Preparation method and application of a spirofluorene-based h-cae blue light material

Abstract

The application discloses a preparation method and application of a spirofluorene-based grarophane blue light material, and synthesizes a spirofluorene-based grarophane fluorescent material molecule G[2]SBF-TFBZ by adopting a C-H bond activation grating method, wherein the optimal reaction condition is that a catalyst is palladium acetate Pd(OAc), a ligand is tri-tert-butyl phosphonium tetrafluoroborate PtBu2Me-HBF4, a base is potassium carbonate, an organic solvent is N,N-dimethylacetamide DMAc, and the reaction is carried out at 120 DEG C for 48 h, and the reaction concentration is 10 mmol / L. ‑1 The OLED is prepared by adopting a vacuum evaporation technology. The specific device structure is that ITO is used as an anode, HAT-CN is used as a hole transport layer, TAPC / TcTa / mCP is used as an injection layer, G[2]SBF-TFBZ and [3]TFBZ-[2]SBF are used as light emitting layers, and the test results are as follows: the maximum emission wavelengths of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF are 417 nm and 444 nm respectively, the maximum external quantum efficiencies EQEmax are 1.85% and 0.41% respectively, the turn-on voltage of G[2]SBF-TFBZ is 3.9 V, the maximum luminance is 380.7 cd / m ‑2 , and the corresponding current density is 197.1 mA / cm ‑2 . The turn-on voltage of [3]TFBZ-[2]SBF is 4.3 V, the corresponding current density is 187.3 mA / cm ‑2 . Compared with [3]TFBZ-[2]SBF, G[2]SBF-TFBZ has stronger luminance, more excellent efficiency and performance.

Description

Technical Field

[0001] The present invention belongs to the field of organic electroluminescent devices, and in particular relates to a preparation method and application of a spirofluorene-based aromatic hydrocarbon blue light material. Background Art

[0002] Spirobifluorene, a twisted spiro ring structure formed by two fluorene molecules sharing a single carbon atom, exhibits unique non-planar spiro conjugation, a cross-shaped conformation, and steric hindrance. These properties hold great potential for application in organic optoelectronic devices. For example, in OLEDs, electrons must be injected from the cathode into the light-emitting layer. Spirobifluorene's strong electron affinity makes it a highly efficient electron transport material. Furthermore, its spiro ring structure improves charge injection efficiency and reduces charge loss during transport, making it an excellent hole transport material. Most importantly, its conjugated structure imparts excellent fluorescence properties. By manipulating the structure of spirobifluorene-based materials, emission of varying wavelengths and colors can be achieved, making it an ideal luminescent material for the fabrication of efficient and colorful OLEDs. In 2018, we successfully synthesized a spirobifluorenyl "well" lattice using Yamamoto coupling. This is distinct from pure spirobifluorenyl lattice aromatics. In this paper, we synthesized a series of [spirobifluorene-fluorophenyl]-based lattice arenes using a CH activation strategy, characterized their optoelectronic properties, and explored their applications in OLEDs. Summary of the Invention

[0003] The present invention is achieved through the following technical means, and its reaction process is as follows:

[0004]

[0005] The present invention first discloses a spirofluorene-based aromatic fluorescent material. The specific molecular formula of the fluorescent material is shown in formula (I), and the general molecular formula is shown in formula (II):

[0006] in:

[0007] It is a type of spirofluorene compound;

[0008] Select any one of the following structures:

[0009]

[0010] Select any one of the following structures:

[0011]

[0012] Wherein X is selected from any one of F, Cl, Br, I, CH3, NO2, and CH3O.

[0013] Furthermore, the spirofluorene compound The specific structure is as follows:

[0014]

[0015] The present invention also discloses a method for preparing a spirofluorene-based aromatic fluorescent material, comprising:

[0016] Under nitrogen protection, at a reaction temperature of 80-150°C, add a base, a ligand, an organic solvent and a palladium catalyst and react for 36-72 hours.

[0017] The reaction concentration of the reaction system is 10-30mmol·L -1 The molar ratio of type I synthon [2]TFBZ-SBF and dibromospirobifluorene DBrDSBF is 1:1, and the spirofluorene-based aromatic fluorescent material is finally obtained.

[0018] Furthermore, the base is selected from: potassium hydroxide, sodium carbonate, sodium bicarbonate, or a combination of two thereof;

[0019] The ligand is selected from the group consisting of: PtBu2Me-HBF4, phosphoramidite ligands, 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (BINAP), and JosiPhos, or a combination of two thereof;

[0020] The organic solvent is selected from: N,N-dimethylacetamide, dimethyl sulfoxide, toluene, acetonitrile, or a combination of two thereof;

[0021] The palladium catalyst is selected from the group consisting of: tetrakis(triphenylphosphine)palladium, palladium acetate, palladium pivalate, palladium trifluoroacetate, diphenylphosphinodichloropalladium, dichlorobistriphenylphosphine palladium, or one or more combinations of palladium on carbon.

[0022] Furthermore, the base is potassium carbonate; the ligand is PtBu2Me-HBF4; the organic solvent is N,N-dimethylacetamide; and the palladium catalyst is palladium acetate.

[0023] Furthermore, the amount of the palladium catalyst substance is 0.025 to 0.05 times that of the synthon.

[0024] Furthermore, the reaction temperature is 120°C, the reaction time is 48h, and the reaction concentration is 10mmol·L -1 .

[0025] The present invention also discloses a spirofluorene-based aromatic fluorescent material prepared according to any of the above preparation methods.

[0026] The present invention also discloses a use of any of the above-mentioned spirofluorene-based aromatic hydrocarbon blue light materials in the preparation of an electroluminescent device.

[0027] Furthermore, the electroluminescent device is an organic light emitting diode.

[0028] The beneficial effects of the present invention are:

[0029] 1. This invention mainly studies the synthesis, properties and applications of [spirobifluorene-fluorophenyl]-based lattice arenes. First, retrosynthetic analysis confirmed that the step-by-step method was a feasible route. At the same time, the optimal reaction conditions were screened out, using Pd(OAc)2 as a catalyst, PtBu2Me-HBF4 as a ligand, K2CO3 as a base, and DMAc as a solvent. When the concentration was 10mmol·L -1 When the concentration is 20mmol·L -1 When the yield of a spirofluorene-based aromatic fluorescent material G[3]SBF-TFBZ is as high as about 5%.

[0030] 2. To explore the influence of lattice size and lattice hole effect on material performance, detailed characterization of their optoelectronic properties (such as Figure 2 As shown). Spectral measurements show that in solution, as the lattice size increases, the maximum absorption wavelength of G[3]SBF-TFBZ red-shifts by 7nm compared to G[2]SBF-TFBZ; while in thin film, the maximum emission wavelength of G[3]SBF-TFBZ blue-shifts by 13nm compared to G[2]SBF-TFBZ. It should be noted that in both thin film and solution states, the maximum emission wavelengths of G[2]SBF-TFBZ and G[3]SBF-TFBZ are blue-shifted compared to linear molecules. In addition, as the lattice size increases, the PLQY of G[3]SBF-TFBZ is lower than that of G[2]SBF-TFBZ. Compared to linear molecules, the fluorescence lifetime of the lattice is shorter, and their PLQYs are close. The electrochemical results show that the band gaps of G[2]SBF-TFBZ, [3]TFBZ-[2]SBF, G[3]SBF-TFBZ and [4]TFBZ-[3]SBF are 3.49 eV, 4.62 eV, 4.07 eV and 3.50 eV, respectively. It can be seen that the band gap of G[2]SBF-TFBZ becomes slightly narrower after lattice formation, but the band gap of G[3]SBF-TFBZ becomes significantly wider.

[0031] 3. They were used as OLED light-emitting layers for application research. The results showed that the turn-on voltage of G[2]SBF-TFBZ was 4V and the maximum brightness reached 380.7cd·m -2, maximum external quantum efficiency EQEmax 1.85%. It can be seen that, compared with linear molecules, [spirobifluorene-fluorobenzene] based garene G[2]SBF-TFBZ has stronger brightness, more excellent efficiency and performance. Surprisingly, the device EL spectrum shows that G[2]SBF-TFBZ effectively suppresses the appearance of the "green band phenomenon". These findings reveal the relationship between molecular structure and luminescent properties, providing an important clue for the directional design of materials with specific luminescent properties. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 For structural characterization of the present application, (a) is the mass spectrum of [3]TFBZ-[2]SBF, (b) is the mass spectrum of [4]TFBZ-[3]SBF, (c) is the mass spectrum of G[2]SBF-TFBZ, (d) is the mass spectrum of G[3]SBF-TFBZ, (e) is the nuclear magnetic superimposed spectrum of [3]TFBZ-[2]SBF and G[2]SBF-TFBZ, (f) is the nuclear magnetic superimposed spectrum of [4]TFBZ-[3]SBF and G[3]SBF-TFBZ.

[0033] Figure 2 For photophysical characterization of the present application, (a) is the spectrum of [3]TFBZ-[2]SBF, [4]TFBZ-[3]SBF, G[2]SBF-TFBZ and G[3]SBF-TFBZ in solution; (b) is the spectrum of [3]TFBZ-[2]SBF, [4]TFBZ-[3]SBF, G[2]SBF-TFBZ and G[3]SBF-TFBZ in thin film; (c) is the photoluminescence quantum efficiency (PLQY) of [3]TFBZ-[2]SBF, [4]TFBZ-[3]SBF, G[2]SBF-TFBZ and G[3]SBF-TFBZ in thin film; (d) is the fluorescence lifetime of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF in different states; (e) is the fluorescence lifetime of G[3]SBF-TFBZ and [4]TFBZ-[3]SBF in different states.

[0034] Figure 3 For CV electrochemical test of the present application, (a) is the electrochemical oxidation and reduction performance diagram of [3]TFBZ-[2]SBF, [4]TFBZ-[3]SBF, G[2]SBF-TFBZ and G[3]SBF-TFBZ; (b) is the energy level diagram of [3]TFBZ-[2]SBF, [4]TFBZ-[3]SBF, G[2]SBF-TFBZ and G[3]SBF-TFBZ.

[0035] Figure 4The test results of the corresponding evaporated OLED devices of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF are shown in the figures, (a) is the EL spectrum of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF; (b) is the external quantum efficiency EQE of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF; (c) is the J-V-L curve of G[2]SBF-TFBZ; (d) is the CE and PE of G[2]SBF-TFBZ as a function of current density; (e) is the J-V-L curve of [3]TFBZ-[2]SBF; (f) is the CE and PE of [3]TFBZ-[2]SBF as a function of current density. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and effects of the present application clearer and more explicit, the present application and the drawings are further described in detail below. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0037] If the specific experimental steps or conditions are not specified in the examples, the conventional experimental steps or conditions described in the literature in the art can be used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0038] All raw materials and reagents used in the present application, including 2,2'-dibromo-9,9'-spirobifluorene (DBrSBF), 1,2,4,5-tetrafluorobenzene, boron tetrafluoride ditertiary butyl methyl phosphide (PtBu2Me-HBF4), palladium acetate (Pd(OAc)2), potassium carbonate (K2CO3), N,N'-dimethylacetamide (DMF), PEDOT:PSS, and other drugs or solvents were purchased from Anjie, Leyen, Makclin, Aradin, or the National Pharmaceutical Group. All drugs and solvents were used directly without further treatment after purchase. All experiments performed in Schlenk reaction tubes were completed in a glove box, and all reactions were ensured to be performed under a nitrogen atmosphere.

[0039] Example 1

[0040] [n+1]TFBZ-[n]SBF

[0041] The reaction equation of the product ([n+1]TFBZ-[n]SBF) is shown as follows:

[0042]

[0043] All the instruments required during the reaction, including: Schlenk reaction flask, magnetic stirrer, were cleaned in advance and dried in the oven, ready for use. First, the reaction flask was fixed on the iron stand, and the device was wrapped with tin foil to ensure light-proof conditions. Then, accurately weighed solid chemicals DBrSBF (0.170 g, 1 equiv), K2CO3 (0.276 g, 2 equiv), Pd(OAc)2 (0.008 g, 0.1 equiv), Pd(PPh3)4 (0.018 g, 0.2 equiv) and Pd2(dba)3 (0.018 g, 0.2 equiv) were added to the reaction tube with a needle tube. After all the reactants and solvents were added, the reaction device was vacuumed, filled with nitrogen, and repeated three times. The plug was tightened under nitrogen to prevent gas leakage. Finally, the device was transferred to the oil bath, and the temperature was set to 120°C. The reaction was completed after 48 h of condensation reflux. After the reaction cooled to room temperature, the high-boiling solvent DMAc was removed by multiple extractions with ethyl acetate / water. The sample was mixed using a rotary evaporator, and 100-200 mesh silica gel powder was used to separate and purify the sample on a 30 cm high chromatography column. Elution was performed using an eluent with a polarity of [petroleum ether: dichloromethane = 8:1], and solid products [2]TFBZ-SBF, [3]TFBZ-[2]SBF and [4]TFBZ-[3]SBF were obtained with yields of 40%, 26% and 23%, respectively. t Bu2Me-HBF4 (0.018 g, 0.2 equiv) and Pd(OAc)2 (0.008 g, 0.1 equiv), 1,2,4,5-tetrafluorobenzene (0.16 ml, 4 equiv) and solvent DMAc (20 ml) were added to the reaction tube with a needle tube. After all the reactants and solvents were added, the reaction device was vacuumed, filled with nitrogen, and repeated three times. The plug was tightened under nitrogen to prevent gas leakage. Finally, the device was transferred to the oil bath, and the temperature was set to 120°C. The reaction was completed after 48 h of condensation reflux. After the reaction cooled to room temperature, the high-boiling solvent DMAc was removed by multiple extractions with ethyl acetate / water. The sample was mixed using a rotary evaporator, and 100-200 mesh silica gel powder was used to separate and purify the sample on a 30 cm high chromatography column. Elution was performed using an eluent with a polarity of [petroleum ether: dichloromethane = 8:1], and solid products [2]TFBZ-SBF, [3]TFBZ-[2]SBF and [4]TFBZ-[3]SBF were obtained with yields of 40%, 26% and 23%, respectively.

[0044] Example 2

[0045] [2]TFBZ-SBF

[0046]

[0047] 1 H NMR (400 MHz, CDC13): δ 7.95 (d, J = 7.9 Hz, 2H), 7.88 (d, J = 7.6 Hz, 2H), 7.48 (d, J = 8.0 Hz, 2H), 7.40 (t, J = 7.5 Hz, 2H), 7.17 (t, J = 7.5 Hz, 2H), 7.01 - 6.91 (m, 2H), 6.86 (s, 2H), 6.81 (d, J = 7.6 Hz, 2H); 13 C NMR (101 MHz, CDC13) δ 147.6, 147.5, 141.7, 139.8, 128.9, 127.5, 127.0, 125.7, 124.8, 123.1, 123.1, 119.4, 119.1, 103.7, 103.5, 103.3.

[0048] Example 3

[0049] [3] TFBZ - [2] SBF:

[0050]

[0051] 1 H NMR (400 MHz, CDC13): δ 7.92 (dd, J = 8.0, 4.7 Hz, 2H), 7.86 (d, J = 7.7 Hz, 2H), 7.45 (t, J = 7.6 Hz, 2H), 7.39 (d, J = 7.9, 4.1, 1.9 Hz, 2H), 7.20 - 7.11 (m, 2H), 7.01 - 6.86 (m, 2H), 6.85 - 6.75 (m, 4H); 13 C NMR (101 MHz, CDC13) δ 147.5, 147.5, 141.7, 141.6, 139.9, 139.8, 128.9, 127.5, 127.0, 124.9, 124.8, 123.1, 119.4, 119.1, 103.5, 96.2, 85.4.

[0052] Example 4

[0053] [4] TFBZ - [3] SBF:

[0054]

[0055] 1 H NMR (400 MHz, CDC13): δ 7.88 - 7.74 (m, 12H), 7.40 - 7.25 (m, 12H), 7.15 (dt, J = 12.0, 7.3 Hz, 4H), 6.85 (ddt, J = 10.7, 8.6, 4.4 Hz, 2H), 6.97 - 6.89 (m, 2H), 6.77 - 6.67 (m, 10H); 13 C NMR (101 MHz, CDC13) δ 147.6, 147.5, 141.7, 141.6, 139.9, 139.8, 139.8, 128.9, 127.5, 127.5, 127.0, 125.7, 124.8, 123.1, 123.1, 119.4, 119.4, 119.1, 103.5.

[0056] Example 5

[0057] The reaction equation of this product (G[2]SBF-TFBZ) is shown below:

[0058]

[0059] All the instruments required during the reaction, including Schlenk reaction flask, magnetic bar, were washed clean in advance and dried in the oven, ready for use. First, the reaction flask was fixed on the iron stand and wrapped with tin foil to ensure lightproof conditions. The solid drugs [2] TFBZ-SBF (0.123 g, 1 equiv), DBrDSBF (0.095 g, 1 equiv), K2CO3(0.070 g, 2 equiv), P t Bu2Me-HBF4(0.010 g, 0.2 equiv) and Pd(OAc)2(0.004 g, 0.1 equiv) were added to the reaction tube, and then DMAc (20 ml) was added by a needle tube. After all the drugs were added, the device was vacuumed and filled with nitrogen, repeated three times, and the plug was tightened under the nitrogen environment. Finally, the device was transferred to the oil bath, and the temperature was set to 120°C. After 48 h of condensation reflux, the reaction was completed. After the reaction was cooled to room temperature, extraction was performed with ethyl acetate / water. Then the sample was mixed by rotary evaporation, 200-300 mesh silica gel powder was loaded into a 25 cm high chromatography column for separation and purification, and elution was performed with an eluent with polarity [petroleum ether: dichloromethane = 8:1] to obtain solid product G[2]SBF-TFBZ with a yield of 20%. 1 H NMR (400 MHz, CDC13): δ 7.97 (d, J = 8.1 Hz, 1H), 7.95-7.91 (m, 1H), 7.89-7.80 (m, 4H), 7.45 (tt, J = 9.2, 1.3 Hz, 2H), 7.41-7.30 (m, 4H), 7.17-7.07 (m, 6H), 6.83-6.74 (m, 6H); 13 C NMR (101 MHz, CDC13): δ 147.9, 147.3, 147.3, 147.3, 147.2, 146.9, 140.4, 140.4, 139.6, 139.5, 139.5, 128.6, 128.4, 127.3, 127.1, 126.8, 126.6, 126.5, 124.6, 122.8, 119.1, 119.0, 118.8, 118.7.

[0060] Example 6

[0061] G[3]SBF-TFBZ

[0062] The reaction equation of this product (G[3]SBF-TFBZ) is shown below:

[0063]

[0064] All the instruments required in the reaction process, including Schlenk reaction flask, magnetic sub, were washed clean in advance, put into the oven to dry, and used later. First, fix the reaction flask on the iron stand, wrap it with tin foil to ensure light-proof conditions. Then accurately weigh the solid drugs [3] TFBZ-[2] SBF (0.430 g, 1 equiv), DBrSBF (0.188 g, 1 equiv), K2CO3 (0.190 g, 2 equiv), P t Bu2Me-HBF4(0.020g,0.2equiv)and Pd(OAc)2(0.008g,0.1equiv), and then use a needle tube to suck solvent DMAc (20 ml) into the reaction tube. After all the drugs and solvents are added to the reaction tube, the device is vacuumed, and nitrogen is blown, which is repeated three times, and the plug is tightened under nitrogen. Finally, the device is transferred to the oil bath, and the temperature is set to 110°C. After 48 h of condensation reflux, the reaction is completed. After the reaction is cooled to room temperature, extraction is performed with ethyl acetate / water. Then the sample is stirred using a rotary evaporator, 200-300 mesh silica gel powder is packed into a 35 cm high chromatography column for separation and purification, and the eluent is adjusted to [petroleum ether: dichloromethane = 10:1] to elute. After the unreacted substrate is eluted, the eluent polarity is adjusted to [petroleum ether: dichloromethane = 6:1], and multiple elutions are performed to obtain a yellowish solid product G[3]SBF-TFBZ with a yield of 5%. 1 HNMR (400 MHz, CDCl3): 1 HNMR (400 MHz, CDCl3): δ 7.94 (dd, J = 11.9, 8.0 Hz, 3H), 7.89-7.81 (m, 6H), 7.56-7.51 (m, 3H), 7.44 (d, J = 7.9 Hz, 3H), 7.40-7.32 (m, 6H), 7.13 (dd, J = 8.3, 3.0 Hz, 9H), 7.08 (d, J = 7.7 Hz, 3H), 6.88 (d, J = 17.8 Hz, 3H), 6.83-6.77 (m, 3H), 6.69 (d, J = 7.7 Hz, 3H).

[0065] Application Example 1

[0066] The OLED device prepared by the vacuum evaporation method and the characterization process are as follows:

[0067] ITO-glass substrates were also cleaned in an ultrasonic cleaner in advance, and then dried in an oven at 120°C for 2h. The ITO-glass substrates were first treated by ozone UV for 10min, and then HAT-CN layer with thickness of 10nm, TAPC layer with thickness of 50nm, TcTa layer with thickness of 5nm and mCP layer with thickness of 5nm were prepared by vacuum evaporation process under vacuum degree of 1x10-4mbar, respectively. Then, G[2]SBF-TFBZ and [3]TFBZ-[2]SBF layers with thickness of about 20nm were prepared by vacuum evaporation process at temperature of 130°C with evaporation rate of 1A·s -1 -1A·s

[0068] OLEDs were prepared by vacuum evaporation technology.

[0069] The specific device structure was ITO as anode, HAT-CN as hole transport layer, TAPC / TcTa / mCP as injection layer, G[2]SBF-TFBZ and [3]TFBZ-[2]SBF as light-emitting layer, PPF as injection layer, TPBi as electron transport layer, LiF as hole blocking layer, and Al as cathode. The test results were as follows:

[0070] According to the results Figure 4 a, it can be seen that the EL spectra of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF, and the internal insert is the photo of the corresponding device lighting under voltage driving. As can be seen from the figure, the maximum emission wavelength of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF is 417nm and 444nm respectively, and the linear molecule [3]TFBZ-[2]SBF has "green band phenomenon".

[0071] According to the results Figure 4 b, it can be seen that the EQEmax of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF is 1.85% and 0.41% respectively.

[0072] According to the results Figure 4 c and Figure 4 e, it can be seen that the J-V-L curve of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF. The turn-on voltage of G[2]SBF-TFBZ is 3.9V, and the maximum luminance is 380.7cd·m -2 -1A·cm -2The turn-on voltage of [3]TFBZ-[2]SBF is 4.3 V, and the maximum brightness is up to 363.3 cd·m -2 The corresponding current density is 187.3 mA·cm -2 .

[0073] According to Figure 4 d and 4f results: they are the CE and PE of the current density change graph. Among them, the maximum current efficiency of G[2]SBF-TFBZ and [3]TFBZ-[2]SBF is 2.7 cd·A -1 and 0.59 cd·A -1 , the maximum power efficiency is 1.68 lm·W -1 and 0.32 lm·W -1 .

[0074] The above only describes the preferred embodiments of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered within the scope of the present application.

Claims

1. A spirofluorene-based aromatic fluorescent material, the molecular formula of which is shown in formula (II): Formula (II); wherein: Select any one of the following structures: ， ； Select any one of the following structures: ； ， Wherein X is selected from any one of F, Cl, Br, I, CH3, NO2, and CH3O.

2. The spirofluorene-based aromatic fluorescent material according to claim 1, wherein: , the specific structure is as follows: 。 3. A spirofluorene-based aromatic fluorescent material, the specific molecular formula of which is shown in formula (I): Formula (I).

4. Use of the spirofluorene-based aromatic blue light material according to any one of claims 1 to 3 in the preparation of an electroluminescent device.

5. The use according to claim 4, wherein: The electroluminescent device is an organic light emitting diode.

Images