Phosphorescent complex comprising iridium or platinum, production method thereof, its use in the preparation of optoelectronic devices

Abstract

The present invention relates to a phosphorescent metal complex, synthetic intermediates suitable for the preparation thereof, related synthetic methods and OLEDs containing it. The phosphorescent metal complex is characterized by having a structure of formula (I), comprising at least one substituted benzo[1,2-b:4,5- b']dithiophenyl-isoquinolate binder (iqbdt-der): Formula I wherein M is a metal selected from Ir(III) and Pt(II), m is an integer comprised between 1 and 2, L is a bidentate binder and n is an integer comprised between 1 and 2, the sum of n and m is equal to 2 or 3, R1 is a substituent selected from the group consisting of -H; -F; -CF3; -CN; - C6Fs - COOR2 and -CONR3R4, wherein R2, R3 and R4 are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls preferably selected from phenyl, 2- methylbenzene, 2,4-dimethylbenzene, 2,4,6-trimethylbenzene, k is the charge of the complex and is equal to 0 or +1, and X is an anion, preferably selected from Cl-, BF4 -, or PF6 -, wherein j is the coefficient of the anion X and is equal to 0 or 1.

Description

[0001] PHOSPHORESCENT COMPLEX COMPRISING IRIDIUM OR PLATINUM, PRODUCTION METHOD THEREOF, ITS USE IN THE PREPARATION OF OPTOELECTRONIC DEVICES

[0002] DESCRIPTION

[0003] FIELD OF THE INVENTION

[0004] 5 The present invention falls in the field of near-infrared (NIR) phosphorescent organometallic compounds, their synthetic preparation method, and their use in the preparation of optoelectronic devices.

[0005] STATE OF THE ART

[0006] Organic light-emitting diodes (OLEDs) are optoelectronic devices consisting of thin

[0007] 10 organic films located between two electrodes (one of which is transparent, to allow the emission of light). Under applied voltage, these systems are capable of emitting light based on the luminescence properties of the emitting layer.1

[0008] OLEDs emitting in the visible region of the electromagnetic spectrum have been the subject of extensive research in recent decades, with applications in displays and 15 lighting technologies. Screens and TVs based on this technology are available on the market.

[0009] Interest in extending the emission range of OLEDs to deep red and NIR (between 700 nm and 2500 nm) is growing. Their potential applications, dictated by military1, civilian and telecommunications needs, range from night vision displays and sensors, 20 to fibre optic telecommunications2. Currently, particular importance is given to NIR systems useful in the automotive sector as well as those made on curved or flexible supports. Furthermore, the low optical absorption in the 700-1000 nm region of biological tissues allows the use of NIR emitters in biological applications, such as bioimaging and sensors.

[0010] 25 Near infrared (NIR) emitters suitable for application in OLEDs have been developed using pure organic molecules (difficultly polymers) or organometallic compounds.2, 3>4In particular, phosphorescent materials, which allow the collection of both single- and triplet excitons, are preferred over fluorescent ones.

[0011] In this regard, phosphorescent OLEDs (PHOLEDs) have shown good external 30 quantum efficiency (EQE) in the 650-800 nm range, employing platinum-porphyrins or excimers from platinum complexes in a sophisticated high-vacuum or ultra-high- vacuum growth device architecture.5, 6 Recently, Tuong Ly et al. obtained a state-of-the-art NIR-OLED, based on a homoleptic complex of Pt(II) having two substituted 2-pyrazinyl pyrazolate binders, with an electroluminescence peak at 740 nm and an overall EQE of 24%, but employing an emissive layer consisting solely of the platinum complex.7

[0012] However, the main disadvantages of PHOLEDs are attributable to an effect generally referred to as efficiency roll-off, i.e., the decrease of EQE at high brightness levels (above 1000 cd m'2), and at high current densities. To limit this effect, phosphorescent cyclometallated transition metal complexes (e.g., containing Ir (III)8, 9>Os (II)10, Re(I)11) having octahedral geometry have recently been studied.

[0013] Tao et al. obtained a roll-off of negligible efficiency in Ir(III)-based OLEDs, produced by solution or vacuum methods, emitting between 700 and 800 nm, with an EQE of about 2%.12

[0014] Until now, the OLEDs produced with solution methods have shown lower performance (in terms of efficiency and stability) with respect to those produced under vacuum, but the former could represent a more environmentally sustainable solution for the development of future, efficient NIR-OLEDs.

[0015] In general, in fact, with respect to vacuum techniques, OLED manufacturing methods by solution processing have numerous advantages, including lower material consumption, less expensive processing, and larger scale production.21

[0016] In this regard, the results of a series of studies are reported below, in which NIR- OLEDs processed in solution or vacuum were developed, following different approaches.

[0017] Cao et al. report an optimized OLED processed in Ir(III)-based solution with an emission maximum at 690 nm and an EQE value of 5.7%.13

[0018] Ikawa et al. report a homoleptic complex fac-[Ir(i qbt)s], which incorporates electronrich benzothiophene functionalities, capable of emitting at 690 nm with a good efficiency. A solution-processed OLED with an EQE of 1.4% was manufactured with the same complex.14

[0019] You et al. report optimized solution-processed devices with peak emission at 730 nm and EQE of 6.9%, prepared with Ir(III) complexes.15

[0020] Chen et al. obtained the highest EQEs, reaching 10.62% at 690 nm and 9.59% at 706 nm, for NIR emission devices based on iridium (III) complexes, achieved by vacuum- deposited OLEDs, using a phenyl-isoquinoline and a thienyl-isoquinoline substituted with the cyano group, respectively.16

[0021] Recently, the synthesis of heteroleptic derivatives Ir(CAN)2L (where L is a p- diketonate) has been shown to be an effective strategy to precisely regulate the emission energy of a given low-energy emitting binder.

[0022] In this regard, Penconi et al. studied some Ir(CAN)2iqbt heteroleptic complexes, thus having only one emissive binder (iqbt) and two ancillary binders (CAN). These complexes were characterized electrochemically. The energy difference (Eg) between the frontier molecular orbitals (H0M0-LUM0), calculated from the redox potentials obtained by cyclic voltammetry in DMF with 0.1 M TBAP, at a scanning speed of 200 mV s'1were comprised between 2.30 eV and 2.44 eV. Furthermore, all the complexes studied showed an emission in the NIR with a quantum luminescence efficiency comprised between 13% and 14%, quite similar to the corresponding homoleptic complex [Ir(iqbt)s], but with a molecular weight about 25% lower. The complex [Ir(ppz)2(iqbt)] was used as an emissive dopant in vacuum-processed OLEDs, and its properties were compared with those of the corresponding homoleptic complex [Ir(iqbt)3]. An overall EQE of 3% was achieved.17

[0023] Finally, Kesarkar et al. developed and tested a state-of-the-art OLED with an EQE of 3.07% based on the [Ir(iqbt)2(dpm)] complex with peak emission at 714 nm (range 680-820 nm).18

[0024] In addition to OLEDs, a more recent frontier of optoelectronic devices is represented by organic field effect transistors with light emission (OLET), which constitute a bifunctional technology, as they are capable of operating as a field effect transistor and, at the same time, generate light like an OLED, within a semiconductor channel.

[0025] In its simplest structure, a typical OLET consists of: a conductive substrate (also transparent), called a gate electrode or more simply gate, on which an insulating dielectric layer is placed; in turn, an organic layer (or active semiconductor) is deposited on the insulating dielectric layer, containing small amounts of an emissive organic material; finally, electrodes, commonly known as source and drain, are placed on the active semiconductor layer.

[0026] Finally, among optoelectronic devices and, in particular, among solid-state devices for lighting alternatives to OLEDs, light-emitting electrochemical cells (LECs) are included. These are solid-state devices which can be made on large surfaces and with solution processing methods, using low-cost techniques, thanks to their simple architecture and the possibility of using electrodes stable in air.

[0027] Problems of the background art

[0028] There is currently still some difficulty in making NIR-OLEDs with a good EQE, since it decreases at high brightness levels (above 1000 cd m'2), an effect generally referred to as efficiency roll-off, which leads to a significant increase in power consumption and a reduction in the operating life of the device.

[0029] Furthermore, although the manufacture of NIR-OLEDs by solution processing techniques can have the advantages described above, NIR-emitting phosphorescent materials with a good luminescence quantum efficiency, suitable for the preparation of NIR-OLEDs with such solution processing techniques, are still rather rare.

[0030] In fact, the use of such methods still involves numerous critical issues, including the need to have a good resistivity of the solvent and materials which are suitably workable in solution and, at the same time, which allow to obtain OLEDs with performance, in terms of efficiency and stability, at least comparable to the corresponding devices produced with vacuum methodologies.

[0031] SUMMARY OF THE INVENTION

[0032] In this context, the Applicant has developed a phosphorescent metal complex comprising at least one substituted benzo[l,2-b:4,5-b']dithiophene-isoquinoline binder (iqbdt-der), having a structure of formula (I): wherein

[0033] M is a metal selected from Ir(III) and Pt(II), m is an integer comprised between 1 and 2,

[0034] L is a bidentate binder and n is an integer comprised between 1 and 2, the sum of n and m is equal to 2 or 3,

[0035] R1is a substituent selected from the group consisting of -H; -F; -CF3; -CN; - CeFs - COOR2and -CONR3R4,

[0036] R2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls preferably selected from phenyl, 2- methylbenzene, 2,4-dimethylbenzene, 2,4,6-trimethylbenzene, k is the charge of the complex and is equal to 0 or +1, and

[0037] X is an anion, preferably selected from Cl", BFL, or PFe', wherein j is the coefficient of the anion X and is equal to 0 or 1.

[0038] The synthetic intermediates for the preparation of the metal complex object of the present invention are also of interest for protection; such intermediates are characterized by the structure formulas (I5), (L) or (I7).

[0039] A further object of the present invention are the methods for preparing metal complexes of Ir(III) and Pt(II), as defined by the current claims 8 and 9.

[0040] Finally, optoelectronic (organic) light-emitting devices are claimed which include the aforementioned phosphorescent metal complex.

[0041] Advantages of the invention

[0042] The complexes of the invention have the following technical advantages:

[0043] - they are characterized by near-infrared emission with a good quantum luminescence efficiency, thanks to the presence of heavy metals, such as iridium and platinum, which determine a strong spin-orbit coupling, and also thanks to an intrinsic conformational rigidity.

[0044] - they are easy to prepare synthetically, and are obtained by the method of the invention with good reaction yields.

[0045] - they are suitable for the production of NIR-OLEDs, both by vacuum deposition techniques and by solution deposition techniques, depending on the applications of interest.

[0046] - they have a good solubility in polar organic solvents, possibly halogenated, such as chlorobenzene, methylene chloride, toluene xylene, tetrahydrofuran (THF), or acetonitrile (ACN), which makes them particularly suitable for the preparation of OLEDs by solution deposition. In fact, the complexes of the invention are also easily processable by low-cost wet deposition techniques, such as spin-coating, doctor blade, and possibly inkjet and roll-to-roll printing, allowing OLEDs to be produced over a wide surface. It should be noted that, with respect to the compounds described in Kesarkar et al., the complexes of the invention are easily characterized by1H NMR, given the presence of at least one characteristic singlet, which identifies a hydrogen atom of the benzene ring of the substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolate binder.

[0047] Advantageously, the complexes of the invention, although they have an emission at higher wavelength values than those of the complexes described in Kesarkar et al., are characterized by substantially comparable luminescence quantum efficiency values ( L). It should be noted that such a result is quite surprising and unexpected, in light of the theory of the energy gap law, according to which shifts of the emission wavelength towards the NIR (higher wavelengths) are generally associated with reductions in the luminescence quantum efficiency.

[0048] Still advantageously, the OLEDs produced with the complexes of the invention are characterized by a homogeneous emission over a wide surface, have a low energy consumption, an appreciable lightness, a good mechanical flexibility, and an ease of integration into the architecture of the devices.

[0049] DESCRIPTION OF THE FIGURES

[0050] Figure 1 : graph, related to the OLED of the invention, in which a generic photoluminescence emission curve and a generic electroluminescence emission curve are shown. It should be noted that such a graph is reported merely for illustrative purposes, and is therefore to be understood as a summary of the photoluminescent and electroluminescent properties of the complexes of the invention used in the creation of the OLED.

[0051] Figure 2: graph, related to the intermediate of formula (Is), in which the following curves are reported: an absorption curve, obtained at room temperature (RT) in CH2Q2, at neutral / basic pH; an absorption curve, obtained at RT in CH2CI2, at acidic pH; an emission curve, obtained at RT in CH2CI2, at neutral / basic pH; an emission curve, obtained at RT in CH2Q2, at acidic pH; an emission curve, obtained at 77 K in 2-methyltetrahydrofuran (2-MeTHF).

[0052] Figure 3: 'H NMR spectrum, obtained in CD2Q2 at a frequency of 300 MHz, of the complex of Ir(III), [Ir(iqbdt)(ppz)2].

[0053] Figure 4: expansion of the 'H NMR spectrum illustrated in Figure 3.

[0054] Figure 5: ^^H COSY-NMR spectrum, obtained in CD2CI2 at a frequency of 300 MHz, of the complex of Ir(III), [Ir(iqbdt)(ppz)2]. Figure 6: graph, related to the complex of Ir(III), [Ir(iqbdt)(ppz)2], in which the following curves are reported: an absorption curve, obtained at RT in CH2CI2, an excitation curve, obtained at RT in CH2Q2; an excitation curve, obtained at 77 K in 2- MeTHF; an emission curve, obtained at RT in CH2CI2; an emission curve, obtained at 77 K in 2-MeTHF.

[0055] Figure 7: 'H NMR spectrum, obtained in CD2Q2 at a frequency of 300 MHz, of the complex of Ir(III), [Ir(iqbdt)2(dpm)].

[0056] Figure 8: expansion of the 'H NMR spectrum illustrated in Figure 7.

[0057] Figure 9: COSY-NMR spectrum, obtained in CD2CI2 at a frequency of 300

[0058] MHz, of the complex of Ir(III), [Ir(iqbdt)2(dpm)].

[0059] Figure 10: graph, related to the complex of Ir(III), [Ir(iqbdt)2(dpm)], in which the following curves are reported: an absorption curve, obtained at RT in CH2Q2; an excitation curve, obtained at RT in CH2Q2; an excitation curve, obtained at 77 K in 2- MeTHF; an emission curve, obtained at RT in CH2CI2; an emission curve, obtained at 77K in 2-MeTHF; an emission curve, obtained at RT in cyclohexane (1% quantum yield).

[0060] Figure 11 :XH NMR spectrum, obtained in CDCh at a frequency of 300 MHz, of the complex of Ir(III), [Ir(iqbdt)3].

[0061] Figure 12: expansion of the 'H NMR spectrum illustrated in Figure 11.

[0062] Figure 13: ^^H COSY-NMR spectrum, obtained in CDCh at a frequency of 300 MHz, of the complex of Ir(III), [Ir(iqbdt)3].

[0063] Figure 14: graph, related to the complex of Ir(III), [Ir(iqbdt)3], in which the following curves are reported: an absorption curve, obtained at RT in CH2Q2; an excitation curve, obtained at RT in CH2CI2; an excitation curve, obtained at 77 K in 2-MeTHF; an emission curve, obtained at RT in CH2Q2; an emission curve, obtained at 77K in 2-MeTHF; an emission curve, obtained at RT in DMSO.

[0064] Figure 15: aXH NMR spectrum, obtained in CDCh at a frequency of 300 MHz, of the complex of Pt(II), [Pt(iqbdt)(dpm)] is shown.

[0065] Figure 16: expansion of the 'H NMR spectrum illustrated in Figure 15.

[0066] Figure 17: ^^H COSY-NMR spectrum, obtained in CDCh at a frequency of 300 MHz, of the complex of Pt(II), [Pt(iqbdt)(dpm)]. Figure 18: graph, related to the complex of Pt(II), [Pt(iqbdt)(dpm)], in which the following curves are reported: an absorption curve, obtained in CH2CI2; an excitation curve, obtained at RT in CH2CI2; an emission curve, obtained at RT in CH2Q2; an emission curve, obtained at 77 K in 2-MeTHF.

[0067] Figure 19:XH NMR spectrum, obtained in CD2Q2 at a frequency of 300 MHz, of the intermediate of formula (I5) of Example no. 11 or 12.

[0068] Figure 20: expansion of the 'H NMR spectrum illustrated in Figure 19.

[0069] Figure 21 : COSY-NMR spectrum, obtained in CD2CI2 at a frequency of 300

[0070] MHz, of the intermediate of formula (I5) of Example no. 11 or 12.

[0071] Figure 22:13C NMR spectrum, obtained in CD2Q2 at a frequency of 300 MHz, of the intermediate of formula (I5) of Example no. 11 or 12.

[0072] Figure 23: expansion of the13C NMR spectrum illustrated in Figure 22.

[0073] Figure 24: graph, related to the intermediate of formula (I5) of Example no. 11 or 12, in which the following curves are reported: an absorption curve, obtained at RT in CH2Q2, an excitation curve, obtained at RT in CH2CI2; an excitation curve, obtained at 77 K in 2-MeTHF; an emission curve, obtained at RT in CH2Q2; an emission curve, obtained at 77K in 2-MeTHF.

[0074] Figure 25: a) electroluminescence spectrum for an embodiment of the OLED; b) a curve of the EQE (%) as a function of current density (A / cm2) is shown for the OLED of Exampl e no. 13.

[0075] Figure 26: represents a diagram of the structure of a generic OLED device comprising an emitter layer is shown.

[0076] DETAILED DESCRIPTION OF THE INVENTION

[0077] Definitions

[0078] "Complex" or "coordination compound" is intended as a chemical compound containing a coordination entity, i.e., an ion or a non-ionic molecule, composed of a central atom, usually that of a metal, to which is bound a surrounding matrix of other atoms or groups of atoms, each of which is called a binder.

[0079] "Binder" is intended as an atom, ion or molecule which generally donates its electrons, thus acting as a Lewis base, to form a coordination bond. "Bidentate binder" is intended as a chelating binder, i.e., a binder having more than one electron donor atom, which forms two coordination bonds with a metal atom or ion, forming a heterocyclic ring comprising the metal atom or ion.

[0080] "Intermediate product" is intended as a molecular entity, formed starting from reagents, which can react to produce further intermediates or end products of a synthesis.

[0081] "Light-emitting diode (LED)" is intended as an optoelectronic device which exploits the ability of some materials to produce photons through an electro-induced emission phenomenon (called electroluminescence), when crossed by an electric current.

[0082] "Organic light-emitting device (OLED)" is intended as a light-emitting diode (LED), where at least the emissive electroluminescent layer comprises an organic or organometallic compound capable of emitting light in response to an electric current.

[0083] Phosphorescent metal complex

[0084] As described above, an object of the present invention is a phosphorescent metal complex of formula (I), comprising at least one substituted benzofl, 2-b:4, 5- b']dithiophenyl-isoquinolate binder (iqbdt-der): wherein

[0085] M is a metal selected from Ir(III) and Pt(II), m is an integer comprised between 1 and 2,

[0086] L is a bidentate binder and n is an integer comprised between 1 and 2, the sum of n and m is equal to 2 or 3,

[0087] R1is a substituent selected from the group consisting of -H; -F; -CF3; -CN; - CeFs - COOR2and -CONR3R4, preferably selected from the group consisting of -H; -F; -CF3; -CN; - CeFs, preferably selected from -H and -CN,

[0088] R2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls preferably selected from phenyl, 2- methylbenzene, 2,4-dimethylbenzene, 2,4,6-trimethylbenzene, k is the charge of the complex and is equal to 0 or +1, and

[0089] X is an anion, preferably selected from Cl", BFC, or PFe', wherein j is the coefficient of the anion X and is equal to 0 or 1.

[0090] It should be noted that the substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolate binder (iqbdt-der) represented in the structure of formula (I) is characteristic of all the complexes subject to protection, regardless of the nature of the bidentate binder L. The substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolate binder (iqbdt-der) represented in the structure of formula (I) can be defined as a "constant" (bidentate) binder, for the sole purpose of distinguishing it from the ("variable") bidentate binder L.

[0091] According to some embodiments of the invention, the ("variable") bidentate binder structurally coincides with the "constant" (bidentate) binder; in other embodiments of the invention the ("variable") bidentate binder L is structurally different from the" constant" (bidentate) binder.

[0092] It should be noted that the "constant" (bidentate) binder of the metal complex of formula (I) is a corresponding monovalent anion of the substituted benzofl, 2-b:4, 5- b']dithiophenyl-isoquinoline molecule (Hiqbdt-der), characterized by the structure of formula (I5), represented below: The bidentate binder L is preferably selected from 1-phenylpyrazole (ppz), substituted benzofl, 2-b:4,5-b']dithiophene-isoquinoline (Hiqbdt-der) having a structure of formula (I5), substituted P-diketone having a structure of formula (Iis), preferably 2,2,6,6-tetramethyl-3,5-heptanedione (dpm) or 2,4-pentadione (acac), substituted picolinic acid having a structure of formula (I19), substituted bipyridine having a structure of formula (I20), substituted phenanthroline having a structure of formula (I21), or substituted 2-triazolopyridine having a structure of formula (I22):

[0093] Preferably, in the binder L of formula (Iis), R5and R6are independently selected from methyl, tert-butyl, phenyl, trifluoromethyl (-CF3), thiophenyl.

[0094] Preferably, in the binder L of formula (I19), R7is selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CJLCJLO^Me, where i is an integer comprised between 1 and 4.

[0095] Preferably, in the binders L of formula (I20) and (I21), R7and R8are independently selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CJLCJLO^Me, where i is an integer comprised between 1 and 4.

[0096] Preferably, in the binder L of formula (I22), R8is selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CJLCJLO^Me, where i is an integer comprised between 1 and 4. The complex according to the present invention can therefore comprise a total number of substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolate (iqbdt-der) binders of formula (Is), comprised between 1 and 3, preferably equal to 1, 2 or 3.

[0097] According to some embodiments of the complex according to the present invention, k is equal to 0 and j is equal to 0. It should be noted that the complex in accordance with such embodiments contains a non-ionic coordination entity, and can therefore be defined "non-ionic" complex. It should be noted that the non-ionic complex generally lacks a counterion, in particular the anion X, as is obvious to a person skilled in the art.

[0098] According to further embodiments of the complex according to the present invention, k is equal to +1 and j is equal to 1. It should be noted that the complex according to such embodiments contains an ionic, in particular cationic (cation complex), coordination entity, and can therefore be defined "ionic" complex. It should be noted that the ion complex is characterized by the presence of the anion X.

[0099] It should be noted that, preferably, the phosphorescent metal complex, whether it is non-ionic or ionic, i.e., respectively containing a non-ionic or ionic coordination entity, is globally a neutral compound.

[0100] It should be noted that the metal complex of formula (I) is advantageously characterized by an energy difference (Eg) between the frontier molecular orbitals (H0M0-LUM0), expressed in absolute value, of less than 2.40 eV. Preferably, the energy difference (Eg) between the frontier molecular orbitals (H0M0-LUM0), expressed in absolute value, is comprised between about 2.0 and 2.40 eV, preferably between about 2.10 and 2.35 eV, preferably between 2.16 and 2.35 eV.

[0101] The metal complex of formula (I) is advantageously characterized by a near-infrared (Aem) emission wavelength, measured at 298 K, comprised between 700 nm and 900 nm, preferably between 713 and 790 nm, preferably between 728 and 770 nm, preferably equal to 750 nm.

[0102] Still advantageously, the metal complex of formula (I) is characterized by a luminescence quantum efficiency ( L), measured at 298 K, comprised between 0.1 and 15%, preferably comprised between 1 and 6%, preferably comprised between 4 and 5%, preferably comprised between 4.4 and 4.6%, preferably equal to 4.5%. Preferably, such quantum efficiency values are measurable at a near-infrared (NIR) emission wavelength comprised between 700 nm and 900 nm, preferably between 713 and 790 nm, preferably between 728 and 770 nm, preferably equal to 750 nm. Preferably, the metal complex of formula (I) is characterized by a1H NMR spectrum, recorded in a solvent selected from CD2CI2 and CDCh, at an operating frequency equal to 300 MHz, comprising at least one singlet, preferably two singlets, for each substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolate binder (iqbdt-der); such an at least one singlet is identifiable in the spectrum by a relative chemical shift (5) comprised between 6.50 and 9.79 ppm, preferably comprised between 6.91 and 9.79 ppm, preferably comprised between 7.47 and 8.30 ppm, preferably comprised between 7.60 and 8.28 ppm, comprised between 8.13 and 8.26 ppm, preferably equal to 8.13 ppm.

[0103] It should be noted that, preferably, the embodiment of formula (Ii) of the metal complex according to the present invention is characterized by a 'H NMR spectrum comprising two singlets for each substituted benzofl, 2-b:4,5-b']dithiophenyl- isoquinolate binder (iqbdt-der); the two singlets are identifiable in the spectrum by a relative chemical shift (5) comprised between 6.91 and 8.13 ppm.

[0104] It should be noted that, preferably, the embodiment of formula (I2) of the metal complex according to the present invention is characterized by a 'H NMR spectrum comprising two singlets for each substituted benzofl, 2-b:4,5-b']dithiophenyl- isoquinolate binder (iqbdt-der); the two singlets are identifiable in the spectrum by a relative chemical shift (5) comprised between 7.47 and 8.30 ppm.

[0105] It should be noted that, preferably, the embodiment of formula (I3) of the metal complex according to the present invention is characterized by a 'H NMR spectrum comprising two singlets for each substituted benzofl, 2-b:4,5-b']dithiophenyl- isoquinolate binder (iqbdt-der); the two singlets are identifiable in the spectrum by a relative chemical shift (5) comprised between 7.60 and 8.26 ppm.

[0106] It should be noted that, preferably, the embodiment of formula (I4) of the metal complex according to the present invention is characterized by a 'H NMR spectrum comprising two singlets for each substituted benzofl, 2-b:4,5-b']dithiophenyl- isoquinolate binder (iqbdt-der); the two singlets are identifiable in the spectrum by a relative chemical shift (5) comprised between 8.28 and 9.79 ppm.

[0107] Phosphorescent metal complex oflr(III)

[0108] According to a preferred embodiment, the metal complex of formula (I) is a complex of Ir(III), where M is Ir(III) and the sum of m and n is equal to 3.

[0109] Preferably, in the metal complex of Ir(III) of formula (I), the bidentate binder L is preferably a binder selected from: 1-phenylpyrazole (ppz), substituted benzofl, 2- b:4,5-b']dithiophene-isoquinoline (Hiqbdt-der) having the structure of formula (I5), substituted P-diketone having the structure of formula (Iis), preferably 2, 2,6,6- tetramethyl-3,5-heptanedione (dpm) or 2,4-pentadione (acac), substituted picolinic acid having the structure of formula (I19), substituted bipyridine having the structure of formula (I20), substituted phenanthroline having the structure of formula (I21), or substituted 2-triazolopyridine having the structure of formula (I22).

[0110] Preferably, the metal complex of Ir(III) is non-ionic, still preferably it contains the bidentate binder L selected from: 1-phenylpyrazole (ppz), substituted benzofl, 2-b:4, 5- b']dithiophene-isoquinoline (Hiqbdt-der) having the structure of formula (Is), substituted P-diketone having the structure of formula (Iis), preferably 2, 2,6,6- tetramethyl-3,5-heptanedione (dpm) or 2,4-pentadione (acac), substituted picolinic acid having the structure of formula (I19).

[0111] Preferably, the metal complex of Ir(III) is ionic, still preferably it contains the bidentate binder L selected from: substituted bipyridine having the structure of formula (I20), substituted phenanthroline having the structure of formula (I21), 2-triazolylpyridine having the structure of formula (I22).

[0112] According to a preferred embodiment of the non-ionic metal complex of Ir(III), m is equal to 2, the bidentate binder L is substituted P-dichetone having the structure formula (Iis), and n is equal to 1. The complex in accordance with this preferred embodiment has a structure of formula (I23):

[0113] Preferably, in the complex of formula (I23),

[0114] R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and - CONR3R4, and R5and R6are independently selected from methyl, tert-butyl, phenyl, trifluoromethyl (-CF3), thiophenyl.

[0115] Still preferably, in the complex of formula (I23), R1is selected from -H; -F; -CF3; -CN; and -CeFs.

[0116] According to a particularly preferred form, in the complex of formula (I23), R1is -H or -CN.

[0117] In accordance with a first preferred embodiment of the non-ionic metal complex of Ir(III), m is equal to 2, the bidentate binder L is 2,2,6,6-tetramethyl-3,5-heptandione (dpm), n is equal to 1. According to this first embodiment, the non-ionic metal complex of Ir(III) has a structure of formula (Ii):

[0118] Preferably, in the complex of formula (Ii) (or [Ir(iqbdt)2(dpm)]), R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and -CONR3R4.

[0119] Still preferably, in the complex of formula (Ii), R1is selected from -H; -F; -CF3; -CN; and - CeFs.

[0120] According to a particularly preferred form, in the complex of formula (Ii), R1is -H or -CN.

[0121] In accordance with a second preferred embodiment of the non-ionic metal complex of Ir(III), m is equal to 1, L is 1-phenylpyrazole (ppz), n is equal to 2. The complex in accordance with this second embodiment has a structure of formula (I2):

[0122]

[0123] Preferably, in the complex of formula (I2) (or [Ir(iqbdt)(ppz)2]), R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and -CONR3R4.

[0124] Still preferably, in the complex of formula (I2), R1is selected from -H; -F; -CF3; -CN; and - CeFs.

[0125] According to a particularly preferred form, in the complex of formula (I2), R1is -H or -CN.

[0126] In accordance with a third preferred embodiment of the non-ionic metal complex of Ir(III), the bidentate binder L is a substituted benzo[l,2-b:4,5-b']dithiophenyl- isoquinoline (Hiqbdt-der) having structure of formula (I5), and the sum of m and n is equal to 3 (where m and n can be equal to 1 and 2 or 2 and 1, respectively). The complex in accordance with this third embodiment has a structure of formula (I3):

[0127] Preferably, in the complex of formula (I3) (or [Ir(iqbdt)3]), R1is preferably selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and -CONR3R4.

[0128] Still preferably, in the complex of formula (I3), R1is selected from -H; -F; -CF3; -CN; and - CeFs.

[0129] According to a particularly preferred form, in the complex of formula (I3), R1is -H or -CN. According to a fourth preferred embodiment of the non-ionic metal complex of Ir(III), m is equal to 2, the bidentate binder L is substituted picolinic acid having a structure of formula (I19), and n is equal to 1. The metal complex in accordance with this fourth embodiment has a structure of formula (I24):

[0130] Preferably, in the complex of formula (I24),

[0131] R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and - CONR3R4, and

[0132] R7is selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CFFCFFO^Me, where i is an integer comprised between 1 and 4.

[0133] Still preferably, in the complex of formula (I24), R1is selected from -H; -F; -CF3; -CN; and -CeFs. According to a particularly preferred form, in the complex of formula (I24), R1is -H or -CN.

[0134] According to a fifth preferred embodiment of the ionic metal complex of Ir(III), m is equal to 2, the bidentate binder L is substituted bipyridine having a structure of formula (I20), and n is equal to 1. The metal complex in accordance with this fifth preferred embodiment has a structure of formula (I25):

[0135]

[0136] Preferably, in the complex of formula (I25),

[0137] R1is selected from the group consisting of -H; -F; -CF3; -CN; - C6F5 -COOR2and - CONR3R4, R7and R8are independently selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CH2CH2O)Me, where i is an integer comprised between 1 and 4, and

[0138] X is selected from Cl", BFF, PFe’.

[0139] Still preferably, in the complex of formula (I25), R1is selected from -H; -F; -CF3; -CN; and -C6F5.

[0140] According to a particularly preferred form, in the complex of formula (I25), R1is -H or -CN.

[0141] In accordance with a sixth preferred embodiment of the ionic metal complex of Ir(III), m is equal to 2, the bidentate binder L is substituted phenanthroline having a structure of formula (I21), and n is equal to 1. The metal complex in accordance with this sixth preferred embodiment has a structure of formula (I26):

[0142]

[0143] Preferably, in the complex of formula (he),

[0144] R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and - CONR3R4, R7and R8are independently selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CFhCFhO Me, where i is an integer comprised between 1 and 4, and

[0145] X is selected from Cl", BFb, PFe’.

[0146] Still preferably, in the complex of formula (he), R1is selected from -H; -F; -CF3; -CN; and -CeFs.

[0147] According to a particularly preferred form of the complex of formula (he), R1is -H or -CN.

[0148] According to a seventh preferred embodiment of the ionic metal complex of Ir(III), m is equal to 2, the bidentate binder L is substituted 2-triazolylpyridine having a structure of formula (I20), and n is equal to 1. The metal complex in accordance with this seventh embodiment has a structure of formula (I27):

[0149]

[0150] Preferably, in the complex of formula (I27),

[0151] R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and - CONR3R4,

[0152] R8is selected from hydrogen, linear or branched alkyls having from 1 to 3 carbon atoms, phenyl, or (CFFCFFO^Me, where i is an integer comprised between 1 and 4, and

[0153] X is selected from Cl", BFF, PFe’.

[0154] Still preferably, in the complex of formula (I27), R1is selected from -H; -F; -CF3; -CN; and -CeFs.

[0155] According to a particularly preferred form, in the complex of formula (I27), R1is -H or -CN.

[0156] Phosphorescent metal complex ofPt(II)

[0157] According to a preferred embodiment, the metal complex of formula (I) is a complex of Pt(II), where M is Pt(II) and the sum of m and n is equal to 2.

[0158] Preferably, in the metal complex of Pt(II) of formula (I) the bidentate binder L is preferably a binder selected from: substituted P-diketone having the structure of formula (Iis), preferably 2,2,6,6-tetramethyl-3,5-heptandione (dpm) or 2,4- pentanedione (acac), 1-phenylpyrazole (ppz), or substituted benzo[l,2-b:4,5- b']dithiophenyl-isoquinoline (Hiqbdt-der) having a structure of formula (I5).

[0159] In accordance with a preferred embodiment of the non-ionic metal complex of Pt(II), m is equal to 1, the bidentate binder L is 2,2,6,6-tetramethyl-3,5-heptandione (dpm), and n is equal to 1. The complex in accordance with this preferred embodiment has a structure of formula (I4):

[0160]

[0161] Preferably, in the complex of formula (I4) (or [Pt(iqbdt)(dpm)]), R1is selected from the group consisting of -H; -F; -CF3; -CN; - CeFs -COOR2and -CONR3R4.

[0162] Still preferably, in the complex of formula (I4), R1is selected from -H; -F; -CF3; -CN; and - CeFs.

[0163] According to a particularly preferred form, in the complex of formula (I4), R1is -H or -CN.

[0164] Intermediate product for the synthesis of the phosphorescent metal complex

[0165] A further object of the present invention is an intermediate product for the synthesis of the metal complex of formula (I), having a structure selected from that of formula

[0166] (Is), of formula (F) or of formula (I7): wherein

[0167] R1is a substituent selected from the group consisting of: -H; -F; -CF3; -CN; - CeFs; - COOR2; -CONR3R4, and

[0168] R2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls selected from phenyl, 2-methylbenzene, 2,4- dimethylbenzene, 2,4,6-trimethylbenzene.

[0169] In accordance with a preferred embodiment of the intermediate product of formula (I5), R1is selected from -H; -F; -CF3; -CN; and - CeFs, and still preferably R1is -H or -CN.

[0170] Preferably, the intermediate product of formula (I5) is characterized by phosphorescence emission wavelengths (2em,p), measured at 77 K in 2-methyl- tetrahydrofuran, preferably under neutral or acidic pH conditions, comprised between 550 nm and 900 nm, preferably between about 590 nm and 650 nm, still preferably equal to 605 nm or 640 nm.

[0171] It should be noted that neutral pH conditions means that the phosphorescence emission measurement is carried out in solution, where the intermediate product of formula (I5) is dissolved in the solvent as such; acidic pH conditions instead means that the phosphorescence emission measurement is carried out in solution, where the intermediate product of formula (I5) is dissolved in the solvent, in the presence of an organic acid capable of protonating the nitrogen of the isoquinoline ring of the intermediate product of formula (I5).

[0172] The intermediate product in accordance with the present invention is advantageously used in the preparation of the phosphorescent metal complex. The preparation method of the metal complex is disclosed below. Preparation method of the phosphorescent metal complex

[0173] As anticipated above, preparation methods of the phosphorescent metal complex of formula (I), whether it is a complex of Ir (III) or of Pt(II), are also claimed.

[0174] Method for preparing the phosphorescent metal complex oflr(III)

[0175] The method for preparing the phosphorescent metal complex of Ir(III) of formula (I) comprising the steps:

[0176] A. preparing an Ir(III) dimer having two chloride-compounds, the dimer being selected from the intermediate product of formula (le), or a compound having the following structure of formula (Is):

[0177] B. preparing the bidentate binder L, said bidentate binder L preferably being selected from:

[0178] - 2,2,6,6-tetramethyl-3,5-heptanedione (dpm) in the case in which the dimer is the intermediate of formula (le) or the compound of formula (Is), or

[0179] - the intermediate of formula (Is) in the case in which the dimer is the compound of formula (Is);

[0180] C. conducting a binder substitution reaction, reacting the dimer of Ir(III) having two chlorides-compounds with the bidentate binder L, to obtain the phosphorescent metal complex of Ir(III) having the structure of formula (I);

[0181] D. optionally, isolating the phosphorescent metal complex of Ir(III) having the structure of formula (I) and possibly purifying it.

[0182] Preferably, the steps A, B and C are conducted in an inert atmosphere, preferably in an Argon atmosphere.

[0183] According to a preferred embodiment, the step A of preparing an Ir(III) dimer having two chloride compounds comprises the sub-steps:

[0184] Al. preparing the intermediate product of formula (I5); A2. preparing iridium(III) chloride in hydrated form, having the molecular formula IrCh xFFO;

[0185] A3. conducting a Nonoyama19reaction, reacting the intermediate product of formula (I5) with the iridium (III) chloride in hydrated form, to obtain the Ir(III) dimer having two chloride compounds;

[0186] A4. Optionally, isolating the Ir(III) dimer having two chloride compounds and possibly purifying it.

[0187] Preferably, the sub-step Al of preparing the intermediate product of formula (I5), comprises the sub-steps:

[0188] A.1.1. preparing a boronate, preferably a cyclic boronate, of benzofl, 2-b:4, 5- b'] di thiophene, preferably having a structure of formula (I9), of formula (I10), or of formula (In):

[0189] Al.2. preparing a substituted 1-halogen-isoquinoline having a structure of formula (I12) or a substituted N-oxide isoquinoline having a structure of formula (I13): wherein

[0190] X is a halogen, preferably selected from Cl and Br,

[0191] R1is a substituent selected from the group consisting of: -H; -F; -CF3; -CN; - CeFs; - COOR2; -CONR3R4, preferably selected from the group consisting of -H; -F; -CF3; - CN; - GN, preferably selected from -H and -CN, and R2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls selected from phenyl, 2-methylbenzene, 2,4- dimethylbenzene, 2,4,6-trimethylbenzene.

[0192] Al.3. conducting a cross-coupling reaction, reacting benzofl, 2-b:4, 5- b'] di thiophene boronate with the substituted 1-halogen-isoquinoline of formula (I12), or with the substituted N-oxide isoquinoline of formula (I13), to obtain the intermediate product of formula (I5);

[0193] Al.4. optionally, isolating the intermediate product of formula (I5) and possibly purifying it.

[0194] It should be noted that, preferably, the benzofl, 2-b:4,5-b']dithiophene boronate is obtainable by a borylation reaction, which can be carried out by methods known in the art, preferably in the presence of an organometallic compound as activator (e.g., an organolithium, preferably n-BuLi).

[0195] Preferably, the sub-step Al.2 of preparing the substituted isoquinoline N-oxide of formula (I13), comprises the sub-steps:

[0196] Al.2.1. Preparing a substituted isoquinoline, having the following structure of formula (I17): wherein

[0197] R1is a substituent selected from the group consisting of: -H; -F; -CF3; -CN; -CeFs; - COOR2; -CONR3R4, preferably selected from the group consisting of -H; -F; -CF3; - CN; - GN, preferably selected from is -CN, and

[0198] R2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls selected from phenyl, 2-methylbenzene, 2,4- dimethylbenzene, 2,4,6-trimethylbenzene.

[0199] Al.2.2. conducting an N-oxidation reaction, reacting the substituted isoquinoline having the structure of formula (I17) with an organic peroxyacid, preferably meta-chloroperoxybenzoic acid (mCPBA), to obtain the N-oxide- substituted isoquinoline having the structure of formula (I13); Al.2.3. optionally, isolating the substituted isoquinoline N-oxide of formula (IB) and possibly purifying it.

[0200] Preferably, the sub-step Al.2.2 is conducted in organic solvent, preferably dichloromethane (DCM).

[0201] According to a preferred embodiment of the sub-step Al for preparing the intermediate product of formula (Is), the cross-coupling reaction of sub-step Al.3 is a Suzuki condensation20.

[0202] According to an alternative embodiment of the sub-step Al for preparing the intermediate product of formula (I5), the sub-step A.1.3 for conducting a condensation reaction can be carried out in the absence of catalyst. In such a case, the sub-step Al.3 comprises the sub-steps:

[0203] Al.3.1 '. preparing a catalyst-free solution comprising a mixture of benzofl, 2- b:4,5-b']dithiophene boronate and substituted isoquinoline N-oxide of formula (I13), preferably in a molar ratio of 1 :3 respectively, preferably in dimethyl sulphoxide (DMSO) as solvent;

[0204] Al.3.2'. heating the catalyst-free solution, keeping it under stirring, at a temperature of 110°C, for a time equal to about 16 hours, to obtain the intermediate product of formula (I5);

[0205] Al.3.3'. cooling the catalyst-free solution heated to room temperature, until reaching room temperature.

[0206] Preferably, the solution cooling sub-step Al.3.3' comprises a further dilution sub-step of the cooled solution by the addition of water, preferably in a volumetric ratio comprised between 3: 1 and 20: 1, preferably equal to 10: 1 with respect to the volume of dimethyl sulphoxide (v / v).

[0207] According to a preferred embodiment, the sub-step A3 of conducting a Nonoyama reaction19comprises the sub-steps:

[0208] A3.1. preparing a solution comprising a mixture of the intermediate product of formula (I5), and of the reagent iridium (III) chloride in hydrated form, preferably in molar ratios respectively equal to about 2.5: 1, preferably using a mixture of 2- ethoxy ethanol H2O as solvent, preferably in a volumetric ratio preferably equal to about 3: 1; A3.2. heating the solution to a temperature comprised between 110 and 130°C, preferably 120°C, for a time comprised between 7 and 16 hours, preferably equal to 16 hours;

[0209] A3.3. cooling the reaction solution to room temperature.

[0210] Preferably, the step C of conducting a binder substitution reaction is conducted at a temperature equal to or greater than 100°C, preferably comprised between 100 and 250°C, using 2-ethoxyethanol as solvent, in the presence of potassium or sodium carbonate, or glycerol as a solvent.

[0211] It should be noted that the activities of isolation and possible purification of the final products or of the intermediate reaction products can be conducted by a person skilled in the art using methodologies known in the state of the art. By way of non-limiting example, the isolation of the product of interest can be carried out using extraction, filtration, drying techniques, etc.; the purification of the product of interest can be carried out with column chromatography techniques.

[0212] Method for preparing the phosphorescent metal complex ofPtfll)

[0213] A further object of the present invention is a method for preparing the phosphorescent metal complex of Pt(II) of formula (I), comprising the steps:

[0214] E. preparing the intermediate product of formula (I7);

[0215] F. preparing the bidentate binder L, preferably 2,2,6,6-tetramethyl-3,5-heptanedione (dpm);

[0216] G. conducting a binder substitution reaction, reacting the intermediate product of formula (I7) with the bidentate binder L, to obtain the phosphorescent metal complex ofPt(II);

[0217] H. isolating the phosphorescent metal complex of Pt(II) and possibly purifying it, to obtain a pure complex.

[0218] Preferably, steps E, F, and G are conducted in an inert atmosphere, preferably in an Argon atmosphere.

[0219] According to a preferred embodiment of the synthesis method of the metal complex of Pt(II) in accordance with the formula (I), the step E of preparing the intermediate product of formula (I7), comprises the sub-steps:

[0220] El. preparing the intermediate product of formula (I5); E2. preparing potassium tetrachloroplatinate(II), having molecular formula K2PtCl4;

[0221] E3. reacting the intermediate product of formula (Is) with potassium tetrachloroplatinate(II) to obtain the intermediate product having a structure of formula ( ).

[0222] It should be noted that, preferably, the step El of preparing the intermediate product of formula (I5) in accordance with the method for preparing the phosphorescent metal complex of Pt(II) of formula (I) is the same as the step Al of preparing the intermediate product in accordance with the preparation method of the phosphorescent metal complex of Ir(III) of formula (I).

[0223] According to a preferred embodiment of step E of preparing the intermediate product of formula (I7), the sub-step E3 is an oxidative addition / reductive elimination reaction, conducted according to techniques known to a person skilled in the art.

[0224] Preferably, the step G of conducting the binder substitution reaction is conducted under the same conditions as step C of the method for preparing the phosphorescent metal complex of Ir(III) of formula (I). Preferably, the step G of conducting a binder substitution reaction is conducted at a temperature equal to or greater than 100°C, preferably equal to 100°C, preferably using 2-ethoxy ethanol as a solvent, in the presence of potassium or sodium carbonate.

[0225] Organic solid-state optoelectronic device

[0226] A further object of the present invention is the use of the phosphorescent metal complex of formula (I) in (organic) light-emitting solid-state optoelectronic devices, preferably selected from organic light-emitting diodes (OLEDs), organic lightemitting transistors (OLETs) or electrochemical light-emitting cells (LECs or LEECs), still preferably OLEDs.

[0227] In other words, a further object of the present invention is an (organic) light-emitting solid-state optoelectronic device comprising: at least two electrodes; and an active layer, comprising the phosphorescent complex having the structure of formula (I). PLED

[0228] According to a preferred embodiment, the light-emitting optoelectronic device is an OLED. In accordance with such an embodiment, the optoelectronic light-emitting device is characterized in that it comprises: at least two electrodes, and preferably two electrodes, of which one consists of an anode element and one consists of a cathode element; an active layer, arranged between the anode element and the cathode element, comprising the complex having the structure of formula (I), and, preferably, a support (or substrate) layer, useful for ensuring structural support to the other layers of the device. By way of example, materials useful for making the support layer are glass, metal or plastic materials, biopolymers.

[0229] It should be noted that, preferably, the anode element is included in or constitutes an anode layer of the OLED device; similarly, the cathode element is included in or constitutes a cathode layer of the OLED device.

[0230] According to a preferred embodiment of the optoelectronic device in OLED form, the active layer comprising the complex having the structure of formula (I), a material for transporting holes, and an electron transport material.

[0231] Preferably, the hole-transport material is a conjugate compound selected from the group consisting of: polyvinylcarbazole (PVK), 4, 4'-Bis(N-carbazolyl)- 1,1 '-biphenyl (CBP), 2,2',2"-(l,3,5-Benzonitrile)-tris(l-phenyl-l-H-benzimidazole) (TPBi), preferably PVK.

[0232] Electron transport materials suitable for making the OLED of interest are preferably selected from: l,3-bis(5-4-tert-butylphenyl)-l,3,4-oxadiazol-2-yl)benzene (0XD7), oxadiazole derivatives.

[0233] According to a first embodiment, the at least one active layer preferably comprises

[0234] - an emissive layer (or emitter) comprising or consisting of the phosphorescent metal complex of formula (I)

[0235] - a layer comprising or consisting of the hole transport / inj ection material (HTL)

[0236] - a layer comprising or consisting of the electron transport / inj ection material (ETL).

[0237] In accordance with this first embodiment, the optoelectronic device in the form of OLEDs preferably also comprises a polymeric layer consisting of a mixture of ionomers, where a suitable mixture of ionomers is, for example, poly(3,4- ethylenedi oxy thiophene) doped with poly(styrene sulphonate) (otherwise called PEDOT:PSS). Still preferably, the polymer layer is adjacent to the anode layer and the emissive layer is adjacent to the cathode layer.

[0238] In accordance with this first embodiment, the polymer layer is preferably adjacent to the anode layer, the hole transport / inj ection layer is adjacent to the polymer layer and to the emissive layer, the electron transport / inj ection layer is adjacent to the emissive layer and to the cathode layer, the emissive layer is interposed between the hole transport / inj ection layers and the electron transport / inj ection layer.

[0239] According to a second embodiment, the at least one active layer comprises or consists of an emissive (or emitter) layer comprising or consisting of a mixture of the holetransport material, the phosphorescent metal complex of formula (I) and the electron transport material.

[0240] Also in this second embodiment, the optoelectronic device in the form of OLEDs can comprise a polymeric layer consisting of a mixture of ionomers, where a suitable mixture of ionomers is, for example, poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulphonate) (otherwise called PEDOT:PSS).

[0241] In accordance with this second embodiment, the polymer layer is adjacent to the anode layer and the emissive layer is adjacent to the cathode layer.

[0242] Preferably, the phosphorescent complex of formula (I) suitable for the preparation of the emissive layer is selected from:

[0243] - the metal complex of Ir(III) in accordance with the formula (I), and preferably in accordance with any one of formulae (Ii), (I2) or (E); and

[0244] - the metal complex of Pt(II) in accordance with the formula (I), and preferably in accordance with the formula (I4). The most preferred complexes for the purpose of making the OLED are the metal complexes of formula (I2) or (I4).

[0245] Preferably, the emissive layer includes the metal complex of formula (I) in an amount comprised between about 1% and 10%, preferably between about 4% and 8%, preferably equal to about 5% by weight on the total weight of the emissive layer (w / w).

[0246] Preferably, the emissive layer includes the hole-transport material in an amount comprised between about 50% and 80%, preferably between about 57% and 70%, preferably equal to about 65% by weight of the total weight of the emissive layer (w / w). Preferably, the emissive layer includes the electron transport material in an amount comprised between about 19% and 40%, preferably between about 26% and 35%, preferably equal to about 35% by weight on the total weight of the emissive layer (w / w).

[0247] The support layer can be adjacent to the anode layer ("direct-structure OLED") or to the cathode layer ("inverted-structure OLED"). Preferably, the optoelectronic device in the form of OLED in accordance with the present invention is a direct-structure OLED.

[0248] Preferably, in the optoelectronic device in the form of a direct-structure OLED, the cathode layer consists of at least one metal layer, where said metal layer preferably comprises or consists of aluminium (Al).

[0249] According to a further preferred embodiment, in the optoelectronic device in the form of a direct-structure OLED, the cathode layer consists of two metal layers, of which one is superficial, and one is internal (i.e., adjacent to the other layers constituting the OLED). Preferably, the surface metal layer consists of aluminium (Al) or silver (Ag) and the inner metal layer comprises or consists of barium (Ba), calcium (Ca), or a salt, preferably lithium fluoride (LiF). The more preferred embodiment envisages that the cathode layer of the direct-structure OLED consists of an inner metal layer of barium (Ba) and an outer metal layer of aluminium (Al).

[0250] Preferably, in the optoelectronic device in the form of a direct-structure OLED, the anode layer consists of a material selected from the group consisting of: tin-doped indium oxide (ITO), fluorine-doped indium oxide (FIX)), aluminium-doped zinc oxide (AZO), indium-gallium-zinc oxide (IGZO), gallium-zinc oxide (GZO), preferably ITO

[0251] Preferably, the polymer layer has a thickness comprised between about 10 nm and 100 nm, preferably equal to about 50 nm; the emissive layer has a thickness comprised between about 30 nm and 250 nm, preferably equal to about 200 nm; the electron transport layer has a thickness comprised between about 5 nm and 50 nm, preferably equal to about 20 nm; and the hole transport layer has a thickness comprised between about 5 nm and 50 nm, preferably equal to about 35 nm.

[0252] Preferably, the OLED obtainable using the phosphorescent metal complex of formula (I) can advantageously achieve external quantum efficiency (EQE) values between 0.5% and 5%, preferably equal to about 0.5%. It should be noted that, advantageously, the OLED can find application in numerous technical fields, including the following sectors: smart building (safety sensors, active surveillance sensors, proximity sensors);

[0253] - telecommunications; medical diagnostics (medical sensors) and photodynamic therapies; automotive driving safety (infrared sensors); nanotechnologies.

[0254] OLET

[0255] According to a preferred embodiment, the light-emitting optoelectronic device is an OLET. In accordance with such an embodiment, the optoelectronic light-emitting device is characterized in that it comprises: at least two electrodes, preferably three electrodes, including a "drain" electrode, a "source" electrode and a "gate" electrode an organic semiconductor layer, comprising or consisting of the phosphorescent complex of formula (I) a dielectric layer, comprising or consisting of an insulating material.

[0256] The gate electrode preferably comprises or consists of a metal or a transparent conductive oxide. The optical transparency in the visible range or NIR allows the light to be extracted also through such an electrode.

[0257] Suitable materials for making the gate electrode of the optoelectronic device in the form of an OLET include: indium-tin-oxide (ITO), aluminium-doped zinc oxide (AZO), indium-gallium-zinc oxide (IGZO), and gallium-zinc oxide (GZO).

[0258] The source and drain electrodes preferably consist of metal films with appropriate working function to allow an efficient charge injection into the organic semiconductor layer. The organic layer is the active part of the device, where charge transport and light emission occur. This layer can be characterized by a mono-layer or multi-layer structure.

[0259] The dielectric layer electrically insulates the gate from the source and drain electrodes and is necessary for the field effect to take place and be able to induce polarization at the interface to allow transport into the active organic layer. LEEC

[0260] According to a preferred embodiment, the light-emitting optoelectronic device is a LEEC. In accordance with such an embodiment, the optoelectronic light-emitting device is characterized in that it comprises: at least two electrodes, and preferably two electrodes, of which one consists of an anode element and one consists of a cathode element, a conductive layer comprising or consisting of a transparent conductive material arranged between the anode element and the cathode element; an active layer comprising the phosphorescent metal complex having the structure of formula (I), arranged between the anode element and the cathode element, preferably adjacent to the cathodic element; and, preferably, a support (or substrate) layer, useful for ensuring structural support to the other layers of the device. By way of example, materials useful for making the support layer are glass, metal or plastic materials, biopolymers.

[0261] It should be noted that, preferably, the anode element is included in or constitutes an anode layer of the LEEC device, said anode layer preferably being transparent; similarly, the cathode element is included in or constitutes a cathode layer of the LEEC device.

[0262] The materials most commonly used to make transparent anode layers for LEECs include, for example, indium tin oxide (ITO), aluminium-doped zinc oxide (AZO), indium-gallium-zinc oxide (IGZO), gallium-zinc oxide (GZO).

[0263] According to a preferred embodiment of the optoelectronic device in the form of LEECs, the active layer comprising the complex having the structure of formula (I) and an ionic electrolyte; preferably the active layer also comprises a hole-transport material.

[0264] According to an alternative embodiment, the at least one active layer preferably comprises

[0265] - an emissive layer (or emitter) comprising a mixture of the phosphorescent metal complex of formula (I) and an ionic electrolyte;

[0266] - a layer comprising or consisting of the hole-transport material (HTL), where the HTL layer is arranged between the emissive layer and the anode layer, and preferably the HTL layer is adjacent to the emissive layer and the anode layer. Preferably, the hole-transport material consists of mixtures of ionomers, such as poly(3,4-ethylenedi oxythiophene) doped with poly(styrene sulphonate) (PEDOT:PSS).

[0267] EXAMPLES

[0268] By way of non-limiting example, some examples of synthesis and characterization of the complex(es) according to the present invention are given below.

[0269] EXAMPLE 1: Synthesis and characterization of benzo[l,2-b:4,5-b']dithiophene, 2-(4,4,5,5-tetramethyl-l,3,2-dioxaborolane-2-yl) (bdt-Bor)

[0270] The synthesis method of benzofl, 2-b:4,5-b']dithiophene, 2-(4,4,5,5-tetramethyl-l,3,2- dioxaborolane-2-yl) (bdt-Bor) is shown below, which can be summarized according to the following reaction diagram:

[0271] 1 ) n-BuLi

[0272] In an argon atmosphere, 1 eq. of benzofl, 2-b:4,5-b']dithiophene (500 mg, 2.63 mmol) is dissolved in 13 mL of anhydrous THF. After cooling to -78°C, 1.25 eq. of n-BuLi (2.0 mL, 1.4 M in hexane) was poured into the solution and the mixture was left at - 78°C for 1 hour. When the solution turned yellowish, 1.15 eq. (0.62 mL, 3.02 mmol) of 2-isopropoxide-4,4,5,5-tetramethyl-l,3,2-dioxaborolane were added in drops and left to react for 1 hour. After warming to room temperature, NH4CI (10 mL) was added to the reaction mixture and the organic phase was extracted with CH2CI2 three times. The product was subsequently dried under high-pressure vacuum to obtain 81% of yellow-brown solid, usable in subsequent reactions without further purification.

[0273] The product was characterized by3H NMR and13C NMR, the results of which are shown below.

[0274] 'H-NMR (CDCh, 300 MHz, 5 ppm): 8.35 (s, 1H), 8.33 (s, 1H), 7.92 (s, 1H), 7.48 (d, 1H, J = 5.5 Hz), 7.35 (d, 1H, J = 5,5 Hz), 1.40 (s, 12H).

[0275] °C-NMR (Cdis, CDCh, 300 MHz, 5 ppm): 140.77, 138.47, 138.41, 137.07 (Cq arom), 133.60, 127.82, 122.91, 117.16, 116.70 (CH arom), 84.48 (Cq), 24.81 (CH3). EXAMPLE 2: Synthesis and characterization of the intermediate 2-(benzo[l,2- b:4,5-b']-dithiophene) isoquinoline (Hiqbdt)

[0276] The synthesis method of the intermediate 2-(benzo[l,2-b:4,5-b']dithiophene) isoquinoline (Hiqbdt) by Suzuki condensation reaction20is shown below, which can be summarized according to the following reaction diagram:

[0277] In a nitrogen gas atmosphere, 1 eq. of Benzofl, 2-b:4,5-b']dithiophene, 2-(4, 4,5,5- tetramethyl-l,3,2-dioxaborolane-2-yl) (800 mg, 2.51 mmol), prepared for example according to the method shown in EXAMPLE 1, 1.05 eq of 1 -bromoisoquinoline (550 mg, 2.64 mmol), 5 eq. of K2CO3 (1.75 g, 12.65 mmol) and 0.05 eq. of tetrakis(triphenylphosphine) palladium (145 mg, 0.126 mmol) were dissolved in a mixture of 15 mL of THF and 15 mL of H2O.

[0278] The solution was degassed for 15 minutes, bubbling N2, and heated to 60°C, in an inert atmosphere, for 6 hours. The reaction was checked with TLC. After cooling to room temperature, a saturated NaCl solution was added to the reaction mixture, and the organic phase was extracted with CH2Q2 three times. The product was subsequently filtered over 3CaO AI2O3 and purified by silica column chromatography using hexane / ethyl acetate 8: 1 to remove the unreacted materials, then passed through with hexane / ethyl acetate / CHjCb 8: 1 :4 and then finally with pure CH2Q2 to completely recover the product with a 92% yield.

[0279] The product was characterized by liquid chromatography-mass spectrometry (LC-MS) and 'H NMR, and photochemical characterization (absorption spectrum and emission spectrum), the results of which are shown below.

[0280] LC-MS: retention time (tR) = 2.136 min, purity > 98.5% ; MW 318.2 [M+H]+, 657.1 [2M+Na]+.

[0281] 'H-NMR (CDCh, 300 MHz, 5 ppm): 8.70 (d, 1H, J = 9.4 Hz), 8.65 (d, 1H, J = 5.7 Hz), 8.41 (s, 1H), 8.37 (s, 1H), 7.97 (s, 1H), 7.95 (d, 1H, J = 9.0 Hz), 7.79 (t, 1H, J = 7.5 Hz), 7.71 (m, 1H), 7.70 (d, 1H, J = 5.70 Hz), 7.53 (d, 1H, J = 5.5 Hz), 7.40 (d, 1H, J = 5.5 Hz). In Figure 2, the absorption curves, at RT in CH2CI2), at neutral / basic pH and at acidic pH, and the emission curves (RT in CH2CI2) of Hiqbdt at neutral / basic pH and at acidic pH and the emission curve at 77 K in 2-MeTHF are shown in a single graph.

[0282] Below, in Table 1, the photo-physical properties of Hiqbdt are reported in CH2Q2 solutions (CM = 2- 10'5mol L'1) at 298 K and in 2-MeTHF solution at 77 K, obtained from the absorption and emission curves shown in Figure 2.

[0283] Table 1 : Photo-physical properties of Hiqbdt in CH2CI2 solutions (CM = 2 10~5mol-L~ f at 298 K and 77 K in 2-MeTHF.

[0284] It should be noted that neutral pH means that the phosphorescence emission measurement is conducted in solution, in which the intermediate produced Hiqbdt has been dissolved in the solvent as such; acidic pH means that the phosphorescence emission measurement is conducted in solution, in which the intermediate product Hiqbdt has been dissolved in the solvent, in the presence of an organic acid capable of protonating the nitrogen of the isoquinoline ring of the intermediate product of formula (Is); lastly, basic pH means that the phosphorescence emission measurement is conducted in solution, in which the intermediate product Hiqbdt has been dissolved in the solvent, in the presence of a basic substance capable of maintaining the nitrogen of the isoquinoline ring in deprotonated form.

[0285] The radiative krand non-radiative kmvelocity constants are calculated with the equations kr= L / T and km= 1 / T -kr, assuming that isc = 1. EXAMPLE 3: Synthesis of the intermediate dimer of Ir(III), [(iqbdt)2lrCl]2

[0286] The synthesis method of the intermediate benzofl, 2-b:4,5-b']dithiophene, 2-(4, 4,5,5- tetramethyl-l,3,2-dioxaborolane-2-yl) (bdt-Bor) is shown below, by Nonoyama reaction19, which can be summarized according to the following reaction diagram:

[0287] 1 eq. of IrCh wEhO (150 mg, 0.50 mmol) and 2.3 eq. of 2-(benzo[l,2-b:4,5- b'] di thiophene) isoquinoline (Hiqbdt) (366 mg, 1.16 mmol), prepared for example according to the method shown in EXAMPLE 2, were heated to 120°C in a 3 : 1 mixture of 2-ethoxyethanol (12 mL) and water (4 mL) overnight. After cooling to room temperature, water (30 mL) was added to the reaction mixture, which was filtered and the solid was washed thoroughly with water and then ethyl ether and hexane, and dried under high-pressure vacuum to obtain 90% of f(iqbdt)2lrCl]2 (390 mg), usable in the subsequent reactions without further purification.

[0288] EXAMPLE 4: Synthesis of the intermediate of Pt(II), f(iqbdt)2PtCl]

[0289] The synthesis method of the intermediate f(iqbdt)2PtCl] is shown below, which can be summarized according to the following reaction diagram:

[0290] In an argon atmosphere, 1 eq. ofK^PtCh (63 mg, 0.152 mmol) and 2.1 eq. of 2-(Benzo [l,2-b:4,5-b] dithiophene) isoquinoline, (Hiqbdt) (100 mg, 0.315 mmol), prepared for example according to the method shown in EXAMPLE 2, were heated at 80°C in a 3 : 1 de-aerated mixture of 2-ethoxyethanol (4.5 mL) and water (1.5 mL) overnight. After cooling to room temperature, water (3 mL) was added to the reaction mixture, it was filtered and the solid was washed thoroughly with water followed by isopropanol, ethyl ether and hexane, and dried under high-pressure vacuum to obtain 90% of [(iqbdt)2PtCl] (122 mg), usable in subsequent reactions without further purification.

[0291] EXAMPLE 5: Synthesis of the intermediate dimer of Ir(III), [(ppz)2lrCl]2

[0292] The synthesis method of the intermediate [(ppz)2lrCl]2 by Nonoyama reaction19is shown below, which can be summarized according to the following reaction diagram:

[0293] 1 eq. of IrCh / / H2O (391 mg, 1.24 mmol) and 2.5 eq. of 1-phenylpyrazole (ppzH) (500 mg, 3.10 mmol) were heated at 120°C in a 3: 1 mixture of 2-ethoxyethanol (18 mL) and water (9 mL) overnight. After cooling to room temperature, water (30 mL) was added to the reaction mixture, the suspension was filtered and the solid was thoroughly washed with water followed by ethyl ether and hexane and dried under high-pressure vacuum to obtain 80% [(ppz)2lrCl]2 (509 mg), usable in subsequent reactions without further purification.

[0294] EXAMPLE 6: Synthesis and characterization of the complex of Ir(III), [Ir(iqbdt)(ppz)2]

[0295] The synthesis method of the complex [Ir(iqbdt)(ppz)2] by binder substitution reaction is shown below, which can be summarized according to the following reaction diagram:

[0296] In an argon atmosphere, 1 eq. of [(ppz)2lrCl]2 (100 mg, 0.098 mmol), prepared for example according to the method shown in EXAMPLE 5, 2.5 eq. of 2-(Benzo [1,2- b:4,5-b] dithiophene) isoquinoline binder, (Hiqbdt) (77.4 mg, 0.245 mmol), prepared for example according to the method shown in EXAMPLE 2, and 10 eq. of sodium carbonate (103.4 mg, 0.976 mmol) were dissolved in 2-ethoxyethanol (15 mL) and heated at 120°C for 12 hours. The reaction was checked with TLC. After the reaction mixture had cooled to room temperature, water (30 mL) was added to the reaction mixture and filtered. The solid was washed thoroughly with water and then with isopropanol and ethyl ether. The crude result (135 mg) was purified by flash column chromatography using CH2CI2 / 1T1 ethanol 95:5 to remove the binder, obtaining 48.7 mg of pure product of [Ir(iqbdt)(ppz)2] (31% yield).

[0297] The product was characterized by electrospray mass spectrometry (MS-ESI) andTH NMR, the results of which are shown below. In this regard, it should be noted that theTH NMR spectrum, the relative expansion and the COSY-NMR spectrum, for the complex [Ir(iqbdt)(ppz)2], are shown in figures 3, 4 and 5, respectively.

[0298] MS-ESI: m / z = 796 [M+H]+.

[0299] 'H-NMR (CD2CI2, 300 MHz, 5 ppm): 9.21 (d, J= 8.3 Hz, 1H), 8.30 (s, 1H), 8.11 (d, J = 6.2 Hz, 1H), 8.01 (t, J = 2.9 Hz, 2H), 7.84 - 7.63 (m, 4H), 7.47 (s, 1H), 7.33 (td, J = 13.5, 5.5 Hz, 4H), 7.19 - 7.02 (m, 4H), 6.97 (t, J = 7.1 Hz, 1H), 6.91 (t, J= 7.4 Hz, 1H), 6.68 (d, J= 7.0 Hz, 1H), 6.53 (d, J= 7.4 Hz, 1H), 6.36 (t, J= 2.5 Hz, 1H), 6.26 (t, J= 2.5 Hz, 1H).

[0300] EXAMPLE 7: Synthesis and characterization of the complex of Ir(III), [Ir(iqbdt)2(dpm)J

[0301] The synthesis method of the complex [Ir(iqbdt)2dpm] by binder substitution reaction is shown below, which can be summarized according to the following reaction diagram:

[0302] In an argon atmosphere, 1 eq. of [(iqbdt)2lrCl]2 (150 mg, 0.09 mmol), 2.5 eq. of 2,2,6,6-Tetramethyl-3,5-heptanedione (Hdpm) binder (40.15 mg, 45.2 pl, 0.21 mmol) and 9 eq. of potassium carbonate (108.4 mg, 0.79 mmol) were dissolved in 2- ethoxyethanol (15 mL) and heated at 120°C for 12 hours. The reaction was checked with TLC. After the reaction mixture had cooled to room temperature, water (30 mL) was added to the reaction mixture and filtered. The solid was dissolved in CH2Q2 and the organic phase was washed with water. The solvent was removed under high- pressure vacuum and the crude residue was treated with ethyl ether to remove the unreacted dimer. After removal of the solvent (67 mg), the extract was purified by flash column chromatography using ChbCb / hexane 2:3 to remove the binder and then again ethyl acetate / hexane 2:3 to obtain 16 mg of pure [Ir(iqbdt)2dpm] (10% yield).

[0303] The product was characterized by1H NMR, the results of which are shown below. In this regard, it should be noted that theTH NMR spectrum, the relative expansion and the COSY-NMR spectrum, for the complex [Ir(iqbdt)2dpm], are shown in figures 7, 8 and 9, respectively.

[0304] 'H-NMR (CDCh, 300 MHz, 5 ppm): 9.06 (d, 2H, J = 8.57 Hz), 8.23 (d, 2H , J = 6.40 Hz), 8.13 (s, 2H), 7.94 (m, 2H), 7.78 (m, 4H), 7.31 (d, 2H, J = 6.24 Hz), 7.21 (d, 2H, J = 5.39 Hz), 7.15 (d, 2H, J = 5.45), 6.91 (s, 2H), 5.50 (s, 1H), 1.55 (s, 9H), 1.26(s, 9H).

[0305] EXAMPLE 8: Synthesis of the complex of Ir(III), [Ir(iqbdt)3]

[0306] The synthesis method of the complex [Ir(iqbdt)s] by binder substitution reaction is shown below, which can be summarized according to the following reaction diagram:

[0307] In an Argon atmosphere, 1 eq. of [(iqbdt)2lrCl]2 (50 mg, 0.03 mmol), prepared for example according to the method shown in EXAMPLE 3, and 3.9 eq. of 2-(Benzo [l,2-b:4,5-b] dithiophene) isoquinoline binder (Hiqbdt) (35.9 mg, 0.11 mmol), prepared for example according to the method shown in EXAMPLE 2, in 8 mL of glycerol, were heated overnight at 250°C. After cooling the reaction mixture to room temperature, water (20 mL) was added to the reaction mixture, which was filtered, and the filtered solid was washed thoroughly with water followed by isopropanol, ethyl ether, and hexane until complete removal of the unreacted Hiqbdt. The crude product (65 mg) was purified by flash column chromatography using CH2Q2 as eluent to obtain 14 mg (21% yield) of [Ir(iqbdt)3] .

[0308] The product was characterized by electrospray mass spectrometry (MS-ESI) andTH NMR, the results of which are shown below. In this regard, it should be noted that theTH NMR spectrum, the relative expansion and the COSY-NMR spectrum, for the complex [Ir(iqbdt)3], are shown in figures 11, 12 and 13, respectively.

[0309] 1H-NMR (CDC13, 300 MHz, 5 ppm): 9.12 (d, 3H, J = 8.7 Hz), 8.26 (s, 3H), 7.70-7.55 (m, 12H), 7.31 (d, 3H, J = 6.20 Hz), 7.21 (d, 3H, J = 5.45 Hz), 7.17 (d, 3H, J = 5.45 Hz), 7.02 (d, 3H, J = 6.20 Hz)

[0310] MS-ESI, tR = 5.8 min; m / z = 1142.7 [M+H]+; M2(l 142.7) = 824.7 [M-iqbdt]

[0311] EXAMPLE 9: Synthesis of the complex of Pt(II), [Pt(iqbdt)(dpm)J

[0312] The synthesis method of the complex [Pt(iqbdt)(dpm)] is shown below, which can be summarized according to the following reaction diagram:

[0313] In an argon atmosphere, 1 eq. of [(iqbdt)2PtCl] (100 mg, 0.12 mmol), prepared for example according to the method shown in EXAMPLE 4, 3 eq. of 2,2,6,6-tetramethyl- 3, 5 -heptanedi one (Hdpm) binder (63.96 mg, 73.4 pl, 0.35 mmol) and 10 eq. ofNa2CO3 (122.62 mg, 1.16 mmol) in 6 mL of 2-ethoxyethanol were heated overnight at 100°C. After the reaction mixture was cooled to room temperature, water (8 mL) was added to the reaction mixture, filtered, and the solid was washed thoroughly with water followed by ethyl ether and hexane. The crude product (101 mg) was purified by flash column chromatography using CFLCb / hexane 6:4 as an eluent to obtain 31 mg (39% yield) of [Pt(iqbdt)dpm],

[0314] The product was characterized by3H NMR, the results of which are shown below. In this regard, it should be noted that the3H NMR spectrum, the relative expansion and the COSY-NMR spectrum, for the complex [Pt(iqbdt)(dpm)], are shown in figures 15, 16 and 17, respectively.

[0315] 'H-NMR (CDC13, 300 MHz, 5 ppm): 9.79 (s, 1H), 9.00 (d, 1H, J = 6.63 Hz), 8.81 (d, 1H, J = 8.23 Hz), 8.28 (s, 1H), 7.71 (m, 3H), 7.51 (d, 1H, J = 5.50 Hz), 7.37 (d, 1H, J = 5.51 Hz), 7.32 (d, 1H, J = 6.60 Hz), 5.98 (s, 1H), 1.46 (s, 9H), 1.36 (s, 9H).

[0316] The complexes [Ir(iqbdt)(ppz)2], [Ir(iqbdt)2dpm], [Ir(iqbdt)3], [Pt(iqbdt)(dpm)], obtained by the methods shown in EXAMPLES 6, 7, 8, and 9, respectively, were characterized spectroscopically.

[0317] The spectroscopic properties, summarized below in Table 2a and 2b, were derived from the absorption and emission spectra of the aforesaid complexes. Such absorption and emission spectra are represented for each of said complexes in Figures 6, 10, 14 and 18, respectively.

[0318] Table 2a

[0319] Absorption Emission 298 K[a]

[0320] Aabs AT Anr

[0321] Complex m (105s-1) (105s-1)

[0322] 272 (18.05), 338

[0323] (11.35), 408 (4.67), 562,

[0324] Pt(iqbdt)dpm 0.641 <1.0 0.16 15.4

[0325] 520 (7.15), 658 750

[0326] 338, (25.12), 369

[0327] (16.85) [sh], 435

[0328] Ir(iqbdt)(ppz)2 (9.06) [sh], 458 713 1.50 4.6 0.31 6.36

[0329] (12.05), 509 (9.32) 302, (32.14), 343

[0330] (24.74), 383

[0331] (18.43), 425

[0332] Ir(iqbdt)2dpm

[0333] (161.9), 465 (8.70),

[0334] 750 0.746 0.60 12.8 546 [broad] (8.77), 662, (0.29), 725

[0335] 267, (59.45), 299

[0336] (33.93), 337

[0337] (47.89), 366

[0338] (32.99) [sh], 384

[0339] Ir(iqbdt)3(21.64) [sh], 448 728 1.39 5.4 0.39 6.81

[0340] (23.98) [sh], 476

[0341] (31.05), 537

[0342] (14.87), 645 (0.35),

[0343] Table 2b

[0344] Emission 77 K / h ] Electrochemical [c] λem HOMO LUMO EgEC

[0345] Complex r (μs)

[0346] (nm) (eV) (eV) (eV)

[0347] 0.91 (@735nm)

[0348] 538 5.36 ns

[0349] Pt(iqbdt)dpm

[0350] 733 (@540nm)

[0351] Ir(iqbdt)(ppz)2 698 1.80

[0352] Ir(iqbdt)2dpm 732 1.34 -5.04 -2.91 2.16 ()

[0353] [d]

[0354] 2.29 ()

[0355] Ir(iqbdt)3715 1.70 -5.14 -2.85

[0356] [d]

[0357] Table 2a / 2b: Summary of spectroscopic properties of the complexes [Ir(iqbdt)(ppz)2], fhfiqbdtfdpm], [Ir(iqbdt)3], [Pt(iqbdt)(dpm)]. EXAMPLE 10: Synthesis of the compound 4CN-iQ-NO

[0358] The synthesis method of an N-oxide substituted isoquinoline, in particular 4CN-iQ- NO, by N-oxidation reaction is shown below, which can be summarized according to the following reaction diagram:

[0359] 3 -chloroperbenzoic acid (1.3 mmol) was added to a solution of 4CN-iQ (1 mmol) in di chloromethane (10 mL), and the reaction was stirred for 24 hours at room temperature. Subsequently the residual 3 -chloroperbenzoic acid was removed by adding a 1 M KOH solution. The aqueous phase was extracted three times with dichloromethane and the combined organic layers were dried over MgSO4. After removing the solvent by rotary evaporation, the crude material was purified by column chromatography, providing the pure product.

[0360] EXAMPLE 11: Synthesis of the intermediate 4CN-Hiqbdt by condensation reaction without catalyst

[0361] The synthesis method of the substituted intermediate 2-(benzo[l,2-b:4,5- b'] di thiophene) isoquinoline (Hiqbdt-der), i.e., the derivative 4CN-Hiqbdt, by crosscoupling reaction without catalyst is shown below, which can be summarized according to the following reaction diagram:

[0362] 4CN-Hiqbdt bdt-bor (0.9 mmol), prepared for example according to the method shown in EXAMPLE 1, was added to a solution of 4CN-iQ-NO (0.3 mmol), prepared for example according to the method shown in EXAMPLE 10, in DMSO (0.5 mL), and the reaction was stirred at 110°C for 16 hours. Subsequently, the reaction was cooled to room temperature and diluted with dichloromethane. Column chromatography of the reaction mixture provided the pure product (eluent: petroleum ether:EtOAc), usable as substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolinate binder (iqbdt- der) for subsequent preparation reactions of the complex according to the present invention.

[0363] The product was characterized by electrospray mass spectrometry (MS-ESI) and 'H NMR, the results of which are shown below. In this regard, it should be noted that the

[0364] NMR spectrum, the3H NMR spectrum expansion, the COSY-NMR spectrum, the13C NMR spectrum, and the13C NMR spectrum expansion, for the intermediate 4CN-Hiqbdt, are shown in Figures 19, 20, 21, 22 and 23, respectively.

[0365] MS-ESI: m / z: 343.0 [M+H]+; 384.0 [M+H+CH3CN]+.

[0366] 'H-NMR (CD2CI2, 300 MHz, 5 ppm): 8.94 (s, 1H), 8.80 (d, 1H), 8.46 (s, 1H), 8.40 (s, 1H), 8.28 (s, 1H), 8.07 (s, 1H), 7.99 (t, 1H), 7.87 (t, 1H), 7.60 (s, 1H), 7.44 (s, 1H).

[0367] EXAMPLE 12: Synthesis of the intermediate 4CN-Hiqbdt by Suzuki condensation reaction20

[0368] 4C -Hiqb(jt l-Cl-4-CN-iQ (0.6 mmol) and bdt-Bor (0.57 mmol) were dissolved in THF (6 mL) and the solution was bubbled with N2. Sodium carbonate (2.845 mmol) was dissolved in water (6 mL), the solution was bubbled with N2 and mixed with the organic solution. Pd(PPh3)4 (0.0284 mmol) was added to the mixture, and the temperature was brought to 65°C. The reaction was stirred at 65°C under nitrogen for 12 hours. Subsequently the reaction was left to reach room temperature, the organic phase was washed with a saturated NaCl solution. The aqueous phase was extracted 3 times with dichloromethane and the combined organic phases were dehydrated over MgSCL. After removing the solvent, the crude material was purified with column chromatography (eluent: Hexane(7)-Dichloromethane(2)-AcOEt(l)) providing the pure product in a 56% yield (0.318 mmol).

[0369] The product was characterized by electrospray mass spectrometry (MS-ESI), the results of which are shown below.

[0370] MS-ESI: m / z: 343.0 [M+H]+; 384.0 [M+H+CH3CN]+

[0371] The spectroscopic properties of the intermediate 4CN-Hiqbdt, summarized below in Table 3, were derived from the absorption, excitation and emission spectra shown in the graph of Figure 24.

[0372] Table 3: photo-physical properties of 4CN-Hiqbdt in CH2CI2 (CM 2 10~5Lmol~1) solutions at 298 K, and at 77K in 2 Me-THF.

[0373] EXAMPLE 13: Preparation of the OLED (NIR-OLED) comprising an active layer, incorporating the complex [Ir(iqbdt)2(dpm)J

[0374] The NIR-OLED was produced by a deposition in solution (spin coating) method, incorporating the emitter complex NIR, [Ir(iqbdt)2dpm], into an active layer based on conjugate compounds and polymers. The polymer carries out the role of "host matrix" to obtain a homogeneous dispersion of the complex of Ir(III), thus avoiding quenching mechanisms due to aggregation. Furthermore, the polymer was suitably selected with optimal electro-optical properties to obtain a full-NIR emission centered on the Ir(III). NIR-OLED Architecture: ITO / PEDOT:PSS (50 nm) / PVK(65%):OXD7(30%):[Ir(iqbdt)2dpm] (5wt. %)(~200 nm) / Ba(4 nm) / Al(100 nm) (ITO= indium-tin oxide; PEDOT:PSS=poly(3,4-ethylenedioxythiophene) polystyrene sulphonate; 0XD7 =l,3-bis(5- (4-tert-butylphenyl)-l,3,4-oxadiazol-2- yljbenzene; PVK=polyvinylcarbazole). The 0XD7 molecule is an additive for a better balance of the charge carriers within the active layer, useful for the correct operation of the device. The active layer was deposited by spin-coating 75 pL of 20 mg / ml toluene solution at 2000 rpm.

[0375] With a device architecture consisting of a single active layer, good performance was obtained already when the material was dispersed in a suitable polymeric matrix. The corresponding NIR-OLED exhibited an external quantum efficiency (emitted photons / injected charges ratio) of 0.46% and an electroluminescence in the entire NIR range 700-900 nm, with a peak at 758 nm (Figure 17a). Furthermore, the NIR-OLED turned on at 6 V and showed a stable electroluminescence for over 90 minutes when powered at 10 mA / cm2.

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Claims

CLAIMS:

1. Phosphorescent metal complex comprising at least one substituted benzofl, 2-b:4, 5- b']dithiophenyl-isoquinolate binder (iqbdt-der), having a structure of formula (I):whereinM is a metal selected from Ir(III) and Pt(II), m is an integer comprised between 1 and 2,L is a bidentate binder and n is an integer comprised between 1 and 2, the sum of n and m is equal to 2 or 3,R1is a substituent selected from the group consisting of -H; -F; -CF3; -CN; -CeFs - COOR2and -CONR3R4, andR2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls preferably selected from phenyl, 2- methylbenzene, 2,4-dimethylbenzene, 2,4,6-trimethylbenzene, k is the charge of the complex and is equal to 0 or +1, andX is an anion, preferably selected from Cl", BFF, or PFe', wherein j is the coefficient of the anion X and is equal to 0 or 1.

2. Complex according to claim 1, wherein L is selected from 1-phenylpyrazole (ppz), substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinoline (Hiqbdt-der) having a structure of formula (I5), substituted P-diketone having a structure of formula (Iis), preferably 2,2,6,6-tetramethyl-3,5-heptanedione (dpm) or 2,4-pentanedione (acac),substituted picolinic acid having a structure of formula (I19), substituted bipyridine having a structure of formula (I20), substituted phenanthroline having a structure of formula (I21), or substituted 2-triazolylpyridine having a structure of formula (I22).

3. Complex according to claim 1 or 2, characterized by an absolute value of energy difference between the frontier molecular orbitals (H0M0-LUM0) less than 2.40 eV.

4. Complex according to any one of claims from 1 to 3, characterized by a near-infrared emission wavelength (2em), measured at 298 K, comprised between 700 nm and 900 nm, preferably between 713 and 790 nm, preferably between 728 and 770 nm, preferably equal to 750 nm.

5. Complex according to any one of claims from 1 to 4, characterized by a quantum luminescence efficiency ( L), measured at 298 K, comprised between 0.1 and 15%.

6. Complex according to any one of claims from 1 to 5, characterized by a 'H NMR spectrum, recorded in a solvent selected from CD2CI2 and CDCh, at an operating frequency equal to 300 MHz, comprising at least one singlet, preferably two singlets, for each substituted benzofl, 2-b:4,5-b']dithiophenyl-isoquinolate (iqbdt-der) binder, said at least one singlet being identified by a relative chemical shift comprised between 6.50 and 9.79 ppm.

7. Synthetic intermediate for the preparation of the metal complex according to any one of claims from 1 to 6, characterized by a structure of formula (I5), or by a structure of formula (le) or by a structure of formula (I7):whereinR1is a substituent selected from the group consisting of -H; -F; -CF3; -CN; - CeFs - COOR2and -CONR3R4, andR2, R3and R4are independently selected from hydrogen, linear or branched alkyls having from 1 to 4 carbon atoms or aryls selected from phenyl, 2-methylbenzene, 2,4- dimethylbenzene, 2,4,6-trimethylbenzene.

8. Method for preparing the metal complex of Ir(III) according to any one of claims from 1 to 6, comprising the steps:A. preparing an Ir(III) dimer having two chloride-compounds selected from the group consisting of: the intermediate product of formula (F) according to claim 7, a compound having a structure of formula (Is):B. preparing the bidentate binder L, said binder L preferably being chosen from- 2,2,6,6-tetramethyl-3,5-heptanedione (dpm) in the case in which the dimer is the intermediate of formula (F) or the compound of formula (Is), or- the intermediate of formula (Is) in the case in which the dimer is the compound of formula (Is);C. carrying out a binder substitution reaction, reacting the dimer of Ir(III) having two bridging-chlorides with the bidentate binder L, to obtain the metal complex of Ir(III) according to formula (I);D. optionally, isolating the metal complex thus obtained.

9. Method for preparing the metal complex of Pt(II) according to any one of claims from 1 to 6, comprising the steps:E. preparing the intermediate product of formula (I7), according to claim 7;F. preparing the bidentate binder L;G. carrying out a binder substitution reaction, reacting the intermediate product having a structure of formula (I7) with the bidentate binder L, to obtain the metal complex of Pt(II) according to formula (I);H. optionally, isolating the metal complex thus obtained.

10. Method for preparing according to claim 7 or 8, wherein the binder substitution reaction is carried out at a temperature of 100°C or more, using as a solvent- glycerol, or- 2-ethoxy ethanol as solvent, in the presence of potassium or sodium carbonate.

11. Use of the metal complex according to any one of claims from 1 to 6 in lightemitting solid-state optoelectronic devices, preferably selected from organic lightemitting diodes (OLEDs), organic light-emitting transistors (OLETs) or electrochemical light-emitting cells (LECs or LEECs).

12. Light-emitting solid-state optoelectronic device, comprising: at least two electrodes; and an active layer, comprising the metal complex according to any one of claims from 1 to 6.

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