BENZODITHIOPHENE CONJUGATED POLYMERS AND ORGANIC DEVICES CONTAINING THEM
20220145003 · 2022-05-12
Assignee
Inventors
Cpc classification
C08G61/126
CHEMISTRY; METALLURGY
C08G2261/3243
CHEMISTRY; METALLURGY
C08G2261/1426
CHEMISTRY; METALLURGY
H10K85/113
ELECTRICITY
C07D519/00
CHEMISTRY; METALLURGY
H10K30/30
ELECTRICITY
International classification
Abstract
There is a benzodithiophene conjugated polymer of general formula (1):
##STR00001##
There are also photovoltaic devices having the polymer. There are also organic devices having the polymer.
Claims
1. Benzodithiophene conjugated polymer of general formula (I): ##STR00040## wherein: R.sub.1 and R.sub.2, mutually identical or different, are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; cycloalkyl groups optionally substituted; aryl groups optionally substituted; heteroarylic groups optionally substituted; linear or branched, C.sub.1-C.sub.30 alkoxy groups; thiol groups —S—R.sub.3 wherein R.sub.3 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; polyethylenoxy groups R.sub.4—O—[CH.sub.2—CH.sub.2—O].sub.m—, wherein R.sub.4 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups, and n is an integer ranging from 1 to 4; —R.sub.5—OR.sub.6 groups, wherein R.sub.5 is selected from linear or branched, C.sub.1-C.sub.30 alkylene groups, and R.sub.6 represents a hydrogen atom or is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; —COR.sub.7 groups, wherein R.sub.7 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; —COOR.sub.8 groups, wherein R.sub.8 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; polyethylenoxy groups R.sub.9—[—OCH.sub.2—CH.sub.2—].sub.p—, wherein R.sub.9 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups, and p is an integer ranging from 1 to 4; R.sub.10-T groups, wherein R.sub.10 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups and T represents a polyalcohol group —OCH.sub.2—CHOH—CH.sub.2OH, an amino group —N(CH.sub.3).sub.2, a carboxylic group —CO.sub.2H, a —CHO group, or a cyano group (—CN); wherein Ar represents an electron-acceptor group or an electron-donor group; wherein n is an integer ranging from 10 to 500.
2. Benzodithiophene conjugated polymer of general formula (I) according to claim 1, wherein in said general formula (I), Ar is selected from the group consisting of ##STR00041## ##STR00042## wherein: B represents a sulfur atom, an oxygen atom, a selenium atom, or represents a N—R.sub.14 group, wherein R.sub.14 represents a hydrogen atom or is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; B′ represents a carbon atom, a silicon atom, or a germanium atom; Q represents a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, or C—R.sub.14 group, wherein R.sub.14 has the same meanings given above; Ru, mutually identical or different, are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; cycloalkyl groups optionally substituted; aryl groups optionally substituted; heteroarylic groups optionally substituted; linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkoxy groups; polyethylenoxy groups R.sub.15—[—OCH.sub.2—CH.sub.2—].sub.q—, wherein R.sub.15 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups, and q is an integer ranging from 1 to 4; —R.sub.16—OR.sub.17 groups, wherein R.sub.16 is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkylene groups, and R.sub.17 represents a hydrogen atom or is selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; —COR.sub.17 groups, wherein R.sub.17 has the same meanings given above; —COOR.sub.17 groups, wherein R.sub.17 has the same meanings given above; or they represent a group —CHO or a cyano group (—CN); R.sub.12 and R.sub.13, mutually identical or different, represent a hydrogen atom, a fluorine atom, or are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; cycloalkyl groups optionally substituted; aryl groups optionally substituted; from linear or branched, C.sub.1-C.sub.30 alkoxy groups; polyethylenoxy groups R.sub.15—[—OCH.sub.2—CH.sub.2—].sub.q—, wherein R.sub.15 has the same meanings given above and q is an integer ranging from 1 to 4; —R.sub.16—OR.sub.17 groups, wherein R.sub.16 and R.sub.17 have the same meanings given above; —COR.sub.17 groups, wherein R.sub.17 has the same meanings above; —COOR.sub.17 groups, wherein R.sub.17 has the same meanings above; or a group —CHO, or a cyano group (—CN); R.sub.12 and R.sub.13, may be optionally linked to each other so as to form, together with the carbon atoms to which they are bonded, a saturated, unsaturated, or aromatic, cycle or a polycyclic system containing from 3 to 14 carbon atoms, optionally containing one or more heteroatoms selected from the group consisting of oxygen, sulfur, nitrogen, silicon, phosphorus, and selenium.
3. Benzodithiophene conjugated polymer of general formula (I) according to claim 1, wherein in said general formula (I): R.sub.1 is selected from linear or branched, C.sub.1-C.sub.30 alkyl groups; R.sub.2, mutually identical or different, are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.30 alkyl groups; Ar represents an electron-donor group; n is an integer ranging from 20 to 300.
4. Photovoltaic device, comprising at least one benzodithiophene conjugated polymer of general formula (I) according to claim 1.
5. Organic Thin Film Transistors, comprising at least one benzodithiophene conjugated polymer of general formula (I) according to claim 1.
6. Organic Field Effect Transistors, comprising at least one benzodithiophene conjugated polymer of general formula (I) according to claim 1.
7. Organic Light Emitting Diode, comprising at least one benzodithiophene conjugated polymer of general formula (I) according to claim 1.
8. Benzodithiophene conjugated polymer of general formula (I) according to claim 1, wherein the C.sub.1-30 alkyl groups are C.sub.2-C.sub.20 alky groups, and wherein the C.sub.1-30 alkylene groups are C.sub.2-C.sub.20 alkylene groups, wherein n is an integer ranging from 20 to 300.
9. Benzodithiophene conjugated polymer of general formula (I) according to claim 2, wherein the C.sub.1-30 alkyl groups are C.sub.2-C.sub.20 alky groups.
10. Benzodithiophene conjugated polymer of general formula (I) according to claim 2, wherein the aromatic, cycle or a polycyclic system contains from 4 to 6 carbon atoms.
11. Benzodithiophene conjugated polymer of general formula (I) according to claim 3, wherein the C.sub.1-30 alkyl groups are C.sub.2-C.sub.20 alky groups.
12. Benzodithiophene conjugated polymer of general formula (I) according to claim 3, wherein R.sub.1 is 2-octyl dodecyl group.
13. Benzodithiophene conjugated polymer of general formula (I) according to claim 3, wherein R.sub.2 is an n-octyl group.
14. Photovoltaic device of claim 4, comprising a photovoltaic cell.
15. Photovoltaic device of claim 4, comprising a photovoltaic module.
16. Photovoltaic device of claim 14, wherein the photovoltaic cell is on a rigid support.
17. Photovoltaic device of claim 14, wherein the photovoltaic cell is on a flexible support.
18. Photovoltaic device of claim 15, wherein the photovoltaic module is on a rigid support.
19. Photovoltaic device of claim 15, wherein the photovoltaic module is on a flexible support.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0038]
[0039]
[0040]
DETAILED DESCRIPTION OF THE DISCLOSURE
[0041] In accordance with a preferred embodiment of the present disclosure, in said general formula (I), Ar can be selected, for example, from the groups shown in Table 1.
TABLE-US-00001 TABLE 1
[0042] wherein: [0043] B represents a sulfur atom, an oxygen atom, a selenium atom; or it represents a N—R.sub.14 group wherein R.sub.14 represents a hydrogen atom, or it is selected from linear or branched, saturated or unsaturated, preferably C.sub.6-C.sub.26, C.sub.1-C.sub.30 alkyl groups; [0044] B′ represents a carbon atom, a silicon atom, a germanium atom; [0045] Q represents a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom; or it represents a C—R.sub.14 group wherein R.sub.14 has the same meanings given above; [0046] R.sub.11, mutually identical or different, are selected from linear or branched, saturated or unsaturated, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups; optionally substituted cycloalkyl groups; optionally substituted aryl groups; optionally substituted heteroarylic groups; linear or branched, saturated or unsaturated, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkoxy groups; polyethylenoxy groups R.sub.15—[—OCH.sub.2—CH.sub.2—].sub.q— wherein R.sub.15 is selected from linear or branched, saturated or unsaturated, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups, and q is an integer ranging from 1 to 4; —R.sub.16—OR.sub.17 groups wherein R.sub.16 is selected from linear or branched, saturated or unsaturated, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkylene groups and R.sub.17 represents a hydrogen atom, or it is selected from linear or branched, saturated or unsaturated, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups; —COR.sub.17 groups wherein R.sub.17 has the same meanings given above; —COOR.sub.17 groups wherein R.sub.17 has the same meanings given above; or they represent a —CHO group, or a cyano group (—CN); [0047] R.sub.12 and R.sub.13, mutually identical or different, represent a hydrogen atom, a fluorine atom; or they are selected from linear or branched, saturated or unsaturated, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups; optionally substituted cycloalkyl groups; optionally substituted aryl groups; linear or branched, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkoxy groups; polyethylenoxy groups R.sub.15—[—OCH.sub.2—CH.sub.2—].sub.q— wherein R.sub.15 has the same meanings given above and q is an integer ranging from 1 to 4; —R.sub.16—OR.sub.17 groups wherein R.sub.16 and R.sub.17 have the same meanings given above; —COR.sub.17 groups wherein R.sub.17 has the same meanings given above; —COOR.sub.17 groups wherein R.sub.17 has the same meanings given above; or they represent a —CHO group, or a cyano group (—CN); [0048] R.sub.12 and R.sub.13, can be optionally linked to each other so as to form, together with the carbon atoms to which they are bonded, a saturated, unsaturated, or aromatic, cycle or a polycyclic system containing from 3 to 14 carbon atoms, preferably from 4 to 6 carbon atoms, optionally containing one or more heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorus, selenium.
[0049] In accordance with a preferred embodiment of the present disclosure, in said general formula (I): [0050] R.sub.1 is selected from linear or branched, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups; preferably 2-octyl-dodecyl group; [0051] R.sub.2, mutually identical or different, preferably mutually identical, are selected from linear or branched, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups; preferably n-octyl group; [0052] Ar represents an electron-donor group, preferably thiophene; [0053] n is an integer ranging from 20 to 300.
[0054] For the purposes of the present description and the following claims, the definitions of the numerical intervals always comprise the extreme values unless otherwise specified.
[0055] For the purpose of the description and the following claims, the term “comprising” also includes also the terms “which essentially consists of” or “which consists of”.
[0056] For the purpose of the present description and the following claims, the term “C.sub.1-C.sub.30 alkyl groups” means alkyl groups having from 1 to 30 linear or branched, saturated or unsaturated, carbon atoms. Specific examples of C.sub.1-C.sub.30 alkyl groups are: methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, pentyl, ethyl-hexyl, hexyl, heptyl, n-octyl, nonyl, decyl, dodecyl, 2-octyl-dodecyl.
[0057] For the purpose of the present description and the following claims, the term “cycloalkyl groups” means cycloalkyl groups having from 3 to 30 carbon atoms. Said cycloalkyl groups can optionally be substituted with one or more groups, mutually identical or different, selected from: halogen atoms such as, for example, fluorine, chlorine, bromine, preferably fluorine; hydroxyl groups; C.sub.1-C.sub.12 alkyl groups; C.sub.1-C.sub.12 alkoxy groups; C.sub.1-C.sub.12 thioalkoxy groups; C.sub.3-C.sub.24 tri-alkylsilyl groups; polyethylene oxyl groups; cyano groups; amino groups; C.sub.1-C.sub.12 mono- or di-alkylamine groups; nitro groups. Specific examples of cycloalkyl groups are: cyclopropyl, 2,2-difluorocyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, methoxycyclohexyl, fluorocyclohexyl, phenylcyclohexyl, decalin, abietyl.
[0058] For the purpose of the present description and the following claims, the term “aryl groups” means aromatic carbocyclic groups having from 6 to 60 carbon atoms. Said aryl groups can optionally be substituted with one or more groups, mutually identical or different, selected from: halogen atoms such as, for example, fluorine, chlorine, bromine, preferably fluorine; hydroxyl groups; C.sub.1-C.sub.12 alkyl groups; C.sub.1-C.sub.12 alkoxy groups; C.sub.1-C.sub.12 thioalkoxy groups; C.sub.3-C.sub.24 tri-alkylsilyl groups; polyethylene oxyl groups; cyano groups; amino groups; C.sub.1-C.sub.12 mono- or di-alkylamine groups; nitro groups. Specific examples of aryl groups are: phenyl, methylphenyl, trimethylphenyl, methoxyphenyl, hydroxyphenyl, phenyloxyphenyl, fluorophenyl, pentafluorophenyl, chlorophenyl, bromophenyl, nitrophenyl, dimethylaminophenyl, naphthyl, phenylnaphthene, phenanthenene, anthracene.
[0059] For the purpose of the present description and the following claims, the term “heteroaryl groups” means heterocyclic aromatic, penta- or hexa-atomic groups, also benzocondensed or heterobicyclic, containing from 4 to 60 carbon atoms and from 1 to 4 heteroatoms selected from nitrogen, oxygen, sulfur, silicon, selenium, phosphorus. Said heteroaryl group can optionally be substituted with one or more groups, mutually identical or different, selected from: halogen atoms such as, for example, fluorine, chlorine, bromine, preferably fluorine; hydroxyl groups; C.sub.1-C.sub.12 alkyl groups; C.sub.1-C.sub.12 alkoxy groups; C.sub.1-C.sub.12 thioalkoxy groups; C.sub.3-C.sub.24 tri-alkylsilyl groups; polyethylene oxyl groups; cyano groups; amino groups; C.sub.1-C.sub.12 mono- or di-alkylamine groups; nitro groups. Specific examples of heteroaryl groups are: pyridine, methylpyridine, methoxypyridine, phenylpyridine, fluoropyridine, pyrimidine, pyridazine, pyrazine, triazine, tetrazine, quinoline, quinoxaline, quinazoline, furan, thiophene, hexylthiophene, bromothiophene, dibromothiophene, pyrrole, oxazole, thiazole, isooxazole, isothiazole, oxadiazole, tiadiazole, pyrazole, imidazole, triazole, tetrazole, indole, benzofuran, benzothiophene, benzooxazole, benzothiazole, benzooxadiazole, benzothiadiazole, benzopyrazole, benzimidazole, benzotriazole, triazolopyridine, triazolopyrimidine, coumarin.
[0060] For the purpose of the present description and the following claims, the term “C.sub.1-C.sub.30 alkoxy groups” means groups comprising an oxygen atom to which a linear or branched, saturated or unsaturated C.sub.1-C.sub.30 alkoxy groups is linked. Specific examples of C.sub.1-C.sub.30 alkoxyl groups are: methoxyl, ethoxyl, n-propoxyl, iso-propoxyl, n-butoxyl, iso-butoxyl, tert-butoxyl, pentoxyl, hexyloxyl, 2-ethylhexyloxyl, 2-hexyldecyloxyl, 2-octyltethradecyloxyl, 2-octyldodecyloxyl, 2-decyltetradecyloxyl, heptyloxyl, octyloxyl, nonyloxyl, decyloxyl, dodecyloxyl.
[0061] For the purpose of the present description and the following claims, the term “C.sub.1-C.sub.30 alkylene groups” means alkylene groups having from 1 to 30 linear or branched carbon atoms. Specific examples of C.sub.1-C.sub.20 alkylene groups are: methylene, ethylene, n-propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene, pentylene, ethyl-hexylene, hexylene, heptylene, octylene, nonylene, decylene, dodecylene.
[0062] For the purpose of the present description and the following claims, the term “polyethylene oxyl groups” means groups having oxyethylene units in the molecule. Specific examples of polyethylene oxyl groups are: methyloxy-ethylene oxyl, methyloxy-diethyleneoxyl, 3-oxatetraoxyl, 3,6-dioxaheptyloxyl, 3,6,9-trioxadecyloxyl, 3,6,9,12-tetraoxahexadecyloxyl.
[0063] The benzodithiophene conjugated polymer of general formula (I) object of the present disclosure can be obtained by processes known in the art.
[0064] For example, the benzodithiophene conjugated polymer of general formula (I) object of the present disclosure can be obtained by a process comprising reacting at least one benzodithiophene derivative of general formula (II):
##STR00031##
wherein R.sub.1 has the same meanings given above and X represents a halogen atom such as, for example, chlorine, fluorine, bromine, iodine, preferably, bromine; or it is selected from the —Sn(R.sub.a).sub.3 groups wherein R.sub.a, mutually identical or different, are selected from linear or branched, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups; or from B(OR.sub.b).sub.3 groups wherein R.sub.b, mutually identical or different, represent a hydrogen atom, or they are selected from linear or branched, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups, or the OR.sub.b groups together with the other atoms to which they are linked can form a heterocyclic ring having one of the following formulas:
##STR00032##
wherein R″, mutually identical or different, represent a hydrogen atom, or they are selected from linear or branched, preferably C.sub.2-C.sub.20, C.sub.1-C.sub.30 alkyl groups, with at least one compound of general formula (III):
##STR00033##
wherein R.sub.2, Ar and X, have the same meanings given above, obtaining a benzodithiophene conjugated polymer of general formula (I).
[0065] The aforesaid process can be carried out according to techniques known in the art as described, for example, by Xu J. and others, in the article “Effect of fluorination of the electrochromic performance of benzothiadiazole-based donor-acceptor copolymers”, “Journal of Materials Chemistry” (2015), Vol. 3, p. 5589-5597: further details regarding the aforesaid process can be found in the following examples.
[0066] The benzodithiophene derivative of general formula (II) can be obtained according to processes known in the art as described, for example in the US patent application US 2015/0333265 given above: further details can be found in the following examples.
[0067] The compound of general formula (III) can be obtained according to processes known in the art as described, for example, by Li S. and others, in the article “A Wide Band-Gap Polymer with a Deep Highest Occupied Molecular Orbital Level Enables 14.2% Efficiency in Polymer Solar Cells”, “Journal of the American Chemical Society” (2018), Vol. 140, p. 7159-7167: further details can be found in the following examples.
[0068] As said above, said benzodithiophene conjugated polymer of general formula (I), can be advantageously used in the construction of organic devices, in particular photovoltaic devices (or solar devices) such as, for example, photovoltaic cells (or solar cells), photovoltaic modules (or solar modules), either on a rigid support, or on a flexible support.
[0069] A further object of the present disclosure is therefore a photovoltaic device (or solar device) such as, for example, a photovoltaic cell (or solar cell), a photovoltaic module (or solar module), either on a rigid support, or on a flexible support, comprising at least one benzodithiophene conjugated polymer of general formula (I).
[0070] Furthermore, as said above, said benzodithiophene conjugated polymer of general formula (I), can be advantageously used in the construction of “Organic Thin Film Transistors” (OTFTs), “Organic Field Effect Transistors” (OFETs), or “Organic Light-Emitting Diodes” (OLEDs).
[0071] A further object of the present disclosure is therefore an “Organic Thin Film Transistors” (OTFTs), or an “Organic Field Effect Transistors” (OFETs), or an “Organic Light-Emitting Diodes” (OLEDs), comprising at least one benzodithiophene conjugated polymer of general formula (I).
[0072]
[0073] With reference to
[0080] In order to better understand the present disclosure and to put it into practice, some illustrative and non-limiting examples thereof are given below.
EXAMPLES
[0081] Characterization of the Polymers Obtained
[0082] Determination of the Molecular Weight
[0083] The molecular weight of the polymers obtained by operating in accordance with the following examples, was determined by “Gel Permeation Chromatography” (GPC) on a WATERS 150C instrument, using HT5432 columns, with trichlorobenzene eluent, at 80° C.
[0084] The weight average molecular weight (M.sub.w), the number average molecular weight (M.sub.n) and the polydispersity index (“PDI”), corresponding to the M.sub.w/M.sub.n ratio, are given.
[0085] Determination of the Optical “Band-Gap”
[0086] The polymers obtained by operating in accordance with the following examples, were characterized by UV-Vis-NIR spectroscopy to determine the energetic entity of the optical “band-gap” in solution or on thin film according to the following procedure.
[0087] In the case that the “optical band-gap” was measured in solution, the polymer was dissolved in toluene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, or other suitable solvent. The solution thus obtained was placed in a quartz cuvette and analysed in transmission by means of a double-beam and double monochromator UV-Vis-NIR spectrophotometer Perkin Elmer λ 950, in the range 200 nm-850 nm, with a 2.0 nm bandwidth, scanning speed of 220 nm/min and 1 nm step, using as a reference an identical quartz cuvette containing only the solvent used as a reference.
[0088] In the case that the “optical band-gap” was measured on thin film, the polymer was dissolved in toluene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, or other suitable solvent, obtaining a solution having a concentration equal to about 10 mg/ml, which was deposited by spin-coating on a Suprasil quartz slide. The thin film thus obtained was analysed in transmission by means of a dual-beam and double monochromator UV-Vis-NIR spectrophotometer Perkin Elmer λ 950, in the range 200 nm-850 nm, with a 2.0 nm bandwidth, scanning speed of 220 nm/min and 1 nm step, using an identical Suprasil quartz slide as such, as a reference.
[0089] The optical “band-gap” was estimated from the spectra in transmission by measuring the absorption edge corresponding to the transition from the valence band (VB) to the conduction band (CB). The intersection with the abscissa axis of the straight line tangent to the absorption band at the inflection point was used for the determination of the edge.
[0090] The inflection point (λ.sub.F, y.sub.F) was determined on the basis of the coordinates of the minimum of the spectrum in the first derivative, indicated with λ′.sub.min and y′.sub.min.
[0091] The equation of the straight line tangent to the UV-Vis spectrum at the inflection point (λ.sub.F, y.sub.F) is as follows:
y=y′.sub.minλ+y.sub.F−y′.sub.minλ′.sub.min.
[0092] Finally, from the condition of intersection with the abscissa axis ψ=0, it was obtained:
λ.sub.EDGE=(y′.sub.minλ′.sub.min−y.sub.F)/y′.sub.min.
[0093] Therefore, by measuring the coordinates of the minimum of the first derivative spectrum and the corresponding absorbance value y.sub.F from the UV-Vis spectrum, λ.sub.EDGE was obtained directly by substitution.
[0094] The corresponding energy is:
E.sub.EDGE=h.sub.vEDGE=hc/λ.sub.EDGE
wherein: [0095] h=6.626 10-34 J s; [0096] c=2.998 108 m s.sup.−1;
that is:
E.sub.EDGE=1.988 10-16 J/λ.sub.EDGE (nm).
[0097] Lastly, remembering that 1 J=6.24 1018 eV, we have:
E.sub.EDGE=1240 eV/λ.sub.EDGE (nm).
[0098] Determination of HOMO and LUMO
[0099] The determination of the HOMO and LUMO values of the polymers obtained by operating in accordance with the following examples, was carried out using the cyclic voltammetry (CV) technique. This technique makes it possible to measure the values of the potentials of formation of the radical cation and radical anion of the sample under examination. These values, inserted in a special equation, allow the HOMO and LUMO values of the polymer in question to be obtained. The difference between HOMO and LUMO makes the value of the electrochemical “band-gap”.
[0100] The values of the electrochemical “band-gap” are generally higher than the values of the optical “band-gap” since during the execution of the cyclic voltammetry (CV), the neutral compound is charged and undergoes a conformational reorganization, with an increase in the energy gap, while optical measurement does not lead to the formation of charged species.
[0101] The cyclic voltammetry (CV) measurements were carried out with an Autolab PGSTAT12 potentiostat (with GPES Ecochemie software) in a three-electrode cell. In the measurements carried out, an Ag/AgCl electrode was used as the reference electrode, a platinum wire as the counter electrode and a glassy graphite electrode as the working electrode. The sample to be analysed was dissolved in a suitable solvent and subsequently deposited, with a calibrated capillary, on the working electrode, so as to form a film. The electrodes were immersed in a 0.1 M electrolytic solution of 95% tetrabutylammonium tetrafluroborate in acetonitrile. The sample was subsequently subjected to a cyclic potential in the shape of a triangular wave. At the same time, as a function of the applied potential difference, the current, which signals the occurrence of oxidation or reduction reactions of the present species, was monitored.
[0102] The oxidation process corresponds to the removal of an electron from HOMO, while the reduction cycle corresponds to the introduction of an electron into LUMO. The potentials of formation of radical cation and radical anion were derived from the value of the peak “onset” (E.sub.onset), which is caused by molecules and/or chain segments with HOMO-LUMO levels closer to the edges of the bands. The electrochemical potentials to those related to the electronic levels can be correlated if both refer to the vacuum. For this purpose, the potential of ferrocene in vacuum, known in the literature and equal to −4.8 eV, was taken as a reference. The inter-solvent redox pair ferrocene/ferrocinium (Fc/Fc.sup.+) was selected because it has an oxide-reduction potential independent of the working solvent.
[0103] The general formula for calculating the energies of the HOMO-LUMO levels is therefore given by the following equation:
E(eV)=−4.8+[E.sub.1/2Ag/AgCl(Fc/Fc.sup.+)−E.sub.onset Ag/AgCl(polymer)]
wherein: [0104] E=HOMO or LUMO according to the entered E.sub.onset value; [0105] E.sub.1/2 Ag/AgCl=half-wave potential of the peak corresponding to the redox pair ferrocene/ferrocinium measured under the same analysis conditions as the sample and with the same trio of electrodes used for the sample; [0106] E.sub.onset Ag/AgCl=“onset” potential measured for the polymer in the anodic area when calculating HOMO and in the cathodic area when calculating LUMO.
Example 1
Preparation of 2-octyldodecyl-benzo[2,1-b; 3,4-b′]dithiophene-4-carboxylate of formula (C)
[0107] ##STR00034##
[0108] In a 250 ml flask, equipped with coolant and magnetic stirring, the following were charged, under argon flow, in the order: 3-thiopheneacetic acid (Aldrich) (0.711 g; 5 mmoles), palladium(II)acetate [Pd(OAc).sub.2] (Aldrich) (0.023 g; 0.1 mmol), triphenylphosphine [PPh.sub.3] (Aldrich) (0.052 g; 0.2 mmol), potassium carbonate [K.sub.2CO.sub.3] (Aldrich) (1.382 g; 10 mmol), anhydrous N,N-dimethylformamide (DMF) (Aldrich) (30 ml) and 2-bromothiophene-3-carbaldehyde (Aldrich) (0.955 g; 5 mmoles): the reaction mixture was heated to 110° C. and kept at said temperature, under stirring, for 12 hours. Subsequently, the reaction mixture was cooled to room temperature (25° C.) and 9-(bromomethyl)nonadecane (Sunatech) (3.614 g; 10 mmol) was added: the reaction mixture was left, under stirring, at room temperature (25° C.), for 4 hours. Subsequently, the reaction mixture was placed in a 500 ml separating funnel, diluted with a 0.1 M ammonium chloride solution (NH.sub.4Cl) (Aldrich) (3×100 ml) and extracted with ethyl acetate (Aldrich) (3×100 ml), obtaining an aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was washed to neutral with water (3×50 ml) and subsequently anidrified on sodium sulphate (Aldrich) and evaporated. The residue obtained was purified by elution on a chromatographic column of silica gel [(eluent: n-heptane/ethyl acetate, 9/1, v/v) (Carlo Erba)], obtaining 2.342 g of 2-octyldodecyl-benzo[2,1-b;3,4-b′]dithiophene-4-carboxylate of formula (C) as straw yellow oil (yield 91%).
Example 2
Preparation of 2-octyldodecyl-2,7-bis (tributylstannyl)-benzo[2,1-b;3,4-b′]dithiophene-4-carboxylate of formula (IIa)
[0109] ##STR00035##
[0110] In a 250 ml flask, equipped with magnetic stirring, the following were charged, under argon flow, in the order: 2-octyldodecyl-benzo[2,1-b;3,4-b′]dithiophene-4-carboxylate (1.029 g; 2 mmoles) obtained as described in Example 1 and anhydrous tetrahydrofuran (THF) (Aldrich) (60 ml): the reaction mixture was cooled to −78° C. and kept at said temperature, under stirring, for about 10 minutes. Subsequently, by dripping, 4.4 ml of a lithium di-iso-propylamine solution (LDA) (Aldrich) were added in a mixture tetrahydrofuran (THF) (Aldrich)/hexane (Aldrich) (1/1, v/v) 1.0 M (0.471 g; 4.4 mmoles): the reaction mixture was kept at −78° C., under stirring, for 3 hours. Subsequently, 0.678 ml of tributyltin chloride (Aldrich) (1.627 g; 5 mmoles) were added by dripping: the reaction mixture was kept at −78° C., under stirring, for 30 minutes, then brought to room temperature (25° C.) and kept at said temperature, under stirring, for 16 hours. Subsequently, the reaction mixture was placed in a 500 ml separating funnel, diluted with a 0.1 M sodium bicarbonate solution (Aldrich) (200 ml) and extracted with diethyl ether (Aldrich) (3×100 ml), obtaining an acid aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was washed to neutral with water (3×50 ml) and subsequently anidrified on sodium sulphate (Aldrich) and evaporated. The obtained residue was purified by elution on a chromatographic column of silica (Aldrich) pre-treated with a mixture of n-heptane (Aldrich)/triethylamine (TEA) (Aldrich) (9/1, v/v), [(eluent: n-heptane) (Carlo Erba)], obtaining 3.716 g of 2-octyldodecyl-2,7-bis(tributylstannyl)benzo[2,1-b;3,4-b′]dithiophene-4-carboxylate of formula (IIa) as straw yellow oil (yield 85%).
Example 3
Preparation of octyl-2-bromothiophene-3-carboxylate of formula (A)
[0111] ##STR00036##
[0112] In a 100 ml flask, equipped with coolant and magnetic stirring, the following was charged under argon flow, in the order: 2-bromo-3-thiophenecarboxylic acid (Aldrich) (2.07 g; 10 mmoles), N,N′-dicyclohexylcarbodiimide (DCC) (Aldrich) (1.032 g; 5 mmoles), 4-(dimethylamino)pyridine (DMAP) (Aldrich) (0.305 g; 2 mmoles), anhydrous dichloromethane (DCM) (Aldrich) (20 ml) and, after 5 minutes, 1-octanol (Aldrich) (1.302 g; 10 mmol) (Aldrich) was added by dripping: the reaction mixture was kept under stirring at room temperature (25° C.), for 24 hours. Subsequently, the reaction mixture was placed in a 500 ml separating funnel, diluted with distilled water (150 ml) and extracted with dichloromethane (DCM) (Aldrich) (3×100 ml), obtaining an aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was anidrified on sodium sulphate (Aldrich) and evaporated. The residue obtained was purified by elution on a chromatographic column of silica gel [(eluent: n-heptane/ethyl acetate, 9/1, (v/v) (Carlo Erba)], obtaining 2.554 g of octyl-2-bromothiophene-3-carboxylate of formula (A) as a colourless oil (yield 80%).
Example 4
Preparation of dioctyl-2,2′:5′,2″-tert-thiophene-3,3″-dicarboxylate of formula (B)
[0113] ##STR00037##
[0114] In a 100 ml flask, equipped with coolant and magnetic stirring, the following was charged, under argon flow, in the order: octyl-2-bromothiophene-3-carboxylate obtained as described in Example 3 (1.596 g; 5 mmoles), anhydrous toluene (Aldrich) (30 ml), 2,5-bis (trimethylstannyl)thiophene (Aldrich) (0.819 g; 2 mmoles) (Aldrich), tris(dibenzylideneacetone)dipalladium(0) [Pd.sub.2(dba).sub.3] (Aldrich) (0.055 g; 0.06 mmol) and tri(o-tolyl)phosphine [P(o-tol).sub.3] (Aldrich) (0.061 g; 0.2 mmol): the reaction mixture was heated to 115° C. and kept at said temperature, under stirring, for 5 hours. Subsequently, the reaction mixture was concentrated by rotovapor and the residue obtained was purified by elution on a chromatographic column of silica gel [(eluent: n-heptan/ethyl acetate, 9/1, v/v) (Carlo Erba)], obtaining 1.054 g of dioctyl-2,2′:5′,2″-tert-thiophene-3,3″-dicarboxylate of formula (B) as straw yellow oil (yield 94%).
Example 5
Preparation of dioctyl-5,5″-dibromo-2,2′:5′,2″-tert-thiophene-3,3″-Dicarboxylate of Formula (IIIa)
[0115] ##STR00038##
[0116] In a 100 ml flask, equipped with magnetic stirring, the following was charged, under argon flow, in the order: dioctyl-2,2′:5′,2″-tert-thiophene-3,3″-dicarboxylate of formula (B) obtained as described in Example 4 (1.009 g; 1.8 mmoles), anhydrous chloroform (Aldrich) (20 ml) and N-bromosuccinimide (Aldrich) (0.365 g; 2.05 mmoles): the reaction mixture was kept, under stirring, at room temperature (25° C.), for 20 hours. Subsequently, the reaction mixture was placed in a 500 ml separating funnel, diluted with distilled water (150 ml) and extracted with dichloromethane (DCM) (Aldrich) (3×100 ml), obtaining an aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was anidrified on sodium sulphate (Aldrich) and evaporated. The residue obtained was purified by elution on a chromatographic column of silica gel [(eluent: n-heptane/dichloromethane, 9/1, v/v (Carlo Erba)], obtaining 1.164 g of dioctyl-5,5″-dibromo-2,2′:5′,2″-tert-thiophene-3,3″-dicarboxylate of formula (IIIa) as yellow-orange oil (90% yield).
Example 6
Preparation of the Benzodithiophene Conjugated Polymer of Formula (Ia)
[0117] ##STR00039##
[0118] In a 100 ml flask, equipped with magnetic stirring, thermometer and coolant, the following was charged, under argon flow, in the order: dioctyl-5,5″-dibromo-2,2′:5′,2″-tert-thiophene-3,3″-dicarboxylate of formula (IIIa) obtained as described in Example 5 (0.719 g; 1.001 mmoles), toluene (Aldrich) (80 ml), 2-octyldodecyl-2,7-bis(tributylstannyl)benzo[2,1-b;3,4-b′]dithiophene-4-carboxylate of formula (IIa) obtained as described in Example 2 (1.2 g; 1.097 mmoles), tris(dibenzylideneacetone)dipalladium (0) [Pd.sub.2(dba).sub.3] (Aldrich) (0.018 g; 0.02 mmol) and tris(o-tolyl)phosphine [P(o-tol).sub.3] (Aldrich) (0.031 g; 0.1 mmoles): the reaction mixture was heated to 100° C. and kept at said temperature, under stirring, for 24 hours. The colour of the reaction mixture turned dark red after 3 hours and turned dark brick red at the end of the reaction (i.e. after 24 hours). Subsequently, after cooling to room temperature (25° C.), the reaction mixture obtained was placed in methanol (Aldrich) (300 ml) and the precipitate obtained was subjected to sequential extraction in a Soxhlet apparatus with methanol (Aldrich), acetone (Aldrich), n-heptane (Aldrich) and, finally, chloroform (Aldrich). The residue remained inside the extractor was dissolved in chlorobenzene (Aldrich) (50 ml) at 80° C. The hot solution was precipitated in methanol (Aldrich) (300 ml). The obtained precipitate was collected and dried under vacuum at 50° C. for 16 hours, obtaining 1.014 g of a dark violet solid product (95% yield), corresponding to the benzodithiophene conjugated polymer of formula (Ia).
[0119] Said solid product was subjected to the above characterizations obtaining the following data: [0120] (M.sub.w)=85617 Dalton; [0121] (PDI)=2.2384. [0122] (λ.sub.EDGE sol.)=610 nm; [0123] (λ.sub.EDGE film)=620 nm; [0124] E.sub.g.opt.sol.=2.01 eV; [0125] E.sub.g.opt.film=1.99 eV; [0126] (HOMO)=−5.42 eV
Example 7 (Comparative)
Solar Cell Comprising Regioregular Poly-3-Hexylthiophene (P3HT)
[0127] For this purpose, a polymeric solar cell with inverted structure was used, schematically represented in
[0128] For this purpose, a polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec Company—Hong Kong), previously subjected to a cleaning procedure consisting of a manual cleaning, rubbing with a lint-free cloth soaked in a detergent diluted with tap water. The substrate was then rinsed with tap water. Subsequently, the substrate was thoroughly cleaned using the following methods in sequence: ultrasonic baths in (i) distilled water plus detergent (followed by manual drying with a lint-free cloth); (ii) distilled water [followed by manual drying with a lint-free cloth]; (iii) acetone (Aldrich) and (iv) iso-propanol (Aldrich) in sequence. In particular, the substrate was placed in a beaker containing the solvent, placed in an ultrasonic bath, kept at 40° C., for a treatment of 10 minutes. After treatments (iii) and (iv), the substrate was dried with a compressed nitrogen flow.
[0129] Subsequently, the glass/ITO was further cleaned in an air plasma device (Tucano type—Gambetti), immediately before proceeding to the next step.
[0130] The substrate thus treated was ready for the deposition of the cathodic buffer layer. For this purpose, the zinc oxide (ZnO) buffer layer was obtained starting from a 0.162 M solution of the complex [Zn.sup.2+]-ethanolamine (Aldrich) in butanol (Aldrich). The solution was deposited by rotation on the substrate operating at a rotation speed equal to 600 rpm (acceleration equal to 300 rpm/s), for 2 minutes and 30 seconds, and subsequently at a rotation speed equal to 1500 rpm, for 5 seconds. Immediately after deposition of the cathodic buffer layer, zinc oxide formation was obtained by thermally treating the device at 140° C. for 5 minutes on a hot plate in ambient air. The cathodic buffer layer thus obtained had a thickness equal to 30 nm and was partially removed from the surface with 0.1 M acetic acid (Aldrich), leaving the layer only on the desired surface.
[0131] The active layer was deposited, comprising regioregular poly-3-hexylthiophene (P3HT) (Plexcore OS) and methyl ester of the [6,6]-phenyl-C.sub.61-butyric acid (PCBM) (Aldrich), on the cathodic buffer layer thus obtained by “spin coating” of a 1/0.8 (v/v) solution in o-dichlorobenzene (Aldrich) with a P3HT concentration equal to 10 mg/ml which had been kept under stirring overnight, operating at a rotation speed of 300 rpm (acceleration equal to 255 rpm/s), for 90 seconds. The thickness of the active layer was found to be 250 nm.
[0132] On the active layer thus obtained, the anodic buffer layer was deposited, which was obtained by depositing molybdenum oxide (MoO.sub.3) (Aldrich) through a thermal process: the thickness of the anodic buffer layer was equal to 10 nm. A silver (Ag) anode, having a thickness equal to 100 nm, was deposited on the anodic buffer layer by vacuum evaporation, appropriately masking the area of the device in order to obtain an active area equal to 25 mm.sup.2.
[0133] The depositions of the anodic buffer layer and of the anode were carried out in a standard evaporation chamber under vacuum containing the substrate and two evaporation vessels equipped with a heating resistance containing 10 mg of molybdenum oxide (MoO.sub.3) in powder and 10 (Ag) silver shots (diameter 1 mm-3 mm) (Aldrich), respectively. The evaporation process was carried out under vacuum, at a pressure of about 1×10.sup.−6 bar. The molybdenum oxide (MoO.sub.3) and silver (Ag), after evaporation, are condensed in the unmasked parts of the device.
[0134] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.
[0135] The electrical characterization of the device obtained was carried out in a controlled atmosphere (nitrogen) in a “glove box”, at room temperature (25° C.). The current-voltage curves (I-V) were acquired with a Keithley® 2600A multimeter connected to a personal computer for data collection. The photocurrent was measured by exposing the device to the light of an ABET SUN® 2000-4 solar simulator, capable of providing 1.5G AM radiation with an intensity equal to 100 mW/cm.sup.2 (1 sun), measured with a Ophir Nova® II powermeter connected to a 3A-P thermal sensor. The device, in particular, is masked before said electrical characterization, so as to obtain an effective active area equal to 16 mm.sup.2: Table 1 shows the four characteristic parameters as average values.
Example 8 (Disclosure)
Solar Cell Disclosure Comprising the Benzodithiophene Conjugated Polymer of
[0136] Formula (Ia) A polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec Company—Hong Kong), previously subjected to a cleaning procedure operating as described in Example 7.
[0137] The deposition of the cathodic buffer layer and the deposition of the anodic buffer layer were carried out as described in Example 7; the composition of said cathodic buffer layer and the composition of said anodic buffer layer are the same as the ones in Example 7; the thickness of said cathodic buffer layer and the thickness of said anodic buffer layer are the same as the ones in Example 7.
[0138] The active layer, comprising the benzodithiophene conjugated polymer of formula (Ia) obtained as described in Example 6 and methyl ester of the [6,6]-phenyl-C.sub.61-butyric acid (PCBM) (Aldrich), was deposited on the cathodic buffer layer thus obtained by spin coating of a 1/1.5 (v/v) solution in o-dichlorobenzene (Aldrich) with a conjugated polymer concentration of formula (Ia) equal to 18 mg/ml which had been kept under stirring overnight, operating at a rotation speed equal to 5000 rpm (acceleration equal to 2500 rpm/s), for 30 seconds. The thickness of the active layer was found to be 60 nm.
[0139] The deposition of the silver (Ag) anode was carried out as described in Example 7: the thickness of said silver anode (Ag) is the same as the one given in Example 7.
[0140] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.
[0141] The electrical characterization of the obtained device was carried out as described in Example 7: Table 1 shows the four characteristic parameters as average values.
[0142]
[0143]
TABLE-US-00002 TABLE 1 V.sub.OC.sup.(2) J.sub.SC.sup.(3) PCE.sub.av.sup.(4) EXAMPLE FF.sup.(1) (V) (mA/cm.sup.2) (%) 7 (comparative) 0.57 0.56 10.10 3.30 8 (disclosure) 0.65 0.92 8.25 4.97 .sup.(1)FF (Fill Factor) is calculated according to the following equation: