EP2917947A1

EP2917947A1 - Novel method for manufacturing organic electronic devices

Info

Publication number: EP2917947A1
Application number: EP13792767.9A
Authority: EP
Inventors: Denis Fichou; Ludovic Tortech; Moslem ALAAEDDINE
Original assignee: Centre National de la Recherche Scientifique CNRS
Current assignee: Centre National de la Recherche Scientifique CNRS
Priority date: 2012-11-08
Filing date: 2013-11-08
Publication date: 2015-09-16
Also published as: FR2997793A1; JP2016503581A; CN104769734A; FR2997793B1; US20150280125A1; WO2014072944A1; US9793480B2

Abstract

The present invention relates to a method for manufacturing organic electronic devices including a dipyrannylidene film as an anodic interface layer, said method being carried out in a vacuum and without any exposure to air. The invention also relates to organic devices resulting from said method, more specifically to organic solar cells (OSC).

Description

NEW PROCESS FOR MANUFACTURING ORGANIC ELECTRONIC DEVICES

The present invention relates to a method for manufacturing organic electronic devices comprising a film based on dipyranylidenes of formula (I) as anodic interfacial layer, and to the organic devices obtained according to this process, and more particularly to organic solar cells (OSC). manufactured according to this process.

Current electronic systems such as OSCs require complex technologies that make the optimization of their optical and electronic performance difficult.

One of the main optimization methods consists in using at the anode of the photovoltaic system a conducting polymer such as poly (3,4-ethylenedioxythiophene) -poly (styrenesulphonate) (PEDOT: PSS), the latter being inserted between an electrode of tin-doped indium oxide (ITO) and a photosensitive active layer (Crispin et al., Journal of Polymer Science: Part B: Polymer Physics, Vol 41, 2561-2583 (2003)). The substrates coated with PEDOT: PSS are optically anisotropic and have little visible absorption; the conductivity of PEDOT: PSS-coated substrates prepared using commercial solutions is generally between 1 and 50 cm ^-1 .

PEDOT: PSS-based devices are still the subject of many works (Groenendaal et al., Adv., Mater., 2000, 12, No. 7) relating to:

the improvement of the photosensitive active layer by the use of new absorbent materials, by structuring the charge network, or by improving the transport of charges, and

- the improvement of the interfaces thanks to a better quality of the contacts or a collection of the loads.

Thus, the anodic interfacial layers used in electronic devices must have:

good electronic properties, and more particularly a high conductivity, as well as an adapted output work making it possible to optimize the energy barrier at the interface between the ITO electrode and the photosensitive active layer, facilitating the collection of positive charges,

good optical properties characterized by minimal absorption, and

good stability and ease of shaping allowing the formation of homogeneous and continuous films. Output work means the minimum energy, measured in electron volts (eV), needed to pull an electron from the Fermi level of a metal to a point at infinity outside the metal. The photoelectric effect consists of a release of an electron when a photon with energy higher than the output work arrives on the metal. The difference between the incident photon energy and the output work is provided to the electron as kinetic energy. Thus, the photoelectric output work is calculated according to the formula:

q> = hf ₀

where h is the constant of Pîanck and f ₀ is the minimum frequency of the photon from which the photoelectric emission occurs.

The output work of the electrodes plays a crucial role in the field of plastic electronics because it influences the distribution of the internal electric field and the height of the energy barrier between the electrode and the photosensitive active layer of the device. . This barrier greatly influences the injection of charge carriers, especially in the case of organic light-emitting diodes (OLEDs), or on the contrary, dominates the collection of charges from the active layer to the electrode, as for example in the case of CSOs . In order to facilitate the transport of holes, materials having high output work are preferred as the anode.

At present, the most commonly used devices are devices based on PEDOT: PSS. However, when it is used as interfacial layer on ITO electrodes, the PEDOT: PSS must be applied in the form of a thin film having a thickness of less than one hundred nanometers, in order to guarantee a high optical transmission; In this case, the PEDOT film: PSS has a low conductivity. Surface defects and holes may also appear on the surface of the PEDOT: PSS film when the applied polymer layers are too thin. On the other hand, when it is applied in a thicker layer (between 150 and 200 nm thick), z ^' .e. to achieve higher conductivities allowing lateral transport of the photocurrent, there is then a loss in the optical transmission coefficient.

PEDOT: PSS-based systems also have other disadvantages:

the interface between the films of PEDOT: PSS and the ITO-based electrodes is unstable, the indium atoms diffusing into the polymer layer and impairing its performance, the electrical contact between the films of PEDOT: PSS and the ITO-based electrodes is weak, the polymer layer does not reach many electronically active sites on the surface of the ITO electrode, which increases series resistances and greatly reduces the collection of holes at the electrode,

the conductivity and the roughness of the PEDOT: PSS layers are dependent on the conditions of application, and in particular on the moisture content and the annealing temperatures.

Alternative routes to the use of conductive polymers at the anode interface have also been envisaged, for example:

the use of monolayers (Campbell et al., Appl.

(24), 3528-3530; Kim et al, Appl. Phys. Lett, 92, 133307 (2008); Akkerman et al, Small 2008, 4, No, 1, 100-104; Armstrong et al. Thin Solid Films, 445, 2003, 342-352), the latter being generally covalently bonded chemically or electrochemically to the surface of the ITO electrode. However, these monolayers are not very thick (a few tens of angstroms) and lead to uneven coverage of the substrates they functionalize, leaving roughness and thus leading to poor quality interfaces,

the use of charge-transfer complexes (Hanson et al, J. Am Chem Chem, Vol 127, No. 28, 2005, 127, 10058-10062, Kahn et al, Appl Phys Lett, Vol. 79, No. 24, 4040-4042), the latter nevertheless having the disadvantage of having energy levels that are difficult to adjust.

The inventors have demonstrated in Application WO 201 1/045478 the properties of substrates coated with dipyrarmylidene films used as anodic interfacial layer in electronic devices.

They have now discovered that a process for manufacturing organic electronic devices using such dipyrranylidene compounds, carried out under vacuum and in the absence of any exposure to air, significantly improves the performance of organic devices. from such a process.

Such a method avoids any progressive degradation of the manufactured organic electronic devices, and considerably improves their photocurrent densities and their conversion efficiencies. Conversion efficiencies greater than 3% and up to 6% have been obtained for photovoltaic cells manufactured according to the method of the invention, these results being to be compared with the maximum values of 1.5% obtained for the devices. described in Application WO 2011/045478. The first object of the present invention therefore relates to a method of manufacturing an organic electronic device implemented in the absence of any exposure to air, and comprising at least the following steps:

(i) depositing, by vacuum evaporation, preferably in an ultrahigh vacuum chamber, onto a substrate, a film comprising at least one compound of formula (I) below:

(I)

in which :

Xa and Xb, which are identical or different, are chosen from N, P, O, S, Se or Te, Ri, R ₂ , R ₃ and R 4, which may be identical or different, represent a group chosen from aryl or heteroaryl rings; having 4 to 10 carbon atoms, said aryl or heteroaryl rings being optionally substituted by one or more halogen atoms, -OH, -CN, -NO ₂ , alkyl groups having 1 to 30 carbon atoms, alkoxy -OCN or ester -C (O) OC _n H2 _{n +} 1, wherein 0≤ n 16,

(ii) the deposition under an inert atmosphere of a photosensitive active layer,

(iii) optionally, the annealing under an inert atmosphere of the photosensitive active layer deposited during step (ii),

(iv) the deposition under an inert atmosphere of an exciton active dissociation layer, said layer preferably being based on lithium fluoride (LiF),

(v) deposition under an inert atmosphere of a layer serving as a cathode electrode.

All the steps of the process are carried out under vacuum or inert atmosphere, so that the organic electronic device is never exposed to air during its manufacture. When the steps are carried out under an inert atmosphere, they are preferably carried out under an inert atmosphere of nitrogen or argon.

In addition, the inventors have found that the film comprising a compound of formula (I) in combination with a conductive intermediate layer can also act alone as a conductive electrode, without it being necessary to apply it on a substratum driver such as ΓΙΤΟ. This improvement makes it possible in particular to manufacture ITO-free devices (ITO-free devices).

For the purposes of the present invention, the following terms mean:

Alkoxy: an O-alkyl group in which the alkyl group is a saturated, linear or branched, saturated hydrocarbon aliphatic group;

- Halogen atom: an atom of bromine, chlorine, iodine or fluorine; the bromine, chlorine and fluoro designations being preferred;

Aryl group: denotes any functional group or substituent derived from at least one aromatic ring; an aromatic ring corresponds to any planar mono- or polycyclic group comprising a delocalized π system in which each atom of the cycle comprises an orbital p, said orbital p overlapping each other;

Heteroaryl group: denotes any functional group or substituent derived from at least one aromatic ring as defined above and containing at least one heteroatom chosen from N, P, O and S.

The compound of formula (I) of the invention is preferably present in the film in the form of particles having an average diameter less than or equal to 300 nm, preferably less than or equal to 250 nm, and even more preferably less than or equal to 200 nm.

According to an advantageous embodiment, the atoms Xa and Xb of the compound of formula (I) are identical and chosen from O, S or Se, and preferably Xa = Xb = 0.

The aryl or heteroaryl rings R 1, R 2, R ₃ and R 6 of the compound of formula (I) are preferably chosen from phenyl, naphthyl, anthracyl, benzoxazolyl, thiophenyl or alkoxy-thiophenyl, furyl, pyrrolyl and pyridyl rings. pyrazyl, pyrazolyl, pyridazyl, pyrimidyl, triazyl, imidazolyl, oxazolyl, indyl, indazolyl, quinolyl and quinoxalyl, and more preferably R 1, R _2; R and R4 are the same and represent phenyl.

In addition to the compound of formula (I), the film of step (i) may also comprise other constituents, and more particularly electron acceptor molecules leading to the formation of charge transfer complexes, such as the 7,7,8,8-tetracyana-p-quinodimethane (TCNQ) or tetrafluoro-7,7,8,8-tetracyana-β-quinodimethane (F ₄ TCNQ). These electron acceptor molecules are introduced in a small amount relative to the compound of formula (I). Preferably, the ratio by electron acceptor molecule / compounds of formula (I) is between 1/99 and 5/95. And they act as doping agents by increasing the intrinsic conduction properties of the holes of the compound of formula (I),

According to an advantageous embodiment, the film comprising at least one compound of formula (I) deposited during step (i) has a thickness less than 45 nm, preferably less than or equal to 30 nm, and even more preferably lower or equal to 15 nm.

The deposition by vacuum evaporation of step (i) makes it possible to sublimate the compound of formula (I). It can be carried out by chemical vapor deposition CVD, this technique consisting in adding a metal precursor to a source of liquid carbon (such as toluene, benzene or cyclohexane), the solution then being converted into fine droplets, transported by an inert gas to an oven. In practice, the compound of formula (I) is placed in the form of powder in a crucible, then covered with alumina, and then heated under vacuum until the compound of formula (I) passes from the state solid in the liquid state (sublimation). The vapor stream of the compound of formula (I) is then oriented towards the substrate so as to cover it with a film consisting of the compound of formula (I). Step (i) is carried out at an evaporation rate of less than 1 Å / s, preferably less than or equal to 0.4 Å / s, and even more preferably less than or equal to 0.1 Å / s.

The substrate of step (i) may be an insulating or conductive substrate. This substrate can be rigid or flexible. In the case of an insulating substrate, it is preferably chosen from glass or polymers such as polyethylene terephthalate (PET), amorphous polyethylene (amorphous PE) and amorphous polystyrene (amorphous PS). In the case of a conductive substrate, it is preferably chosen from metal oxides such as aluminum oxide, indium oxide, tin oxide, iridium oxide, silicon oxide, iron oxide and copper oxide, and even more preferably tin-doped indium oxide (ITO). When the substrate is a conductive substrate it may have been previously deposited on a base support, preferably glass or polymer-based, said deposit being made in an ultrahigh vacuum chamber.

Advantageously, the distance between the source of the compound of formula (I) and the substrate during step (i) is between 10 and 40 cm, and preferably between 25 and 35 cm.

The method of the invention may comprise between steps (i) and (ii) the deposition of a conductive intermediate layer, said layer being preferably a layer of PEDOT: PSS. This step is performed in a glove box under inert atmosphere. Of Preferably, the deposition of the conductive intermediate layer is performed by spin coating ("spin coating").

According to an advantageous embodiment, the deposition of a photosensitive active layer during step (ii) is carried out in a glove box placed under an inert atmosphere of nitrogen or argon. Said deposit is preferably made by spin coating (or "spin-coating").

Preferably, the photosensitive active layer of step (ii) is a layer consisting of at least two highly absorbing materials in the visible, one being electron donor and the other electron acceptor, this layer undergoing a high-speed charge transfer and creating positive charges (holes) and negative charges (electrons) under the effect of a light irradiation. This photosensitive active layer may be the combination of phthalocyanine derivatives, pentacene, thiophene, triphenylamine, p-type polymers, with molecules such as fullerene derivatives or perylenes, the mixture P ₃ HT: PCBM being the preferred association.

The active photosensitive layer deposited during step (ii) may also be coated with an exciton active dissociation layer (or EBL for Exciton Blocking Layer), which may be based on lithium fluoride (LiF) in OSC devices. or alumina based in OLED or PLED devices. Advantageously, the exciton active dissociation layer has a thickness of less than 10 Å, preferably less than 8 Å, and even more preferably of between 5 and 7 Å.

The optional annealing step (iii) under an inert atmosphere is advantageously carried out in a tubular furnace, at a temperature of between 30 and 150 ° C., preferably between 80 and 150 ° C., and even more preferably close to 120 ° C. C, for a period of between 1 minute and 24 hours, preferably between 5 to 20 minutes, and even more preferably for approximately 10 minutes.

The step (iv) of deposition under an inert atmosphere of an exciton active dissociation layer may be a dry deposition carried out under an inert atmosphere, for example by chemical vapor deposition CVD, this deposition being preferably carried out at a temperature of 30.degree. evaporation rate less than 1 Å / s, more preferably less than or equal to 0.4 Å / s, and even more preferably less than or equal to 0.1 Å / s. The dry deposition of step (iv) can be carried out at an annealing temperature of between 80 and 120 ° C and a pressure of between 10 ^' and 10 ^' mbar for a period of between 2 and 4 hours. According to a preferred embodiment, the deposition of step (v) is carried out in an ultrahigh vacuum chamber. This step (v) can be carried out dry at an evaporation rate of less than or equal to 3 Å / s, and preferably of between 0.1 and 2 Å / s,

Advantageously, the layer of step (v) serving as a cathode electrode is based on aluminum, gold, calcium, copper, samarium, platinum, palladium, chromium, cobalt or aluminum. iridium.

According to a particularly preferred embodiment, in the device manufactured according to the method of the invention the substrate is made of glass, plastic or ITO-based, and the photosensitive active layer is based on P ₃ HT: PCBM.

Another subject of the invention relates to an organic electronic device obtained according to the process of the invention, said device being chosen from organic light-emitting diodes (OLEDs), polymeric light-emitting diodes (PLEDs), organic field-effect transistors ( OFET) and organic solar cells (OSC).

The invention particularly relates to an organic solar cell

(OSC) obtained according to the process of the invention, wherein the substrate is based on polymer or oxide, and in the latter case preferably based on ITO.

The compounds of formula (I) can be synthesized according to methods known to those skilled in the art, such as those described by Sandman et al., J. Chem. Soc. Chem. Commun., 1977, 687, 177-178, and Otsubo et al, J. Chem. Soc. Perkin Trans., 1993,

1815-1824.

In addition to the foregoing, the invention also comprises other arrangements which will emerge from the description which follows, which refers to examples of implementation of the method of the invention and to the evaluation of OSC devices manufactured according to this process, as well as to the accompanying drawings in which:

1 represents the current-voltage curves of an OSC device according to the invention (light curve: in the dark, dark curve: under illumination AM1.5G (75 mW.cm ^-2 )),

FIG. 2 represents the EQE spectrum of the device of the invention (curve having a maximum of 80% for a wavelength of approximately 530 nm) and the absorption spectrum of the ITO / DIPO- ₄ / PEDOT device: PSS / P ₃ HT: PCBM, and

Figure 3 shows AFM microscopy images (2D and 3D) of the anode layer of an OSC device according to the invention. EXPERIMENTAL PART :

A film-coated substrate comprising bis-4,4 '- (2,6-diphenyl-pyranylidene) (ϋϊΡΟ-Φ) as a compound of formula (I) was prepared according to the procedure described hereinafter .

The formula for ϋΙΡΟ-Φ ₄ is as follows:

A- Synthesis of ΡΙΡΟ-Φ ₄

Step 1: Synthesis of 1,5-diphenyl-1,5-pentadione

In a 100 ml two-neck flask, a solution of glutaryl chloride (10 mmol, 1.3 ml) solubilized in anhydrous dichloromethane (20 ml) is introduced under an inert atmosphere. The aluminum chloride (30 mmol, 4.00 g) is added to the mixture, which immediately turns yellow-orange. A solution of benzene (20 mmol, 1.8 mL) solubilized in anhydrous dichloromethane (10 mL) is added dropwise at room temperature. The solution becomes intense red. The mixture is then refluxed for 24 hours and is colored brown-black. The mixture is then brought back to ambient temperature and then poured into a crystallizer containing 20 ml of 10% acidified water, with stirring. A black solid is formed and then filtered on Buchner. The yellow organic phase is then extracted with ethyl acetate, dried over MgSO ₄ , filtered, concentrated on a rotary evaporator and recrystallized from 20 ml of methanol. The product obtained is a white solid with a mass of 680 mg. The yield of the reaction is 27%.

TLC (eluent: petroleum ether / ethyl acetate 1: 1): 0.75

1 H NMR (CDCl3, 400 MHz): δ = 7.98 (d, 4H, ³ J = 7.1 Hz), 7.57 (t, 2H, ³ J = 7.3 Hz), 7.47 (t, 4H) , ³ J = 7.3 Hz), 3.13 (t, 4H, ³ J = 6.9 Hz), 2.21 (quint, 2H, ³ J - 6.9 Hz)

Step 2: Synthesis of diphenyl-2,6-pyrylium perchlorate In a 100 mL two-necked flask, the 1,5-diphenyl-1,5-pentadione prepared in step 1 (10 mmol, 2.52 g) is mixed with phosphorus pentasulfide (15 mmol, 3.34 g), acetic acid (60 ml) and FeCl ₃ (60 mmol, 6.40 g) and then refluxed for 3 hours. The solution then becomes orange and a white precipitate is formed. The precipitate is removed by sinter filtration and then washed with hot acetic acid. The solution is concentrated on a rotary evaporator and recrystallized by addition of ether (500 ml). The precipitate obtained is filtered on sintered and then dried on a rotary evaporator. The product obtained is a solid red mass of 850 mg. The yield of the reaction is 24%.

1H NMR (CD ₃ CN, 400 MHz) δ = 8.90 (t, 1H), 8.52 (d, 2H), 8.18 (d, 4H), 7.60 (t, 4H), 7.50 (t, 2H).

Step 3: Synthesis of bis-4,4 '- (2,6-diphenyl-pyrannylidene) (DIPO- ₄ )

In a 250 ml two-neck flask, the diphenyl-2,6-pyrylium perchlorate solution (10 mmol, 3.50 g) is solubilized in 200 ml of distilled acetonitrile and the mixture is refluxed for 2 hours under inert atmosphere. Zinc powder (30 mmol, 1.96 g) is added in small portions, and the mixture is refluxed for 24 hours. The solution is filtered, rinsed with toluene and evaporated on a rotary evaporator. A black oil is obtained which is recrystallized from hexane / ethanol 1: 1. After purification by TLC (eluent: petroleum ether / ethyl acetate 8: 2), a black solid of mass 650 mg is obtained. The yield of the reaction is 13%.

IR (cm ^"): 2920, 1650, 1605, 1550, 1488, 1441, 1229, 1071, 750, 685.

B-Manufacture of an Organic Solar Cell (OSC) According to the Process of the Invention

The preparation of the OSC devices of the invention takes place in several:

A l ^st step that aims to prepare an ITO substrate of 10 mm wide and 25 mm long, to avoid short-circuit phenomenon. An ITO electrode on a glass support is dipped with a solution of FeCl ₃ + HCl heated at 50 ° C for 2 minutes, rinsed successively in different solvent baths: ethyl acetate, Decon (5% aqueous solution) , ethanol and acetone, then stripped in a UV-ozone chamber by forced oxidation.

A 2 ^nd step of depositing bis-4,4 '- (diphenyl-2,6-pyrannylidène) (ϋιΡΟ-Φ ₄₎ on a glass substrate / ITO by evaporation under vacuum (pressure = 10 ^"7 mbar; deposition rate = 0.1 Å / s, to form a 10 nm thick layer The distance between the crucible (molybdenum crucible covered with alumina) containing DIPO-O ₄ and the glass / ITO substrate is 35 cm. crucible heated by Joule effect (0.5 V, 50 A, 25 W.) The thickness of the layer is monitored using a calibrated quartz scale for tris-hydroxy-8 aluminum quinolinate (Alq3 ) (frequency of vibration = 6.01 MHz, ± 1%) The molecule Aq3 is used as reference standard for the deposition of all organic molecules. The frequency of the quartz crystal of 6.01 MHz is the nominal working frequency.

A ^3rd stage in which the glass substrate / ITO / DIPO- <i> 4 is returned to atmospheric pressure under an inert nitrogen atmosphere and transferred to a glove box via an air lock. A conductive intermediate layer of PEDOT: PSS (concentrated suspension at a level of 0.29% by weight in the aqueous phase, Sigma-Aldrich) is deposited by spin coating (spin coating) at a speed of 2000 rpm for 50 seconds. .

A ^4th stage at which the glass substrate / ITO / DIPO- Φ PEDOT: PSS is covered with a deposition of a photosensitive active layer P ₃ HT: PCBM the following concentrations: 15 mg P ₃ HT and 12 mg of PCBM (in 1 mL of chlorobenzene), at 1000 rpm for 20 seconds, 1200 rpm for 20 seconds and finally 2000 rpm for 10 seconds. The thicknesses obtained by this method are of the order of 120 ± 10 nm.

A ^fifth step during which the glass / ITO / DIPO-PIEDOT: PSS / P ₃ HT: PCBM device is then transferred to a UHV (Ultra High Vacuum) chamber where a lithium fluoride LiF (Sigma) deposit is successively made. - Aldrich) by thermal evaporation under a stable evaporation regime of 0.01 Å / s, until a layer with a thickness of 0.5 nm is obtained, then an aluminum deposit by thermal evaporation under a regime stable evaporation rate of 0.4 Å / s and a pressure of 10 ^" mbar until an aluminum layer thickness of 80 nm.

A 6 ^th step in which the device glass / ITO / DIPO- 0> ₄ / PEDOT: PSS / P ₃ HT: PCBM / LiF / Al is then transferred into a glove box placed at atmospheric pressure and under an inert atmosphere nitrogen through an airlock.

Finally, a deposit of silver lacquer (area ~ 1 x 1 mm ² ) is made using a thin object (needle tip) on the aluminum layer to allow a good electrical contact of the aluminum electrode. Once deposited, the lacquer is dried at room temperature for 45 minutes.

C- Characterization of the OSC Device of the Invention

The current-voltage characteristics of the devices in the dark and under illumination are measured under an inert nitrogen atmosphere using a Keithley 2406 current meter and a micro-tip station.

The characteristics in the dark are determined by placing a black veil on the devices to avoid the influence of diffuse light. The current-voltage characteristics of devices under illumination are measured on an optical bench equipped with:

1) a xenon lamp (Oriel, 150 W) simulating the solar spectrum and delivering a power of 75 or 100 mW.cm ^'2 at the OSC devices,

2) a monochromator (Cornerstone CS 120),

3) an IR filter placed between the lamp and the OSC devices to prevent them from overheating,

4) synchronous detection (HDTS brand), and

5) an optical pulsator ("chopper" brand Lot Oriel).

The solar simulator is calibrated so as to restore the solar nominal power as the international conventions have fixed for this type of device (75 or 100 mW / cra ² ). The measurements can be performed under white light or under mono-chromatic light. Under white light the component is contacted using the micro-peak station and is illuminated using the solar simulator. The electrical measuring apparatus (Keithley 2406) records in zero or variable field the current extracted from the OSC device of the invention. This measurement makes it possible to determine the external conversion efficiency PCE of the device (PCE for Power Conversion Efficiency).

The current-voltage characteristics in the dark and under illumination by a white light make it possible to evaluate the performances and the behavior of the OSC devices of the invention. We can thus define the following parameters:

the short-circuit current Isc obtained for a zero voltage, this current being proportional to incident illumination (Jsc = Isc / S, where S is the area of the device),

the open circuit voltage Voc measured for a zero current,

Imax and Vmax are the I-V coordinates (Pmax - Imax x Vmax), - the Form Factor (FF) equal to: FF = (Vmax x Imax) / (Voc x Isc)

The current-voltage curves obtained for the OSC device of the invention are shown in FIG. 1 and the main corresponding photovoltaic characteristics are collated in the following Table I:

Table I:

It is found that the OSC device of the invention has better performances than those obtained with the devices described in Application WO 2011/045478, and in particular:

the open circuit voltages Voc are higher,

the short-circuit currents Isc and the photocurrent densities Jsc are higher.

As a result, the external conversion efficiency (PCE - 6.0% instead of 1.5%) is much higher than that of the devices described in Application WO 2011/045478.

Under monochromatic illumination the light of the lamp passes through a monochromator (Comerstone CS120) and a chopper to restore a monochromatic pulse light. The electrical measurement is then performed using synchronous detection. This type of measurement makes it possible to characterize the spectrum of action and the external quantum efficiency (EQE for "Exte nal Quantum Efficiency") of the photo-voltaic device. Figure 2 shows the EQE characteristics of the OSC device of the invention. It is found that the EQE spectrum follows the absorption spectrum of the active material P ₃ HT: PCBM with a very high maximum at 80% for a wavelength of about 530 nm.

Finally, FIG. 3 shows AFM microscopy images (2D and 3D) which reveal a needle nanostructuration of the anode layer of the OSC device of the invention.

Claims

1) Process for manufacturing an organic electronic device comprising at least the following steps:

(i) the deposition by vacuum evaporation on a substrate of a film comprising at least one compound of formula (I) below:

(I)

in which :

Xa and Xb, which are identical or different, are chosen from N, P, O, S, Se or Te, Ri, R ₂ , R ₃ and Pv 4, which may be identical or different, represent a group chosen from aryl or heteroaryl rings; having 4 to 10 carbon atoms, said aryl or heteroaryl rings being optionally substituted by one or more halogen atoms, -OH, -CN, -N <¾ groups, alkyls having 1 to 30 carbon atoms, alkoxy -OC _n H _{2ii + 1} or ester -C (O) OC _n H ₂ " ₊ i, wherein 0≤ n 16,

(ii) the deposition under an inert atmosphere of a photosensitive active layer,

2) Method according to claim 1, characterized in that it is implemented in

3) Process according to claim 1 or claim 2 wherein the atoms Xa and Xb of the compound of formula (I) are identical and selected from O, S or Se, and preferably Xa = Xb = O. 4) Process according to one of claims 1 to 3 wherein the aryl or heteroaryl rings R], R ₂ , R ₃ and R of the compound of formula (I) are selected from the rings phenyl, naphthyl, anthracyl, benzoxazolyl, thiophenyl or alkoxy-thiophenyl, furyl, pyrrolyl, pyridyl, pyrazyl, pyrazolyl, pyridazyl, pyrimidyl, triazyl, imidazolyl, oxazolyl, indyl, indazolyl, quinolyl and quinoxalyl, and preferably R 1, R ₂ , R ₃ and R 4 are identical and represent a phenyl.

5) Method according to one of claims 1 to 4 wherein the deposition by vacuum evaporation of step (i) is carried out in an ultrahigh vacuum chamber.

6) Method according to one of claims 1 to 5 wherein the deposition by vacuum evaporation of step (i) is carried out at an evaporation rate of less than 1 Ås, preferably less than or equal to 0.4 Ås and even more preferably less than or equal to 0.1 μs.

7) Method according to one of claims 1 to 6 wherein the film comprising at least one compound of formula (I) has a thickness less than 45 nm, preferably less than or equal to 30 nm, and even more preferably less than or equal to at 15 nm. 8) Method according to one of claims 1 to 7 wherein the substrate is selected from insulating substrates such as glass or polymers, or conductive substrates such as metal oxides.

9) Method according to one of claims 1 to 8 wherein the distance between the source of the compound of formula (I) and the substrate is between 10 and 40 cm, and preferably between 25 and 35 cm, when the step (i).

10) Method according to one of claims 1 to 9 wherein a step of depositing a conductive intermediate layer, said layer preferably being a layer of PEDOT: PSS, is performed between steps (i) and (ii).

11) Method according to one of claims 1 to 10 wherein the deposition of step (ii) is carried out in a glove box placed under an inert atmosphere of nitrogen or argon. 12) Method according to one of claims 1 to 11 wherein the deposition of the step

(ii) is made by spin (or spin-coating).

13) Method according to one of claims 1 to 12 wherein the annealing of the step

(iii) is carried out in a tubular oven, at a temperature between 30 and 150 ° C, for a period of between 1 minute and 24 hours.

14) Method according to one of claims 1 to 13 wherein the deposit of the step

(iv) is carried out dry, preferably by chemical vapor deposition CVD, at an evaporation rate of less than 1 Å / s, preferably less than or equal to 0.4 Å / s, and even more preferably lower or equal to 0.1 Å / s.

15) The method of claim 14 wherein the dry deposition is performed at an annealing temperature of between 80 and 120 ° C and a pressure between 10 and 10 ^'mbar for a period of between 2 and 4 hours.

16) Method according to one of claims 1 to 15 wherein the deposition of the step

(v) is made in an ultrahigh vacuum chamber.

17) Method according to one of claims 1 to 16 wherein the deposition of step (v) is carried out dry at an evaporation rate less than or equal to 3 Å / s, and preferably between 0, 1 and 2 Â / s.

18) Method according to one of claims 1 to 17 wherein the layer serving as a cathode electrode deposited in step (v) is based on aluminum, gold, calcium, copper, samarium, platinum, palladium, chromium, cobalt or iridium.

19) Method according to one of claims 1 to 18 wherein the substrate is made of glass, plastic or tin-doped indium oxide (ITO), and the photosensitive active layer is P-based ₃ HT: PCBM.

20) An organic electronic device obtained according to the method of claims 1 to 19, chosen from organic light-emitting diodes (OLEDs), diodes polymer electroluminescent (PLED), organic field effect transistors (OFET) and organic solar cells (OSC).

21) organic solar cell (OSC) obtained according to the method of claims 1 to 19.