The references for the fluorescence quantum yield used here are quinine sulfate and rhodamine 6G in 0.5 M sulfuric acid (excitation of the reference and sample compounds was performed at the same wavelength).

[0087] 〔Mathematical Formula 1〕

[0088] The fluorescence quantum yield in solid state was calculated using the following mathematical formula 2; where "R" and "X" represent the reference and sample, respectively. A(λ) is the absorbance at the excitation wavelength λ, n is the refractive index, and D is the integrated intensity. The luminescence quantum yield relative to rose red 6G in ethanol (ΦR = 0.91) was measured. Excitation of the reference and sample compounds was performed at the same wavelength.

[0089] 〔Mathematical Formula 2〕

[0090] Measurement of quantum yield of thermally activated delayed fluorescence

[0091] The thermally activated delayed fluorescence quantum yield was determined by using the fluorescence quantum yield determined under aerobic (ΦOx) and anaerobic (ΦAr) conditions, assuming that the delayed fluorescence under aerobic conditions is negligible (see Formula 3).

[0092] 〔Mathematical Formula 3〕

[0093] ΦOx and ΦAr were determined by using the total photoluminescence quantum efficiency and measured using a Hamamatsu C9920-03 integrating sphere.

[0094] Measurement of luminescence asymmetry factor

[0095] The luminescence dissymmetry factor glum represents circular polarization. It is calculated by mathematical formula 4, where IL and IR represent the intensity of left-handed and right-handed polarized light, respectively.

[0096] 〔Mathematical Formula 4〕

[0097] The glum value ranges from -2 to +2, where a negative value indicates right-handed circular polarization and a positive value indicates left-handed circular polarization. A value of 0 indicates no circular polarization, while an absolute value of 2 indicates fully circularly polarized light.

[0098] These measurements were performed using a CPL spectrometer (JASCO Company). The sample was dissolved in dichloromethane and excited using a 90° geometry with a Xenon ozone-free lamp 150 W LS. The following parameters were used: emission slit width ≈ 2 mm, integration time = 4 sec, scan rate = 50 nm / min, accumulation = 5. The sample was excited at 350 nm. Further details are described in Abbate et al., 2016 [1].

[0099] Example 1: 2,15-bisethynylcyclohexaphenylH6(H)2 and 4,4'-(cyclohexaphenyl-2,15-diylbis(ethynyl-2,1-diyl))bis(trimethylalkane)H6(TMS)2

[0100] P-H6(H)2 and H6(TMS)2 of chemical formula 14 were prepared by following the strategy previously reported by Crassous, J et al. (2018) [2].

[0101] 〔Chemical Formula 14〕

[0102] Example 2: 4,4'-(cyclohexabenzyl-2,15-dimethylbis(acetyl-2,1-dimethyl))dibenzylnitrile H6(CN)2

[0103] P-H6(CN)2 was synthesized as shown in Chemical Formula 15 below. First, P-H6(H)2 (50 mg, 0.13 mmol) and 4-bromobenzyl nitrile (71 mg, 0.39 mmol) were placed in an oven-dried 25 mL flask under argon atmosphere. Next, 4 mL of dried toluene and 1 mL of dried triethylamine (Et3N) were added, and the resulting solution was deoxygenated by purging with argon for 1 hour. Tetra(triphenylphosphine)palladium(O) (Pd(PPh3)4) (15 mg, 0.013 mmol) and iodide(I) (CuI) (4.9 mg, 0.026 mmol) were added, and the solution was refluxed for 3 hours. After cooling to room temperature, the solution was passed through a short silica plug (dichloromethane, CH2Cl2). The mixed crude products were further purified by silicon column chromatography (8 / 2 heptane / CH2Cl2 elution system) to produce a yellow solid P-H6(CN)2 (63.9 mg, 85%).

[0104] 〔Chemical Formula 15〕

[0105] ¹H NMR (300 MHz, dichloromethane-d²) δ 8.19 – 8.07 (m, 6H), 8.04 – 7.99 (d, J = 8.6 Hz, 2H), 7.90 – 7.88 (s, 1H), 7.87 – 7.83 (dd, J = 3.1, 2.0 Hz, 3H), 7.69 – 7.67 (d, J = 1.3 Hz, 2H), 7.67 – 7.63 (d, J = 1.3 Hz, 2H), 7.47 – 7.44 (d, J = 1.2 Hz, 2H), 7.44 – 7.42 (d, J = 1.6 Hz, 3H), 7.41 – 7.39 (d, J = 1.5 Hz, 1H).

[0106] 13C NMR (75 MHz, dichloromethane-d2) δ 133.6, 133.2, 132.2, 132.1, 132.11, 132.1 – 132.0, 132.0 – 131.9, 131.8 – 131.7, 129.2 – 128.9, 128.2 – 128.0, 127.9 – 127.8, 127.9 – 127.8, 127.8 – 127.7, 127.7 – 127.6, 127.5 – 127.4, 127.4 – 127.3, 127.0 – 126.9, 124.0 – 123.6, 118.5 – 118.4, 118.4 – 118.3, 111.5 – 111.2, 94.3 – 93.1, 88.2 – 86.0.

[0107] HR-MS Ultraflex III, MALDI, 370 °C; ion [M]+., C44H22N2, calculated m / z value 578.17775, experimental m / z value 578.182 (Δ=7 ppm).

[0108] Example 3: 4,4'-(cyclohexaphenyl-2,15-diylbis(acetyl-2,1-diyl))dipyridine H6(Py)2

[0109] P-H6(Py)2 was synthesized as shown in Chemical Formula 16 below. A mixture of P-H6(H)2 (50 mg, 0.13 mmol) and 4-bromopyridine hydrochloride (75.8 mg, 0.39 mmol) was placed in an oven-dried 25 mL flask under argon atmosphere. Then, 5 mL of dry propylamine was added, and the resulting solution was deoxygenated by purging with argon for 1 hour. Pd(PPh3)4 (15 mg, 0.013 mmol) and CuI (4.9 mg, 0.026 mmol) were added, and the solution was refluxed for 3 hours. After cooling to room temperature, the solution was passed through a short silicon stopper (CH2Cl2). The crude mixture was further purified by silicon column chromatography (5 / 5 heptane / CH2Cl2 precipitation system) to produce a yellow solid, P-H6(Py)2 (44.8 mg, 65%).

[0110] 〔Chemical Formula 16〕

[0111] ¹H NMR (400 MHz, dichloromethane-d²) δ 8.61 – 8.59 (d, J = 1.7 Hz, 2H), 8.59 – 8.56 (d, J = 1.7 Hz, 2H), 8.16 – 8.12 (d, J = 8.2 Hz, 2H), 8.12 – 8.10 (d, J = 1.6 Hz, 2H), 8.10 – 8.06 (d, J = 2.0 Hz, 2H), 8.05 – 8.02 (s, 1H), 8.02 – 8.00 (s, 1H), 7.91 – 7.89 (s, 1H), 7.88 – 7.87 (s, 1H), 7.87 – 7.83 (m, 2H), 7.44 – 7.43 (d,J= 1.6 Hz, 1H), 7.42 – 7.41 (d,J= 1.6 Hz, 1H), 7.24 – 7.22 (d,J= 1.7 Hz, 2H), 7.22 – 7.20 (d,J= 1.6 Hz, 2H).

[0112] 13C NMR (101 MHz, dichloromethane-d2) δ 149.9, 149.6, 133.6, 133.3, 132.4, 132.2, 132.2, 132.1, 132.0, 131.8, 131.6, 131.0, 129.1, 129.0, 127.9, 127.9, 127.9, 127.9, 127.9, 127.8, 127.7, 127.6, 127.5, 127.5, 127.4, 127.4, 127.1, 126.8, 125.5, 124.9, 124.0, 123.4, 118.4, 118.0, 94.3, 92.0, 87.1, 84.2.

[0113] HR-MS Ultraflex III, MALDI, 370 °C; ion [M+H]+., C40H23N2, calculated m / z value 531.18557, experimental m / z value 531.182 (Δ=7 ppm).

[0114] Example 4: 4,4'-(cyclohexaphenyl-2,15-dimethylbis(acetyl-2,1-dimethyl))diphenylamine H6(NH2)2

[0115] P-H6(NH2)2 was synthesized as shown in Chemical Formula 17 below. P-H6(H)2 (50 mg, 0.13 mmol) and 4-iodoaniline (126 mg, 0.575 mmol) were placed in an oven-dried 25 mL flask under argon atmosphere. Then, 5 mL of dried propylamine was added, and the resulting solution was deoxygenated by purging with argon for 1 hour. Pd(PPh3)4 (15 mg, 0.013 mmol) and CuI (4.9 mg, 0.026 mmol) were added, and the solution was refluxed for 3 hours. After cooling to room temperature, the solution was passed through a short silicon stopper (CH2Cl2). The mixed crude product was further purified by silicon column chromatography (5 / 5 heptane / CH2Cl2 dissolution system) to produce a yellow solid, P-H6(NH2)2 (47.2 mg, 65%).

[0116] ¹H NMR (400 MHz, dichloromethane-d²) δ 8.10 – 7.94 (m, 8H), 7.85 – 7.78 (d, J = 8.3 Hz, 2H), 7.75 – 7.72 (m, 2H), 7.37 – 7.35 (d, J = 1.6 Hz, 1H), 7.34 – 7.33 (d, J = 1.6 Hz, 1H), 7.14 – 7.13 (d, J = 2.0 Hz, 2H), 7.12 – 7.11 (d, J = 2.0 Hz, 2H), 6.64 – 6.62 (d, J = 2.0 Hz, 2H), 6.62 – 6.59 (d, J = 2.0 Hz, 2H). Hz, 2H), 3.93 – 3.85 (s, 4H).

[0117] 13C NMR (101 MHz, dichloromethane-d2) δ 148.1, 146.2, 133.6, 133.3, 132.9, 132.7, 132.2, 131.8, 131.6, 131.4, 131.3, 131.1, 129.6, 129.3, 128.2, 127.9, 127.8, 127.7, 127.7, 127.6, 127.5, 127.4, 127.3, 127.2, 127.1, 126.9, 124.5, 123.6, 120.7, 119.9, 115.3 ,114.3, 112.9, 111.9, 90.4, 88.7, 88.1, 86.7.

[0118] HR-MS Ultraflex III, MALDI, 370°C; ion [M]+., C42 H26N2, calculated m / z value 558.20905, experimental m / z value 558.207 (Δ=4 ppm).

[0119] Example 5: 4,4'-(cyclohexaphenyl-2,15-diylbis(acetyl-2,1-diyl))bis(N,N-dimethylaniline)H6(NMe2)2

[0120] P-H6(NMe2)2 was synthesized from H6(NH2)2 in Example 4 as shown in Chemical Formula 17 below. Formaldehyde (0.04 mL, 0.13 mmol) was added dropwise to a solution of P-H6(NH2)2 (30 mg, 0.054 mmol) dissolved in 5 mL of tetrahydrofuran (THF) in a round-bottom flask. The mixture was stirred at room temperature under argon for 15 minutes. Then, sodium cyanoborohydride (NaBH3CN) (34 mg, 0.54 mmol) was directly introduced into the solution. The mixture was stirred a second time at room temperature for 15 minutes. The reaction was terminated by adding acetic acid (1 mL), and the solution was stirred at room temperature for 2 hours. After adding water and dichloromethane (25 mL each), the organic layer was separated, and the aqueous layer was extracted with dichloromethane. All organic layers were collected, dried over MgSO4, and the solvent was evaporated. The crude product was purified using a silicon plug and washed with dichloromethane to obtain the desired product P-H6(NMe2)2 (14.9 mg, 45%) as a yellow solid.

[0121] 〔Chemical Formula 17〕

[0122] ¹H NMR (400 MHz, dichloromethane-d²) δ 8.16–7.97 (m, 8H), 7.91–7.81 (d, J = 8.3 Hz, 2H), 7.81 – 7.74 (d, J = 1.5 Hz, 2H), 7.43 – 7.34 (dd, J = 8.2, 1.6 Hz, 2H), 7.26 – 7.24 (d, J = 2.1 Hz, 2H), 7.23 – 7.21 (d, J = 2.0 Hz, 2H), 6.73 – 6.69 (d, J = 2.1 Hz, 2H), 6.69 – 6.66 (s, 2H), 3.20 – 2.52 (s, 12H).

[0123] 13C NMR (126 MHz, dichloromethane-d2) δ 150.6, 149.5, 133.4, 133.1, 132.5, 132.3, 131.9, 131.7, 131.3, 131.2, 131.0, 130.7, 129.5, 129.3, 127.9, 127.8, 127.6, 127.6, 127.5, 127.4, 127.3 – 127.2 (d, J = 3.7 Hz), 127.2, 127.1, 126.8, 126.7, 124.1, 123.8, 120.6, 120.3, 112.7, 110.6, 110.5, 109.4, 90.4, 89.1, 88.2, 86.4, 40.5, 39.2.

[0124] HR-MS Ultraflex III, ESI, 370°C; ion [M+H]+., C46H35N2, calculated m / z value 615.27947, experimental m / z value 615.2796 (Δ=0 ppm).

[0125] Example 6

[0126] The measurement results of the luminescence quantum yield and luminescence asymmetry factor of Examples 1 to 5 above in dichloromethane at 298 K are summarized in Table 1 below (in the table, "yEx" means "y×10x").

[0127] 〔Table 1〕 compound Φ X (%) |g lum | λ(nm) H6(TMS)2 6 1.1E-2 421 H6(CN)2 9 2.7E-2 426 H6(Py)2 6 2.5E-2 429 H6(NH2)2 16 2.5E-2 430 H6(NMe2)2 41 5.2E-3 500

[0128] Example 7

[0129] The present invention is provided herein. In this example, the active light-emitting layer composition comprises dt-BuCbzSulfone as a thermally activated delayed fluorescence molecule and H6(CN)2 as a circularly polarized molecule. The thermally activated delayed fluorescence molecule dt-BuCbzSulfone was developed by Adachi et al. [3] in 2012, while H6(CN)2 was first synthesized and developed by the applicant.

[0130] The singlet energy level of H6(CN)2 is 2.99 eV at 415 nm and 2.92 eV at 425 nm. The photophysical and palmar optical properties of H6(CN)2 are shown in Figures 2 and 3.

[0131] Tables 2 and 3 below show the normalized absorbance and normalized emission values ​​corresponding to those in Figure 2, which are between 250 nm and 600 nm. In Figure 2, normalized absorbance is represented by a dashed line, and normalized emission is represented by a solid line. The highest peak is normalized to 1, and the others are proportional to it.

[0132] 〔Table 2〕 λ(nm) I(au) λ(nm) I(au) λ(nm) I(au) λ(nm) I(au) 250 0.553 350 0.423 450 0.004 550 0.000 255 0.556 355 0.392 455 0.005 555 0.000 260 0.599 360 0.355 460 0.004 560 0.000 265 0.678 365 0.316 465 0.003 565 0.000 270 0.733 370 0.267 470 0.001 570 0.000 275 0.697 375 0.239 475 0.000 575 0.000 280 0.672 380 0.223 480 0.000 580 0.000 285 0.687 385 0.186 485 0.000 585 0.000 290 0.727 390 0.127 490 0.000 590 0.000 295 0.784 395 0.072 495 0.000 595 0.000 300 0.890 400 0.046 500 0.000 600 0.000 305 1.000 405 0.026 505 0.001 310 0.955 410 0.011 510 0.001 315 0.846 415 0.009 515 0.000 320 0.716 420 0.011 520 0.001 325 0.637 425 0.012 525 0.001 330 0.567 430 0.005 530 0.000 335 0.510 435 0.001 535 0.000 340 0.475 440 0.001 540 0.000 345 0.452 445 0.003 545 0.000

[0133] 〔Table 3〕 λ (nm) I (a.u.) λ (nm) I (a.u.) λ (nm) I (a.u.) λ (nm) I (a.u.) ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ 0.012 412 0.038 462 0.549 512 0.088 562 0.012 414 0.065 464 0.485 514 0.082 564 0.011 416 0.117 466 0.428 516 0.078 566 0.010 418 0.223 468 0.389 518 0.073 568 0.009 420 0.413 470 0.355 520 0.068 570 0.009 422 0.663 472 0.334 522 0.064 572 0.008 424 0.895 474 0.317 524 0.059 574 0.007 426 1.000 476 0.305 526 0.054 576 0.006 428 0.994 478 0.300 528 0.050 578 0.006 430 0.916 480 0.294 530 0.045 580 0.005 432 0.803 482 0.290 532 0.040 582 0.005 434 0.699 484 0.282 534 0.037 584 0.005 436 0.604 486 0.271 536 0.033 586 0.004 438 0.528 488 0.252 538 0.031 588 0.004 440 0.478 490 0.232 540 0.028 590 0.004 442 0.460 492 0.212 542 0.025 592 0.004 444 0.479 494 0.189 544 0.023 594 0.003 446 0.534 496 0.172 546 0.021 596 0.003 448 0.586 498 0.155 548 0.020 598 0.003 450 0.656 500 0.140 550 0.018 600 0.003

[0134] Table 4 below corresponds to Figure 3 and reveals the intensity difference ΔI between the left-handed and right-handed luminescence values ​​of P-H6(CN)2 (solid line) and M-H6(CN)2 (dashed line) between 250 nm and 600 nm (in the table, "yEx" represents "y×10x"). It can be seen that the difference between the normalized left-handed and right-handed luminescence of H6(CN)2 in the P and M configurations is almost symmetrical through the line segment at coordinate 0. Furthermore, since the normalization is based on the highest peak of the total emission spectrum being normalized to a value of 2 (different from Figure 2), the value of ΔI at the wavelength of the highest total intensity peak is defined as glum. It is found that the glum value of H6(CN)2 is about 3×10–2; however, it does not have thermally activated delayed fluorescence characteristics.

[0135] 〔Table 4〕 λ(nm) ΔI (au) λ(nm) ΔI (au) P-H6(CN)2 M-H6(CN)2 P-H6(CN)2 M-H6(CN)2 380 -2.27E-04 -- 495 3.55E-03 -3.65E-03 385 -2.23E-04 -5.90E-04 500 2.57E-03 -2.96E-03 390 -1.93E-04 -5.82E-04 505 1.67E-03 -2.35E-03 395 -1.37E-04 -6.20E-04 510 1.40E-03 -1.99E-03 400 -9.41E-05 -8.07E-04 515 8.96E-04 -1.69E-03 405 2.23E-04 -9.93E-04 520 7.12E-04 -1.65E-03 410 1.41E-03 -2.39E-03 525 5.63E-04 -1.08E-03 415 5.72E-03 -6.58E-03 530 2.85E-04 -1.26E-03 420 1.44E-02 -1.47E-02 535 2.34E-04 -8.30E-04 425 2.29E-02 -2.36E-02 540 1.16E-04 -8.40E-04 430 2.74E-02 -2.77E-02 545 7.35E-05 -8.60E-04 435 2.41E-02 -2.40E-02 550 -6.46E-05 -8.11E-04 440 1.85E-02 -1.92E-02 555 -8.35E-05 -7.51E-04 445 1.56E-02 -1.56E-02 560 -1.22E-04 -6.27E-04 450 1.62E-02 -1.69E-02 565 -1.73E-04 -7.16E-04 455 1.69E-02 -1.82E-02 570 -1.59E-04 -6.41E-04 460 1.56E-02 -1.68E-02 575 -1.49E-04 -5.58E-04 465 1.32E-02 -1.30E-02 580 -2.15E-04 -6.59E-04 470 9.60E-03 -1.02E-02 585 -1.74E-04 -5.70E-04 475 7.36E-03 -8.28E-03 590 -2.01E-04 -5.80E-04 480 6.33E-03 -6.73E-03 595 -2.19E-04 -5.89E-04 485 5.25E-03 -5.95E-03 600 -1.96E-04 -5.59E-04 490 4.34E-03 -4.96E-03

[0136] To test combinations of dt-BuCbzSulfone doped with H6(CN)2, four doping ratios (1, 5, 10, and 20 mol.%) of the total amount of dt-BuCbzSulfone were prepared and spin-coated onto a substrate to form solid films. Figure 4 provides luminescence measurements from 370 nm to 650 nm, and the measurements are further disclosed in Table 5 below (in the table, "yEx" means "y×10x"; "CP" means "H6(CN)2 alone"; "TADF" means "dt-BuCbzSulfone alone"; and "x%" means "dt-BuCbzSulfone doped with x mol.% of H6(CN)2").

[0137] 〔Table 5〕 λ(nm) CP TADF 1% 5% 10% 20% 370 2.07E+05 7.44E+05 4.98E+05 5.41E+05 3.55E+05 6.20E+05 375 1.02E+05 1.13E+06 3.26E+05 3.01E+05 2.27E+05 2.97E+05 380 7.21E+04 2.43E+06 3.77E+05 2.97E+05 2.00E+05 1.73E+05 385 5.11E+04 4.92E+06 5.14E+05 3.84E+05 1.97E+05 1.33E+05 390 4.45E+04 8.99E+06 7.63E+05 5.36E+05 2.33E+05 1.15E+05 395 3.83E+04 1.47E+07 1.07E+06 6.65E+05 2.51E+05 1.21E+05 400 3.88E+04 2.09E+07 1.36E+06 8.70E+05 2.72E+05 1.43E+05 405 3.70E+04 2.66E+07 1.70E+06 1.10E+06 2.88E+05 2.02E+05 410 3.71E+04 2.99E+07 2.04E+06 1.36E+06 2.98E+05 2.81E+05 415 5.50E+04 3.12E+07 2.75E+06 1.97E+06 4.08E+05 5.82E+05 420 1.15E+05 3.12E+07 5.73E+06 4.80E+06 8.06E+05 1.96E+06 425 2.34E+05 3.00E+07 1.27E+07 1.18E+07 1.98E+06 6.06E+06 430 3.59E+05 2.84E+07 1.51E+07 1.46E+07 2.73E+06 9.18E+06 435 4.33E+05 2.63E+07 1.25E+07 1.23E+07 2.36E+06 8.70E+06 440 3.84E+05 2.39E+07 9.25E+06 9.10E+06 1.72E+06 6.97E+06 445 3.13E+05 2.13E+07 7.82E+06 7.64E+06 1.35E+06 5.60E+06 450 2.91E+05 1.88E+07 8.89E+06 8.75E+06 1.50E+06 5.97E+06 455 3.10E+05 1.65E+07 1.01E+07 1.01E+07 1.74E+06 7.14E+06 460 3.42E+05 1.41E+07 9.11E+06 9.24E+06 1.63E+06 7.18E+06 465 3.31E+05 1.21E+07 6.97E+06 7.18E+06 1.25E+06 5.89E+06 470 3.07E+05 1.04E+07 5.41E+06 5.51E+06 9.81E+05 4.61E+06 475 2.80E+05 8.93E+06 4.49E+06 4.56E+06 7.81E+05 3.76E+06 480 2.39E+05 7.64E+06 4.07E+06 4.00E+06 6.89E+05 3.31E+06 485 2.30E+05 6.46E+06 3.77E+06 3.74E+06 6.54E+05 3.03E+06 490 2.14E+05 5.61E+06 3.24E+06 3.31E+06 5.86E+05 2.72E+06 495 1.92E+05 4.66E+06 2.68E+06 2.70E+06 4.85E+05 2.30E+06 500 1.77E+05 3.99E+06 2.11E+06 2.16E+06 4.16E+05 1.88E+06 505 1.75E+05 3.38E+06 1.70E+06 1.74E+06 3.23E+05 1.53E+06 510 1.58E+05 2.92E+06 1.40E+06 1.42E+06 2.81E+05 1.25E+06 515 1.47E+05 2.44E+06 1.19E+06 1.19E+06 2.38E+05 1.04E+06 520 1.36E+05 2.11E+06 9.93E+05 9.87E+05 2.10E+05 8.98E+05 525 1.22E+05 1.76E+06 8.67E+05 8.71E+05 1.82E+05 7.53E+05 530 1.08E+05 1.54E+06 7.17E+05 7.17E+05 1.48E+05 6.53E+05 535 9.97E+04 1.36E+06 6.40E+05 6.29E+05 1.41E+05 5.54E+05 540 9.67E+04 1.19E+06 5.06E+05 5.07E+05 1.19E+05 4.57E+05 545 9.13E+04 1.00E+06 4.48E+05 4.22E+05 1.03E+05 3.99E+05 550 8.34E+04 9.05E+05 3.71E+05 3.76E+05 7.38E+04 3.58E+05 555 7.60E+04 7.68E+05 3.33E+05 3.14E+05 7.96E+04 3.02E+05 560 7.38E+04 6.80E+05 2.61E+05 2.87E+05 8.17E+04 2.59E+05 565 6.10E+04 6.00E+05 2.56E+05 2.46E+05 6.65E+04 2.27E+05 570 6.02E+04 5.28E+05 2.01E+05 1.99E+05 5.40E+04 1.93E+05 575 6.05E+04 4.57E+05 1.84E+05 1.76E+05 6.63E+04 1.75E+05 580 5.53E+04 4.03E+05 1.77E+05 1.69E+05 5.30E+04 1.69E+05 585 5.16E+04 3.47E+05 1.47E+05 1.27E+05 4.78E+04 1.46E+05 590 5.15E+04 3.03E+05 1.29E+05 1.23E+05 5.30E+04 1.30E+05 595 4.80E+04 3.01E+05 1.01E+05 1.10E+05 4.26E+04 1.19E+05 600 5.19E+04 2.50E+05 1.06E+05 9.26E+04 4.93E+04 1.13E+05 605 4.56E+04 2.30E+05 9.89E+04 9.77E+04 3.83E+04 1.04E+05 610 4.92E+04 2.12E+05 1.07E+05 9.95E+04 4.38E+04 1.01E+05 615 4.30E+04 2.19E+05 9.00E+04 8.39E+04 4.17E+04 9.02E+04 620 4.60E+04 1.77E+05 9.22E+04 9.38E+04 4.35E+04 8.87E+04 625 4.96E+04 1.57E+05 8.06E+04 7.88E+04 4.10E+04 8.53E+04 630 4.40E+04 1.56E+05 7.82E+04 9.24E+04 6.06E+04 8.60E+04 635 5.96E+04 1.42E+05 7.17E+04 7.53E+04 4.18E+04 8.82E+04 640 7.43E+04 1.68E+05 7.53E+04 8.48E+04 6.31E+04 1.07E+05 645 5.70E+04 1.68E+05 8.56E+04 8.31E+04 4.79E+04 1.07E+05 650 7.65E+04 1.39E+05 9.07E+04 9.07E+04 5.42E+04 1.11E+05

[0138] Table 6 below shows the intensity difference ΔI between the normalized left-handed and right-handed luminescence values ​​of individual dt-BuCbzSulfone (TADF) and compositions composed of dt-BuCbzSulfone with P-H6(CN)2 (P-CP; dashed line) and M-H6(CN)2 (M-CP; solid line) (in an amount of 10 mol.% of the total amount of dt-BuCbzSulfone). Table 6 corresponds to Figure 5. It can be seen that the difference between the normalized left-handed and right-handed luminescence values ​​of H6(CN)2 in the P and M configurations is almost symmetrical through the line segment at coordinate 0. Furthermore, since the normalization is based on the highest peak of the total emission spectrum being normalized to a value of 2, the value of ΔI at the wavelength of the highest total emission peak is defined as glum. Table 5 shows that the maximum intensity of dt-BuCbzSulfone with 10 mol.% H6(CN)2 corresponds to a wavelength of 430 nm. Table 6 shows that at 430 nm, the ΔI values ​​(i.e., glum values) of the compositions with M-H6(CN)2 and P-H6(CN)2 are 1.59 × 10⁻² and 1.44 × 10⁻², respectively.

[0139] 〔Table 6〕 λ(nm) TADF M-CP P-CP λ(nm) TADF M-CP P-CP 380 7.19E-03 1.70E-03 2.77E-03 520 4.40E-04 -1.21E-03 1.11E-03 385 4.83E-03 8.68E-04 2.00E-03 525 4.90E-04 -9.76E-04 7.24E-04 390 3.96E-03 -6.87E-05 1.42E-03 530 3.94E-04 -7.41E-04 8.32E-04 395 3.10E-03 -9.80E-04 8.39E-04 535 4.83E-04 -6.93E-04 6.93E-04 400 2.33E-03 -7.21E-04 8.30E-04 540 4.65E-04 -5.88E-04 5.58E-04 405 1.55E-03 2.29E-05 1.21E-03 545 4.25E-04 -4.67E-04 5.51E-04 410 1.07E-03 1.93E-05 1.55E-03 550 4.93E-04 -4.37E-04 4.12E-04 415 6.44E-04 -1.47E-03 2.64E-03 555 4.70E-04 -3.45E-04 4.36E-04 420 1.21E-04 -6.03E-03 5.97E-03 560 4.60E-04 -9.08E-05 3.19E-04 425 3.16E-04 -1.14E-02 1.07E-02 565 4.42E-04 -1.89E-04 3.48E-04 430 4.81E-04 -1.59E-02 1.44E-02 570 4.30E-04 -7.53E-05 3.59E-04 435 2.83E-04 -1.61E-02 1.56E-02 575 3.92E-04 -1.39E-04 2.12E-04 440 5.28E-04 -1.37E-02 1.33E-02 580 3.50E-04 -7.02E-05 2.94E-04 445 3.48E-04 -1.14E-02 1.13E-02 585 4.05E-04 -2.22E-05 2.43E-04 450 -2.57E-05 -1.09E-02 1.03E-02 590 3.75E-04 -2.97E-05 2.99E-04 455 -3.14E-04 -1.13E-02 1.07E-02 595 4.16E-04 -5.76E-05 2.20E-04 460 -2.30E-04 -1.14E-02 1.06E-02 600 3.36E-04 3.00E-05 1.59E-04 465 -1.32E-04 -1.01E-02 9.55E-03 605 3.44E-04 -1.60E-06 1.35E-04 470 -8.78E-05 -8.29E-03 7.54E-03 610 3.20E-04 -7.47E-05 9.78E-05 475 3.71E-04 -6.53E-03 6.01E-03 615 3.84E-04 -6.42E-06 1.81E-04 480 1.81E-04 -5.13E-03 5.03E-03 620 3.72E-04 6.25E-05 2.25E-04 485 2.74E-05 -4.63E-03 4.01E-03 625 3.69E-04 1.02E-04 1.90E-04 490 2.70E-04 -3.92E-03 3.71E-03 630 3.18E-04 2.50E-04 2.96E-04 495 2.55E-04 -3.39E-03 2.92E-03 635 3.53E-04 9.92E-05 2.75E-04 500 2.94E-04 -2.81E-03 2.45E-03 640 3.02E-04 1.02E-04 2.03E-04 505 5.47E-04 -2.26E-03 1.85E-03 645 2.67E-04 1.29E-04 1.87E-04 510 4.70E-04 -1.62E-03 1.33E-03 650 2.60E-04 1.50E-04 1.96E-04 515 3.59E-04 -1.48E-03 1.25E-03

[0140] Compared to the singlet state of H6(CN)2, which has an energy level of 2.99 eV at 415 nm and 2.92 eV at 425 nm, dt-BuCbzSulfone has higher energy levels in both singlet and triplet states. Furthermore, the emission spectrum of dt-BuCbzSulfone overlaps with the absorption spectrum of H6(CN)2.

[0141] These results indicate that even with only 1% dopant, the luminescence transfer from thermally activated delayed fluorescent molecules to circularly polarized molecules is quantitative, confirming the transfer of non-polarized luminescence from thermally activated delayed fluorescent molecules to circularly polarized molecules that provide circularly polarized luminescence. The total luminescence intensity decreases as the proportion of H6(CN)2 in dt-BuCbzSulfone decreases from 1 mol.% to 10 mol.%. However, it increases from 10 mol.% to 20 mol.%. The composition of Example 1 provides a cyan-blue color.

[0142] Example 8

[0143] The circularly polarized molecule in Example 7 can be replaced by H6(NPh)2 or H6(DPP)2.

[0144] Figure 6 reveals the intensity difference ΔI between left-handed and right-handed luminescence of P-H6(NPh)2 (solid line) and M-H6(NPh)2 (dashed line). It can be observed that P-H6(NPh)2 emits more left-handed polarized light than right-handed polarized light, thus it can be said that P-H6-(NPh)2 emits some degree of left-handed circularly polarized light. Similarly, M-H6(NPh)2 emits more right-handed polarized light than left-handed polarized light, thus it can be said that M-H6-(NPh)2 emits some degree of right-handed circularly polarized light. The maximum value of ΔI between the two molecules is observed to be close to 495 nm. The luminescence quantum yield of H6(NPh)2 is 70%, and the luminescence asymmetry factor is 3 × 10⁻³. H6(NPh)2 provides a green color.

[0145] Figure 7 shows the intensity difference ΔI between left-handed and right-handed luminescence of P-H6(DPP)2 (solid line) and M-H6(DPP)2 (dashed line). It can be observed that P-H6(DPP)2 emits more left-handed polarized light than right-handed polarized light, thus it can be said that P-H6-(DPP)2 emits left-handed circularly polarized light to some extent. Similarly, M-H6(DPP)2 emits more right-handed polarized light than left-handed polarized light, thus it can be said that M-H6-(DPP)2 emits right-handed circularly polarized light to some extent. The maximum value of ΔI between the two molecules is observed to be close to 605 nm. The luminescence quantum yield of H6(DPP)2 is 40%, and the luminescence asymmetry factor is 7 × 10⁻⁴. H6(DPP)2 provides a red color.

[0146] The thermally activated delayed fluorescence molecule of Example 7 can be substituted with Cbz-TRZ2 or 4-CbzIPN, which are described in Adachi et al., 2017 [4] and Adachi et al., 2012 [5], respectively. The thermally activated delayed fluorescence quantum yield of Cbz-TRZ2 is 86%, and that of 4-CbzIPN is 94%.

[0147] The following combinations provide particularly good results: Cbz-TRZ2 with H6(NPh)2, and 4-CbzIPN with H6(DPP)2.

[0148] In addition to the thermally activated delayed fluorescence (TRF) molecules and circularly polarized molecules described herein, many possible combinations of TRF molecules and circularly polarized molecules can be considered to obtain the desired synergistic circularly polarized-thermally activated delayed fluorescence properties. For example, for circularly polarized molecules, other helical hydrocarbon derivatives, helical-like hydrocarbon compounds (where the helical polycyclic compounds are not fully conjugated), biaromatic systems, and palmar molecules with planar palmarity, such as paracyclic aromatic hydrocarbon derivatives, can be considered.

[0149] References

[0150] [1] Longhi, G.; Castiglioni, E.; Koshoubu, J.; Mazzeo, G.; Abbate, S., "circularly polarized Luminescence: A Review of Experimental and Theoretical Aspects", Chirality2016, 28 (10), 696-707

[0151] [2] Dhbaibi, K.; Favereau, L.; Srebro-Hooper, M.; Jean, M.; Vanthuyne, N. ; Zinna, F.; Jamoussi, B.; Di Bari, L.; Autschbach, J.; Crassous, J., “Exciton coupling in diketopyrrolopyrrole–helicene derivatives leads to red and near-infrared circularly polarized luminescence”,Chem. Sci.2018, 9, 735–742

[0152] [3] Zhang, Q.; Li, J.; Shizu, K.; Huang, S.; Hirata, S.; Miyazaki, H.; Adachi, C., “Design of Efficient Thermally Activated Delayed Fluorescence Materials for Pure Blue Organic Light Emitting Diodes”,J. Am. Chem. Soc., 134, 36, 14706–14709 (2012)

[0153] [4] Cui, L.-S.; Nomura, H.; Geng, Y.; Kim, J. U.; Nakanotani, H.; Adachi, C., “Controlling Singlet-Triplet Energy Splitting for Deep-Blue Thermally Activated Delayed Fluorescence Emitters”,Angew. Chem. Int. Ed., 56, 1571 (2017)

[0154] [5] Uoyama, H.; Goushi, K.; Shizu, K.; Nomura, H.; Adachi, C., "Highly efficient organic light-emitting diodes from delayed fluorescence", Nature, 492, 234–238 (2012). [Simplified Explanation of the Diagram]

[0062] Other features, details, and advantages will be disclosed in the following embodiments and accompanying drawings, wherein:

[0063] Figure 1 is a diagram illustrating the underlying principle of the present invention, particularly the energy transfer from the singlet state energy level of thermally activated delayed fluorescent molecules to the singlet state energy level of circularly polarized molecules.

[0064] Figure 2 is a graph showing the absorption spectrum (dashed line) and emission spectrum (solid line) of H6(CN)2 recorded in dichloromethane solvent at room temperature between 250 nm and 600 nm. The values ​​are normalized so that the highest peak value is 1.

[0065] Figure 3 is a graph illustrating the intensity difference ΔI between left-handed and right-handed luminescence of M-H6(CN)2 (dashed line) and P-H6(CN)2 (solid line) recorded at approximately 400 nm and 600 nm in dichloromethane solvent at room temperature. The values ​​are normalized so that the maximum peak Imax in the total emission spectrum is 2. In this case, the value of ΔI at the wavelength of Imax is the glum value at that wavelength.

[0066] Figure 4 is a plot of the emission spectra of H6(CN)2 alone, dt-BuCbzSulfone alone, and compositions of dt-BuCbzSulfone and H6(CN)2 (in amounts of 1, 5, 10 and 20 mol.%) of dt-BuCbzSulfone recorded in thin films at room temperature, between 370 nm and 650 nm.

[0067] Figure 5 is a graph illustrating the intensity difference ΔI between left-handed and right-handed luminescence of BuCbzSulfone alone, and a composition consisting of dt-BuCbzSulfone and M-H6(CN)2 or P-H6(CN)2 (in an amount of 10 mol.%) of dt-BuCbzSulfone, recorded in a thin film at room temperature, between approximately 400 nm and 650 nm. The values ​​correspond to the normalized values ​​of the luminescence intensity in Figure 5. In this case, the value of ΔI at the wavelength of the highest peak in the luminescence spectrum is the glum value at that wavelength.

[0068] Figure 6 is a graph illustrating the intensity difference ΔI between left-handed and right-handed luminescence of M-H6(NPh)2 (dashed line) and P-H6(NPh)2 (solid line) recorded at approximately 400 nm and 650 nm in dichloromethane solvent at room temperature. The values ​​are normalized so that the highest peak value Imax in the total emission (IR + IL) is 2. In this case, the value of ΔI at the wavelength of Imax is the glum value at that wavelength.

[0069] Figure 7 is a graph illustrating the intensity difference ΔI between left-handed and right-handed luminescence of M-H6(DPP)2 (dashed line) and P-H6(DPP)2 (solid line) at approximately 550 nm and 725 nm, recorded in dichloromethane solvent at room temperature. The values ​​are normalized so that the highest peak value Imax in the total emission (IR + IL) is normalized to 2. In this case, the value of ΔI at the wavelength of Imax is the glum value at that wavelength.

Claims

1. An active light-emitting layer composition comprising a thermally activated delayed fluorescence molecule as a host material and a light-emitting molecule with circular polarization characteristics as a dopant.

2. The active light-emitting layer composition as claimed in claim 1, wherein the thermally activated delayed fluorescent molecule exhibits a singlet state energy level and a triplet state energy level, and the singlet state energy level exhibited by the light-emitting molecule is lower than the singlet state energy level and triplet state energy level of the thermally activated delayed fluorescent molecule.

3. The active light-emitting layer composition as claimed in claim 1 or 2, wherein the light-emitting molecule has an absorption spectrum and the thermally activated delayed fluorescent molecule has a light emission spectrum superimposed on the absorption spectrum of the light-emitting molecule.

4. The active light-emitting layer composition as claimed in claim 1 or 2, wherein the active light-emitting layer composition exhibits at least one of the following characteristics: a thermally activated delayed fluorescence quantum yield of 0.01 or more; a light emission quantum yield of 0.10 or more; and a light emission polarization measured by glum value that is not 0.

5. The active light-emitting layer composition as described in claim 1 or 2, wherein the light-emitting molecule is a planar molecule, such as a helical hydrocarbon derivative, a helical hydrocarbon-like compound, a biaromatic system, or a molecule having planar planar planarity (e.g., a paracyclic aromatic hydrocarbon derivative).

6. The active light-emitting layer composition as described in claim 5, wherein the light-emitting molecule is a carbon[6]spiral hydrocarbon derivative having the following general formula in an M or P configuration (hereinafter referred to as H6):

7. The active light-emitting layer composition as claimed in claim 6, wherein B is a connecting chain having one of the following formulas: or a combination thereof.

8. The active light-emitting layer composition as described in claim 6, wherein R is one of the following formulas:

9. The active light-emitting layer composition as claimed in claim 6, wherein the light-emitting molecule is one of the following in a P-configuration or M-configuration: hereinafter referred to as H6(CN)2; hereinafter referred to as H6(Py)2; hereinafter referred to as H6(NH2)2; hereinafter referred to as H6(NMe2)2; hereinafter referred to as H6(TMS)2; hereinafter referred to as H6(NPh)2; and hereinafter referred to as H6(DPP)2.

10. The active light-emitting layer composition as claimed in either claim 1 or 2, wherein the thermally activated delayed fluorescent molecule is a non-peristaltic molecule, such as one of the following: hereinafter referred to as dt-BuCbzSulfone; hereinafter referred to as Cbz-TRZ2; and hereinafter referred to as 4-CbzIPN.

11. The active light-emitting layer composition as claimed in claim 1 or 2, wherein the thermally activated delayed fluorescent molecule and the light-emitting molecule are one of the following combinations: dt-BuCbzSulfone and H6(CN)2; Cbz-TRZ2 and H6(NPh)2; and 4-CbzIPN and H6(DPP)2.

12. A light-emitting device having an active light-emitting layer composition as described in any one of claims 1 to 11.

13. The light-emitting device as claimed in claim 12, wherein the light-emitting device is an organic light-emitting diode.

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