Diamondoid compound

Abstract

The present invention relates to a compound of formula I D 1 -Z D -(A 1 -Z 1 ) r -B 1 -(Z 2 -A 2 ) s -Sp-G (I) where the groups and parameters occurring have the meanings given in claim 1 to its use for the formation of molecular layers, in particular self-assembled monolayers (SAMs), on diamondoid compounds represented by, for the process for fabricating switching elements for memory resistor devices comprising such molecular layers, and for devices of memristors comprising such switching elements.

Description

Technical Field

[0001] The present invention relates to the use of diamondoid compounds for the formation of molecular layers, particularly self-assembled monolayers (SAMs), to a process for fabricating switching elements for memory devices comprising such molecular layers, and to devices of memristors comprising such switching elements.

Background Art

[0002] In computer technology, there is a need for storage media that enable rapid write and read access to stored information. Solid-state memory or semiconductor memory, in particular, enables the realization of a storage medium that is extremely fast and reliable because no moving parts are required. Currently, dynamic random access memory (DRAM) is mainly used. DRAM enables rapid access to stored information, but this information must be updated regularly, meaning that the stored information is lost when the power is turned off.

[0003] Also, the prior art discloses non-volatile semiconductor memories such as flash memory or magnetic random access memory (MRAM) that retain information even after the power is turned off. The disadvantages of flash memory are that write access is relatively slow and that the memory cells of flash memory cannot be erased indefinitely. The lifespan of flash memory is typically limited to a maximum of one million read / write cycles. MRAM can be used in the same way as DRAM and has a long lifespan, but the spread of this type of memory has not progressed due to the difficulty of the manufacturing process.

[0004] A further alternative is a memory that operates based on memristors. The term memristor is a contraction of "memory" and "resistor" and represents a component whose electrical resistance can be reproducibly changed between a high electrical resistance and a low electrical resistance. Each state (high resistance or low resistance) is retained even in the absence of a supply voltage, meaning that a non-volatile memory can be achieved by memristors.

[0005] For example, WO2012 / 127542A1 and US2014 / 008601A1 disclose an organic molecule memory having two electrodes and an active region disposed between the two electrodes. The active region has a molecular layer of a conductive aromatic alkyne, and its conductivity can be changed under the influence of an electric field. A similar component based on a redox-active bipyridinium compound has been proposed in US2005 / 0099209A1.

[0006] Known memories based on changes in conductivity or resistance have the drawback that free radical intermediates formed by the flow of current through the molecules of the molecular layer are prone to decomposition processes in principle, which is harmful to the lifespan of the components.

[0007] WO2018 / 007337A2 describes an improved switching layer that utilizes a non-redox-active molecular layer containing a bipolar compound linked to a substrate via an aliphatic spacer group, where the compound is reversibly switched by the application of an electric field that causes reorientation of the molecular dipole, thus enabling a low resistance state and a high resistance state depending on the respective orientation of the molecules.

[0008] To obtain an electrically switchable tunnel junction from an organic compound with a three-dimensionally flexible dipole, a molecular layer sandwiched between two conductive electrodes is required. The formation of this molecular layer on the electrodes is achieved either by spin coating or by dip coating from an organic solvent. The basic principle of the resulting memory device is described in WO2016 / 110301A1 and WO2018 / 007337A2. To limit the formation of a short circuit between the upper and lower electrodes, the monolayer should be as tight as possible without pinholes that would allow penetration of the upper electrode material during its film formation process. Also, a material that forms a molecular layer of acceptable quality within a very short film formation time is strongly required.

[0009] Photolithography is generally used for the formation of the electrodes. A major problem with state-of-the-art molecular layers is their hydrophobicity, typically exhibiting a water contact angle (CWA) of approximately 104°. Most photoresists require that the CWA of the substrate be less than this value. As the CWA increases, uncontrolled dewetting occurs during spin coating of the photoresist solution, resulting in non-uniform film formation. This hinders the construction of the electrode structure on the molecular layer. A CWA significantly below 100° is required for uniform spreading and good adhesion of the photoresist and lift-off resist. At the same time, the molecular layer surface should have a densely packed and low alkane-like chemical reactivity.

[0010] The problem to be solved by the present invention is to provide an improved material for the fabrication of switchable molecular layers that is compatible with processes commonly used in the semiconductor industry.

Summary of the Invention

[0011] To solve the problem, a compound represented by formula I shown below is provided, which contains a terminal diamondoid moiety connected to a polar ring element that can be self-organized onto a substrate by using an anchor group attached to the polar ring via a flexible spacer group.

[0012] The present invention further relates to a process for the manufacture of a switching element comprising a molecular layer obtainable from one or more compounds of formula I. The present invention further relates to a memristor device comprising the switching element.

[0013] Preferred embodiments are the subject matter of the dependent claims and can also be taken from the description.

[0014] The present invention relates to formula I D 1 -Z D -(A 1 -Z 1 ) r -B 1 -(Z 2 -A 2 ) s -Sp-G (I) a compound represented by formula: wherein D 1 represents a diamondoid radical, preferably one derived from a lower diamondoid, most preferably one selected from the group consisting of adamantyl, diamantyl, and triamantyl, wherein one or more H atoms may be replaced by F and in each case may be replaced by an optionally fluorinated alkyl, alkenyl or alkoxy having up to 12 C atoms, especially

Chemical formula

Chemical formula

Chemical formula

[0015] The molecular layer obtained from the compound represented by formula I is distinguished by close packing and low CWA, and enables the fabrication of switching elements for memristor devices that can be patterned by photolithography using standard industrial processes. Surprisingly, the molecular layer is further distinguished by a high break down bias.

Brief Description of the Drawings

[0016] The drawings are

Figure 1

Figure 2

[0017] The term "diamondoid" refers to substituted and unsubstituted cage compounds of the adamantane series including adamantane, diamantane, triamantane, tetramantane, pentamantane, hexamantane, heptamantane, octamantane, etc., and all of their isomers and stereoisomers. The compounds have a "diamondoid" topology, which means that their carbon atom arrangements are superposable on fragments of the face-centered cubic diamond lattice. Substituted diamondoids from the beginning of the series preferably carry from 1 to 4 independently selected alkyl or alkoxy substituents.

[0018] Diamondoids include "lower diamondoids" and "higher diamondoids" (as these terms are defined herein), as well as mixtures of any combination of lower and higher diamondoids. The term "lower diamondoid" refers to adamantane, diamantane, and triamantane, as well as unsubstituted and substituted derivatives of any and / or all of adamantane, diamantane, and triamantane. These lower diamondoid components do not exhibit isomerism or chirality and are readily synthesized and distinguishable from "higher diamondoids". The term "higher diamondoid" refers to any and / or all substituted and unsubstituted tetramantane components; any and / or all substituted and unsubstituted pentamantane components; any and / or all substituted and unsubstituted hexamantane components; any and / or all substituted and unsubstituted heptamantane components; any and / or all substituted and unsubstituted octamantane components; as well as mixtures thereof, and isomers and stereoisomers of tetramantane, pentamantane, hexamantane, heptamantane, and octamantane. Adamantane chemistry has been reviewed by Fort, Jr. et al. in "Adamantane: Consequences of the Diamondoid Structure," Chem. Rev. vol. 64, pp. 277-300 (1964). Adamantane is the smallest member of the diamondoid series and may be considered as a single cage crystal subunit. Diamantane contains two subunits, triamantane contains three, tetramantane contains four, and so on. While there is only one isomeric form of adamantane, diamantane, and triamantane, tetramantane has four different isomers (two of which represent enantiomeric pairs), i.e., four different possible ways or arrangements of four adamantane subunits. The number of possible isomers increases non-linearly with each successive member of the diamondoid series such as pentamantane, hexamantane, heptamantane, octamantane, and so on.Commercially available adamantane has been studied extensively. Research has been conducted in many areas such as the thermodynamic stability, functionalization, and properties of adamantane-containing materials. As an example, Schreiber et al., New J. Chem., 2014, 38, 28-41 describes the synthesis and application of functionalized diamondoids for forming large-area SAMs on silver and gold surfaces. In K. T. Narasimha et al., Nature Nanotechnology 11, March 2016 page 267-273, it is described that a monolayer of diamondoid effectively imparts enhanced field emission properties to a metal surface due to a significant decrease in the work function of the metal.

[0019] As used herein, an anchor group is a functional group that adsorbs or binds a compound to a substrate surface by physical adsorption, chemisorption, or by a chemical reaction.

[0020] The spacer group referred to in the present invention is a flexible chain between the bipolar part and the anchor group, which results in the separation between these secondary structures and at the same time improves the mobility of the bipolar part after binding to the substrate due to its flexibility.

[0021] The spacer group can be branched or linear. A chiral spacer is branched and optically active.

[0022] As used herein, alkyl is linear or branched and has 1 to 15 C atoms, preferably linear, and, unless otherwise specified, has 1, 2, 3, 4, 5, 6, or 7 C atoms and, as a result, is preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, or heptyl.

[0023] In this specification, the alkoxy radical is linear or branched and contains 1 to 15 carbon atoms. It is preferably linear and, unless otherwise specified, has 1, 2, 3, 4, 5, 6 or 7 carbon atoms and, as a result, is preferably methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.

[0024] In this specification, the alkenyl radical is preferably an alkenyl radical having 2 to 15 carbon atoms, which is linear or branched and contains at least one C—C double bond. It is preferably linear and has 2 to 7 carbon atoms. As a result, it is preferably vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl. When the two carbon atoms of the C—C double bond are substituted, the alkenyl radical can be in the form of E and / or Z isomers (trans / cis). In general, each E isomer is preferred. Among the alkenyl radicals, prop-2-enyl, but-2- and -3-enyl, and pent-3- and -4-enyl are particularly preferred.

[0025] In this specification, alkynyl is meant to be an alkynyl radical having 2 to 15 carbon atoms, which is linear or branched and contains at least one C—C triple bond. 1- and 2-propynyl and 1-, 2- and 3-butynyl are preferred.

[0026] In formula I, preferred aryl groups are derived, for example, from the parent structures benzene, naphthalene, tetrahydronaphthalene, 9,10-dihydrophenanthrene, fluorene, indene and indane.

[0027] In formula I, preferred heteroaryl groups are, for example, 5-membered rings such as furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole and 1,3,4-thiadiazole; 6-membered rings such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine and 1,2,3-triazine; or fused rings such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, benzoxazole, naphthoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazothiophene, 2H-chromene (2H-1-benzopyran), 4H-chromene (4H-1-benzopyran) and coumarin (2H-chromen-2-one); or combinations of these groups.

[0028] In formula I, preferred alicyclic groups are cyclobutane, cyclopentane, cyclohexane, cyclohexene, cycloheptane, decahydronaphthalene, bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, spiro[3.3]heptane and octahydro-4,7-methanoindane.

[0029] In formula I, preferred heteroaliphatic groups are tetrahydrofuran, dioxolane, tetrahydrothiophene, pyran, dioxane, dithiane, silinane, piperidine and pyrrolidine.

[0030] A 1 and A 2 are, in each occurrence, the same or different, more preferably the following group: a) 1,4-phenylene, wherein, additionally, one or two CH groups may be replaced by N, and wherein, additionally, one or more H atoms may be replaced by Y, b) a group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, wherein, additionally, one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, and wherein, additionally, one or more H atoms may be replaced by Y, and c) a group consisting of 1,3-dioxolane-2,4-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, 1,4-bicyclo[2.2.2]octanediy, piperidine-1,5-diyl and thiophene-2,5-diyl, wherein, additionally, one or more H atoms may be replaced by Y, wherein Y has the meaning shown in formula I above and preferably represents F, Cl, CN or CF3, and is selected from

[0031] In formula I, a preferred spacer group Sp is selected from formula Sp'-X' such that the radical G-Sp- corresponds to formula G-Sp'-X'- and the radical D 1 -Sp- corresponds to formula D 1 -Sp’-X’, where Sp' represents a straight-chain or branched alkylene having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein, additionally, one or more non-adjacent CH2 groups are independently of each other, such that O and / or S atoms are not directly linked to each other, -O-, -S-, -NH-, -NR 0 -, -SiR 00 R 000 -, -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -NR 0 -CO-O-, -O-CO-NR 0 -, -NR 0 -CO-NR 0- may also be replaced by -CH=CH- or -C≡C- respectively, X' is -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 00 -, -NR 00 -CO-, -NR 00 -CO-NR 00 -, -OCH2-, -CH2O-, -SCH2-, -CH2S-,-CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 00 -, -CY x =CY x‘ -, -C≡C-, -CH=CH-COO-, -OCO-CH=CH- or a single bond, R 0 、R 00 and R 000 each independently represents H or alkyl having 1 to 12 C atoms, and Y x and Y x‘ each independently represents H, F, Cl or CN. X' is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 0 - or a single bond.

[0032] Preferred group Sp' is -(CH2) p1 -, -(CF2) p1 -, -(CH2CH2O) q1 -CH2CH2-, -(CF2CF2O) q1 -CF2CF2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 00 R 000 -O) p1- where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 00 and R 000has the meaning shown above.

[0033] Particularly preferred groups -X'-Sp'- are, for example, -(CH2) p1 -, -O-(CH2) p1 -, -(CF2) p1 -,-O(CF2) p1 -, -OCO-(CH2) p1 - and -OC(O)O-(CH2) p1 -, where p1 has the meaning shown above.

[0034] Particularly preferred groups Sp' are, for example, in each case, linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, perfluoroethylene, perfluoropropylene, perfluorobutylene, perfluoropentylene, perfluorohexylene, perfluoroheptylene, perfluorooctylene, perfluorononylene, perfluorodecylene, perfluoroundecylene, perfluorododecylene, perfluorooctadecylene, ethyleneoxyethylene, methylenoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.

[0035] Particularly preferred group X’ is -O- or a single bond.

[0036] Particularly preferred sub-formulas of formula I are sub-formulas Ia to If: D 1 -Z D -B 1 -Sp-G Ia D 1 -Z D -(A 1 -Z 1 )-B 1 -Sp-G Ib D 1 -Z D -(A 1 -Z1 ) 2-B 1 -Sp-G Ic D 1 -Z D -B 1 -(Z 2 -A 2 ) -Sp-G Id D 1 -Z D -B 1 -(Z 2 -A 2 ) 2-Sp-G Ie D 1 -Z D -(A 1 -Z 1 ) -B 1 -(Z 2 -A 2 ) -Sp-G If wherein D 1 , A 1 , A 2 , B 1 , Z D , Z 1 , Z 2 , Sp and G have the meanings shown above.

[0037] In formula I and its sub-formulas, very preferably, A 1 and A 2 are the same or different,

Chem.

Chem.

[0038] In a further preferred embodiment, in the compounds of formulas Ia - If, Sp represents an unbranched 1,ω-perfluoroalkylene having 1 - 12 C atoms, where D 1 A 1 A 2 B 1 Z 1 Z 2 and G have the meanings given above.

[0039] Highly particularly preferred sub-formulas of formula I are sub-formulas Ia, Ib and Id, and in particular, the following compounds:

Chemical formula

Chemical formula

[0040] Also covered by this specification are compounds of formula I, wherein the group -C v H 2v - is replaced by -C v F 2v - in sub-formulae Ia-1 to Ia-12, Ib-1 to Ib-24, and Id-1 to Id-18.

[0041] According to another aspect of the invention, there is provided a chiral non-racemic compound of formula I.

[0042] The molecular layer obtained from the chiral compound represented by formula I enables a memory device with significantly reduced stochastic noise and faster switching, which reduces the read and write error rates, which has a positive effect on energy efficiency. In addition, an increased tunneling current is observed, enabling integration into smaller junction sizes.

[0043] Preferably, the chiral compound has an enantiomeric excess (ee) of more than 50%, preferably 80%, 90%, more than 95%, more preferably more than 97%, especially more than 98%.

[0044] Chirality is achieved by the branched chiral group Sp represented by the above formula I having one or more, preferably one or two, most preferably one asymmetrically substituted carbon atom (or: asymmetric carbon atom, C*, hereinafter referred to as Sp*).

[0045] In Sp*, the asymmetric carbon atom is preferably linked to two differently substituted carbon atoms, a hydrogen atom, and a substituent selected from a halogen group (preferably F, Cl, or Br), an alkyl or alkoxy (each with 1 to 5 carbon atoms in each case) and CN.

[0046] The chiral organic radical Sp* preferably has the formula

Chemical formula

[0047] Z in formula I D In the embodiment where it is a chiral non-racemic spacer group, the group D 1 -Sp* preferably has the formula

Chemical formula

[0048] The compounds represented by general formula I are prepared by methods known per se, precisely under the reaction conditions known and suitable for said reaction, as described in the literature (for example in standard works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart). Here, variants known per se can be used, which are not mentioned in more detail herein. The chiral groups R* and Sp* are described in A. Taugerbeck, Ch. Booth, Design and Synthesis of Chiral Nematic Liquid Crystals, in: Handbook of Liquid Crystals, Volume 3, Part III, Chapter 14, Wiley VCH, Weinheim, 2014 and can preferably be synthesized according to the syntheses described in this specification and the literature cited herein.

[0049] If desired, the starting materials can also be formed in situ by immediately converting them further into the compounds represented by general formula I without isolating them from the reaction mixture.

[0050] Preferred synthetic routes towards the compounds according to the invention are shown in the following scheme and are further depicted using examples. The synthesis can be adapted, in particular, to the compounds represented by general formula I desired, by the choice of suitable starting materials.

[0051] Suitable precursors for the diamondoid moiety are the corresponding diamondoid alcohols and hydroxyalkyl derivatives, which are readily available by the methods described in H. Schwertfeger et al., Angew. Chem. Int. Ed. 2008, 47, 1022-1036; W. L. Yang et al., Science 2007, 316, 1460-1462; W. A. Clay et al., Nano Lett. 2009, 9, 57-61; et al., Langmuir 2013, 29, 9790-9797; K. T. Narasimha et al., Nat. Nanotechnol. 2015, 11, 267-272; A. A. Fokin et al., Synthesis 2017, 49, 2003-2008; M. A. Gunawan et al., Nanoscale 2015, 7, 1956-1962; P. Kahl et al., Synthesis 2014, 46,787-798; N. A. Fokina et al., Synthesis 2012, 44, 259-264; A. A. Fokin, et al., Chem. Eur. J. 2009, 15, 3851-3862.

[0052] The attachment of the diamondoid moiety to the main structure of the monolayer precursor can be achieved, for example, by the following methods: direct derivatization of phenol with a diamondoid tertiary alcohol (see, A. Koperniku et al., Lett. Org. Chem. 2016, 13, 171 - 176); reaction of aryl halides by Negishi coupling with diamondoid zinc (see, C. Saemann et al., Org. Lett. 2014, 16, 2418 - 2421); or from phenol with activated alkyldiamondoid via nucleophilic substitution (see, R. G. Booth et al., J. Med. Chem. 1987, 30, 1218 - 1224; Angew. Chem. Int. Ed., 2014, 53, 9669 - 9673).

[0053] The above synthetic approach is depicted as an example using adamantane derivatives in the following scheme. The reaction is also suitable for the conversion of higher diamondoids.

[0054] Typical preferred building blocks are, for example, available from adamantyl halides 1 (Scheme 1), preferably adamantyl bromide, which can be reacted with phenol to provide adamantylphenol (3). Adamantyl halides are also used for the formation of zinc reagents (4) according to Ch. Saemann et al., Org. Lett. 2014, 16, 2418 - 2421. These reagents undergo a Negishi coupling reaction with a wide range of generally known aromatic compounds to provide adamantylaryl derivatives 5.

[0055] Scheme 1

Number

[0056] Readily available adamantyl alcohol 6 can be converted to aryl derivative 5 by a Friedel-Crafts reaction in the presence of trifluoroacetic acid (see Koperniku, Ana et al., Letters in Organic Chemistry, 13(3), 171-176; 2016). Alcohol 7 can be used, for example, for the derivatization of phenol in a Williamson ether synthesis to provide compound 8.

[0057] Scheme 2

Number

[0058] The known alkyne 9 (Scheme 3) can also be converted to phenylacetylene 10 by the above-mentioned Negishi coupling and is a versatile building block for further well-known conversions, for example, to phenol 11.

[0059] Scheme 3

Number

[0060] Phenol 3 provides access to cyclohexyl derivatives by hydrogenation (Scheme 4).

[0061] Scheme 4

Number

[0062] Anchor groups can be attached to building blocks by preferred transformations known from the prior art mentioned above and as shown in the examples. Other typical transformations are illustrated in Scheme 5, for example phenol 3 can be alkylated with ω-bromo carboxylic esters, followed by saponification to provide compounds with carboxylic acid anchor groups (14), or etherification with protected alcohols such as (2,2-dimethyl-1,3-dioxan-5-yl)methanol to produce alcohols such as compound 16.

[0063] Scheme 5

number

[0064] The present invention further comprises at least the following steps: a) preparation of a first electrode having a surface; b) depositing a monolayer comprising one or more compounds of formula I on the surface of a first electrode; c) Application of the second electrode The present invention relates to a process for the manufacture of a switching element according to the invention, comprising:

[0065] The deposition of the monolayer is carried out using the pure substances or from solution, preferably from solution. Suitable deposition methods and solvents are known to the person skilled in the art; examples are spin-coating or dip-coating.

[0066] In accordance with another aspect of the invention, the monolayer is fabricated from one or more compounds of formula I, wherein the anchor group G is -SO2OR V , -OP(O)(OR V )2, -PO(OR V )2, -C(OH)(PO(OR V )2)2, -COOR V Or -Si(OR V )3, where R Vrepresents an alkyl having 1 to 20 C atoms, preferably a secondary or tertiary alkyl having at most 20 C atoms. These compounds are distinguished by particularly high solubility and are well-suited for industrial processes such as spin coating. In addition, these compounds can be processed by vapor deposition. The compounds serve as precursors for the corresponding free acids, which are obtained in situ by heat treatment of the compounds after film formation on the first electrode. The first electrode is then heated to a temperature between 60 °C and 300 °C, preferably between 100 °C and 250 °C, particularly between 140 °C and 180 °C.

[0067] In a preferred embodiment, the substrate is annealed after film formation of the molecular layer. The annealing is carried out at a temperature above 20 °C and below 300 °C, preferably above 50 °C and below 200 °C, particularly preferably above 90 °C and below 150 °C. The annealing time is 1 to 48 hours, preferably 4 to 24 hours, particularly preferably 8 to 16 hours.

[0068] The molecular layer of the present invention is a layer of an electrically insulating, non-conductive and non-semiconducting organic compound.

[0069] The molecular layer preferably contains molecules represented by formula I, and particularly preferably consists of molecules represented by formula I.

[0070] The thickness of the layer is preferably 10 nm or less, particularly preferably 5 nm or less, and extremely particularly preferably 2 nm or less.

[0071] The molecular layer may consist of one, two, three or more molecular layers containing the compound represented by formula I.

[0072] The molecular layer employed according to the present invention is preferably a molecular monolayer.

[0073] In one aspect, the molecular layer is a self-assembled monolayer (SAM).

[0074] The production of self-assembled monolayers is known to those skilled in the art; for example, it has been reviewed in A. Ulman, Chem. Rev. 1996, 96, 1533-1554.

[0075] In a further aspect, the molecular layer is bonded to the substrate by chemisorption, in particular by an addition reaction or a condensation reaction.

[0076] In a further aspect, the molecular layer is bonded to the substrate by physical adsorption.

[0077] The coverage rate of the substrate is preferably 90% to 100%, particularly preferably 95% or more to 100%, and extremely particularly preferably 98% or more to 100%.

[0078] In a further aspect, the molecular layer is covered with a further layer of 1 to 10, preferably 1 to 5, and particularly preferably 1 to 3, organic or inorganic adsorbates. Suitable layers include, for example, dielectrics such as oxidizing, fluorinating or nitriding materials such as TiO2, Al2O3, HfO2, SiO2, LiF and Si3N4, or metals such as Pt, Pd, Pb, Au, Ag, Cu, Al and Mg, and their eutectic compounds such as PdAu20:80. Such layers can be constructed with a thickness of several nanometers by defined and highly precise film formation, for example by an ALD (atomic layer deposition) process.

[0079] The molecules of the molecular layer are preferably covalently bonded to the substrate. The bonding is carried out by known methods familiar to those skilled in the art, for example by an addition reaction of a compound represented by formula I, or by esterification with a hydroxyl group arranged on the surface of the substrate.

[0080] For an addition reaction, a suitable substrate, preferably a silicon surface (after the corresponding pretreatment with an aqueous NH4F solution), can be treated, for example, to obtain a hydrogen-terminated surface. The surface thus treated can then be directly treated at a high temperature under oxygen exclusion with either a suitable liquid compound of formula I or a solution of the compound of formula I in a suitable solvent. According to this aspect of the invention, the group G in formula I preferably represents -CH=CH2.

[0081] For a condensation reaction, a suitable substrate, preferably a silicon surface, can be treated with an oxygen plasma, for example, to obtain a hydrophilic oxidizing surface where hydroxyl groups aggregate. The surface thus treated can then be directly reacted at a high temperature with either a suitable liquid compound of formula I or a solution of the compound of formula I in a suitable solvent. It is clear that this type of oxidizing surface serves only for surface modification via a condensation reaction for possible derivatization purposes and does not become an insulator layer in the true sense. Due to its thickness of about 1 nm, a sufficiently large tunnel current through this oxidizing surface is possible.

[0082] In the switching element according to the invention, the molecules of the molecular layer are bonded to the substrate or to an intermediate layer positioned between the molecular monolayer and the substrate. The substrate according to the invention can perform various functions depending on the structure of the switching element. For example, a conductive substrate can serve as the first electrode. Similarly, the substrate can be a layer of a diode.

[0083] Suitable substrates are known to those skilled in the art. Suitable substrates are: - Elemental semiconductors such as Si, Ge, C (diamond, graphite, graphene, fullerene), α-Sn, B, Se and Te; - Compound semiconductors, preferably - Group III-V semiconductors, especially GaAs, GaP, InP, InSb, InAs, GaSb, GaN, TaN, TiN, MoN, WN, AlN, InN, Al x Ga 1-x As and In x Ga1-x Ni, - II-VI group semiconductors, especially ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, Hg (1-x) Cd (x) Te, BeSe, BeTe x and HgS; - III-VI group semiconductors, especially GaS, GaSe, GaTe, InS, InSe x and InTe, - I-III-VI group semiconductors, especially CuInSe2, CuInGaSe2, CuInS2 and CuInGaS2, - IV-IV group semiconductors, especially SiC and SiGe, - IV-VI group semiconductors, especially SeTe; - Organic semiconductors, especially polythiophene, tetracene, pentacene, phthalocyanine, PTCDA, MePTCDI, quinacridone, acridone, indanthrone, flaranthrone, perinone, AlQ3, and mixed systems, especially PEDOT:PSS and polyvinylcarbazole / TLNQ composites; - Metals, especially Ta, Ti, Co, Mo, Pt, Ru, Au, Ag, Cu, Al, W and Mg; - Conductive oxidizing materials, especially indium tin oxide (ITO), indium gallium oxide (IGO), InGa-α-ZnO (IGZO), aluminum-doped zinc oxide (AZO), tin-doped zinc oxide (TZO), fluorine-doped tin oxide (FTO) and antimony tin oxide are selected from.

[0084] The molecular layer may also be optionally bonded to a thin (preferably 0.5 to 5 nm thick) oxidizing or fluorinating intermediate layer, such as TiO2, Al2O3, HfO2, SiO2 or LiF, positioned on the substrate.

[0085] The counter electrode or the second electrode consists of a conductive or semiconductive material or a combination (laminate) of a plurality of these materials. Examples include the materials mentioned as substrate materials. Preferably, Hg, In, Ga, InGa, Ag, Au, Cr, Pt, PdAu, Pb, Al, Mg, W, Yb, Zn, CNT (carbon nanotube), graphene and conductive polymers (such as PEDOT:PSS) are mentioned.

[0086] The manufacture and structuring of the electrodes are carried out using processes known to those skilled in the art. The fabrication and electrical characterization of the switching element comprising a molecular layer obtained from one or more compounds represented by formula I are carried out according to the procedures described in WO2016 / 110301A1 and WO2018 / 007337A2.

[0087] Example Synthesis Example 1: 3-[4-(1-Adamantyl)-2,3-difluoro-phenoxy]propyl-phosphonic acid Step 1: 4-(1-Adamantyl)-2,3-difluoro-phenol

Number

[0088] Step 2: 1-[4-(3-Diethoxyphosphorylpropoxy)-2,3-difluoro-phenyl]adamantane

Number

[0089] A solution of 4-(1-adamantyl)-2,3-difluoro-phenol (5.72 g, 21.65 mmol) and diethyl (3-bromopropyl)phosphonate (6.2 g, 22.73 mmol) in methyl ethyl ketone (73 mL) was treated with potassium carbonate (11.97 g, 86.6 mmol), and the mixture was heated at reflux overnight, cooled to 40 °C, filtered, and the solid was washed with acetone. The filtrate was concentrated under vacuum until dry to give a colorless oil, which was purified on silica with ethyl acetate / DCM (0-50%) to give 1-[4-(3-diethoxyphosphorylpropoxy)-2,3-difluoro-phenyl]adamantane as a colorless solid. 1 H NMR (400 MHz, CHCl3-d) δ ppm 1.32 (6 H, t, J=7.0 Hz), 1.77 (6 H, m), 1.90-2.14 (13 H, m), 4.06-4.16 (6 H, m), 6.62-6.67 (1 H, m), 6.84 (1 H, td, J=8.4 Hz, 2.4 Hz). 19 F NMR (400 MHz, CHCl3-d) δ ppm -159.52 (1 F, d, J=17.7 Hz), -136.00 (1 F, d, J=17.7 Hz). 31 P NMR (400 MHz, CHCl3-d) δ ppm 31.55

[0090] Step 3: 3-[4-(1-adamantyl)-2,3-difluoro-phenoxy]propylphosphonic acid

Number

[0091] A solution of 1-[4-(3-diethoxyphosphorylpropoxy)-2,3-difluoro-phenyl]adamantane (5.53 g, 12.50 mmol) in dichloromethane (83.0 mL) was added dropwise with trimethylsilyl bromide (19.1 g, 125.0 mmol) over 10 minutes, and the solution was stirred overnight at room temperature. The reaction mixture was concentrated to dryness, dichloromethane (110 mL) and methanol (55 mL) were added, and the dichloromethane was slowly removed. When further distillation of the solvent ceased, the remaining solution was stirred at room temperature and a solid precipitated upon cooling. The mixture was stirred at 0 - 5 °C for 1 hour, then the solid was collected by filtration and washed with methanol to give 3-[4-(1-adamantyl)-2,3-difluoro-phenoxy]propylphosphonic acid as a white solid. 1 H NMR (400 MHz, THF-d) δ ppm 1.78 - 1.86 (8 H, m), 2.03 - 2.10 (11 H, m), 4.10 (2 H, t, J = 6.4 Hz), 6.77 - 6.82 (1 H, m), 6.87 - 6.92 (1 H, m). 19 F NMR (400 MHz, THF-d) δ ppm -162.95 (1 F, d, J = 17.7 Hz), -139.85 (1 F, d, J = 17.7 Hz). 31 P NMR (400 MHz, THF-d) δ ppm 29.69. ES (-ve) MS: m / z = 385.1382, 100% [M - H] - , C 19 H 24 F2O4P - requires 385.1380.

[0092] Synthesis Example 2 Step 1: 11-[4-(1-adamantyl)-2,3-difluoro-phenoxy]undecan-1-ol

Number

[0093] To a solution of 4-(1-adamantyl)-2,3-difluoro-phenol (7.0 g, 26.5 mmol) and 11-bromoundecanol (7.0 g, 27.8 mmol) in methyl ethyl ketone (88 mL) was added potassium carbonate (14.6 g, 105.9 mmol) portionwise, and the mixture was heated at reflux overnight. The solid was washed with acetone, and the filtrate was concentrated under vacuum to dryness at 40 °C to give a white solid (11.8 g). Recrystallization from heptane yields 11-[4-(1-adamantyl)-2,3-difluoro-phenoxy]undecan-1-ol as a white solid.

[0094] 1 H NMR (400 MHz, CHCl3-d) δ ppm 1.25 - 1.40 (12 H, m), 1.42 - 1.49 (4 H, m), 1.58 (2 H, m), 1.78 - 1.84 (8 H, m), 2.01 (6 H, d, J = 2.3 Hz), 2.09 (3 H, br s), 3.65 (2 H, t, J = 6.5 Hz), 4.01 (2 H, t, J = 6.5 Hz), 6.65 (1 H, m), 6.85 (1 H, td, J = 8.7 Hz, 2.4 Hz). 13 C NMR (400 MHz, CHCl3-d) δ ppm 25.68, 25.84, 28.80, 29.14, 29.27, 29.37, 29.45, 29.47, 29.53, 32.66, 36.21 (dd, J = 3.3 Hz, 1.8 Hz), 36.74, 41.28 (d, J = 3.7 Hz), 63.01, 69.66, 108.57 (d, J = 2.2 Hz), 119.58 (dd, J = 7.3 Hz, 4.4 Hz), 131.24 (dd, J = 8.4, 1.8 Hz), 142.0 (dd, J = 246 Hz, 15.8 Hz), 146.38 (dd, J = 8.1 Hz, 2.9 Hz), 151.1 (dd, J = 250 Hz, 10.3 Hz). 19 19F NMR (400 MHz, CHCl3-d) δ ppm -159.38 (1 F, d, J = 17.7 Hz), -136.25 (1 F, d, J = 17.7 Hz).

[0095] Step 2: 1-[4-(11-Bromoundecyloxy)-2,3-difluoro-phenyl]adamantane [Number]

[0096] 11-[4-(1-Adamantyl)-2,3-difluoro-phenoxy]undecan-1-ol (10.5 g, 24.16 mmol) and triphenylphosphine (8.81 g, 26.58 mmol) in dichloromethane (105 mL) are cooled to 2 °C. Carbon tetrabromide (8.81 g, 26.58 mmol) is added portionwise over 10 minutes, and the reaction is stirred overnight at room temperature. Further, triphenylphosphine (1.90 g) and carbon tetrabromide (2.4 g) are added successively in one portion. The reaction mixture is concentrated until dry, heptane (250 mL) is added, and it is stirred at 50 °C for 45 minutes. The solid is collected by filtration and washed with hot heptane. The filtrates are combined and concentrated under vacuum at 50 °C to give a solid. Heptane (140 mL) is added and filtered through a pad of silica, and the pad is washed with hot heptane (700 mL). The filtrate is concentrated until dry to give a solid. This is recrystallized from heptane to give 1-[4-(11-bromoundecyloxy)-2,3-difluoro-phenyl]adamantane as an off-white solid.

[0097] 11H NMR (400 MHz, CDCl₃) δ ppm 1.25 - 1.38 (10 H, m), 1.39 - 1.51 (4 H, m), 1.76 - 1.91 (10 H, m), 2.01 (6 H, d, J = 2.5 Hz), 2.09 (3 H, br. s.), 3.42 (2 H, t, J = 6.9 Hz), 4.01 (2 H, t, J = 6.5 Hz), 6.65 (1 H, m), 6.85 (1 H, td, J = 8.7, 2.5 Hz). 13 ¹³C NMR (400 MHz, CDCl₃) δ ppm 25.84, 28.13, 28.72, 28.81, 29.15, 29.28, 29.37, 29.40, 29.44, 32.80, 33.99, 36.22 (dd, J = 2.9 Hz, 1.5 Hz), 36.76, 41.29 (d, J = 2.9 Hz), 69.66, 108.58 (m), 119.58 (dd, J = 7.3, 4.4 Hz), 131.24 (dd, J = 8.8, 2.2 Hz), 142.00 (dd, J = 245.8 Hz, 16.1 Hz), 146.39 (dd, J = 8.4, 2.6 Hz), 151.09 (dd, J = 249.4 Hz, 11.0 Hz). 19 ¹⁹F NMR (400 MHz, CDCl₃) δ ppm -159.76 (d, J = 17.71 Hz), -136.24 (d, J = 17.71 Hz)

[0098] Step 3: 11-[4-(1-Adamantyl)-2,3-difluoro-phenoxy]undecylphosphonic acid

Number

[0099] 1-[4-(11-Bromoundecyloxy)-2,3-difluoro-phenyl]adamantane (8.2 g, 16.5 mmol) and triethyl phosphite (8.21 g, 49.45 mmol) are heated at 135 °C for 70 h under nitrogen. A further portion of triethyl phosphite (1.4 g, 8.3 mmol) is added, and the reaction is heated at 145 °C overnight. Another 1.4 g (8.3 mmol) of triethyl phosphite is added, and the reaction mixture is heated for 24 h. The reaction is evaporated under reduced pressure, and the crude 1-[4-(11-diethoxyphosphorylundecyloxy)-2,3-difluoro-phenyl]adamantane is dissolved in dichloromethane (137 mL), trimethylsilyl bromide (75.7 g, 494 mmol) is added dropwise over 15 min, and the solution is stirred overnight. The reaction is concentrated in vacuo until dry. Dichloromethane (180 mL) and methanol (90 mL) are added to the solid, and the dichloromethane is slowly removed until no further solvent distills. The solution is cooled to -5 °C and stirred for 30 min. The precipitate is filtered off, washed with cold methanol, and dried to give 11-[4-(1-adamantyl)-2,3-difluoro-phenoxy]undecylphosphonic acid as a white solid, which is recrystallized from THF / heptane.

[0100] 1 H NMR (400 MHz, THF-d8) δ ppm 1.25 - 1.43 (12 H, m), 1.43 - 1.52 (2 H, m), 1.52 - 1.65 (4 H, m), 1.75 - 1.85 (8 H, m), 1.97 - 2.12 (9 H, m), 4.01 (2 H, t, J=6.5 Hz), 6.73 - 6.81 (1 H, m), 6.89 (1 H, td, J=8.8 Hz, 2.3 Hz). 19 F NMR (400 MHz, THF-d8) δ ppm -161.2 (1 F, d, J=17.7 Hz), -138.1 (1 F, d, J=17.7 Hz). 311P NMR (400 MHz, THF-d8) δ ppm 32.5. ES (-ve) MS: m / z = 497.2623, 100% [M-H] - , C 27 H 40 F2O4P - requires 497.2632.

[0101] Synthesis Example 3 Step 1: 1-Adamantylmethyl methanesulfonate

Count

[0102] 1-Adamantylmethanol (163 g, 0.98 mol) is dissolved in dichloromethane (1.9 L), and then methanesulfonyl chloride (124 g, 1.08 mol) is added under ice-cooling. Triethylamine (198 g, 1.98 mol) is added dropwise. The reaction mixture is warmed to room temperature and stirred overnight. The mixture is filtered, and the white solid is washed with dichloromethane. The filtrate is stirred with HCl (81 mL diluted to 1 L in 37%) for 30 minutes, then the organic matter is separated and stirred with aq. Na2CO3 (500 mL) overnight. The organic phase is separated, dried over MgSO4, filtered, and the solvent is removed to yield 1-adamantylmethyl methanesulfonate as an off-white solid. 1 1H NMR (400 MHz, CHCl3-d) δ ppm 1.57 (d, J=2.32 Hz, 6 H) 1.62 - 1.68 (m, 3 H) 1.71 - 1.78 (m, 3 H) 2.02 (br. s., 3 H) 3.00 (s, 3 H) 3.78 (s, 2 H)

[0103] Step 2: 1-[(4-Bromo-2,3-difluoro-phenoxy)methyl]adamantane

Count

[0104] 4-Bromo-2,3-difluorophenol (50 g, 240 mmol) is dissolved in dimethylformamide (500 mL). K2CO3 (66 g, 480 mmol) is added, followed by the addition of adamantan-1-ylmethyl methanesulfonate (70 g, 288 mmol), and the reaction mixture is stirred at 120 °C for 36 h. The mixture is poured into water (1 L) and extracted with dichloromethane. The organic layer is washed with brine, dried over MgSO4, filtered, and the solvent is removed. The crude material is filtered through silica with heptane to give 1-[(4-bromo-2,3-difluoro-phenoxy)methyl]adamantane as a colorless solid.

[0105] Step 3: [4-(1-Adamantylmethoxy)-2,3-difluoro-phenyl]boronic acid

Number

[0106] To 1-[(4-bromo-2,3-difluoro-phenoxy)methyl]adamantane (59.3 g, 116 mmol) in THF (600 mL) under nitrogen, n-butyllithium (2.5 M, 76 mL, 183 mmol) is added dropwise at -70 °C within 1 hour. The reaction mixture is stirred at -70 °C for 1 hour, then trimethyl borate (24 mL, 216 mmol) is added, and the reaction mixture is slowly warmed to room temperature and stirred overnight. Water (200 mL) is added, and the mixture is poured into dilute HCl and stirred for 30 minutes. The organic phase is separated, and the aqueous phase is extracted with MTB ether (200 mL). The combined organic layers are washed with brine, dried over MgSO4, filtered, and the solvent is removed. The crude material is suspended in dichloromethane and purified by chromatography on silica with 5% methanol in dichloromethane followed by THF. [4-(1-adamantylmethoxy)-2,3-difluoro-phenyl]boronic acid is obtained as a yellow amorphous solid. 1 H NMR (400 MHz, CHCl3-d) δ ppm 1.67 (d, J=2.08 Hz, 6 H) 1.69 - 1.74 (m, 3 H) 1.75 - 1.81 (m, 3 H) 2.04 (br. s., 3 H) 3.55 (s, 2 H) 6.62 - 6.69 (m, 1 H) 7.18 (ddd, J=9.14, 7.12, 2.32 Hz, 1 H)

[0107] Step 4: 4-(1-Adamantylmethoxy)-2,3-difluorophenol

Number

[0108] [4-(1-Adamantylmethoxy)-2,3-difluoro-phenyl]boronic acid (43 g, 133 mmol) was dissolved in THF (400 mL), then acetic acid (16 mL 280 mmol) in 40 mL of water was added, and the mixture was stirred for 5 minutes. Hydrogen peroxide (30.3 mL 30% solution) was added dropwise over 10 minutes, and the reaction was stirred overnight at room temperature. A bisulfite solution (270 mmol in 600 mL) was added. The mixture was cooled to room temperature, and the organic phase was separated. The aqueous phase was extracted with MTB ether (200 mL), and the combined organics were washed with dilute bisulfite, water and brine, and dried over MgSO4. The solvent was removed, and the crude material was recrystallized from dichloromethane / heptane to give 4-(1-adamantylmethoxy)-2,3-difluorophenol. 1H NMR (400 MHz, CDCl3-d) δ ppm 1.67 (d, J=2.32 Hz, 6 H) 1.68 - 1.74 (m, 3 H) 1.74 - 1.80 (m, 3 H) 2.03 (br. s., 3 H) 3.52 (s, 2 H) 4.76 (br. s., 1 H) 6.50 - 6.80 (m, 2 H).

[0109] Step 5: 1-[[4-(3-bromopropoxy)-2,3-difluoro-phenoxy]methyl]adamantane

Number

[0110] To a solution of 4-(1-adamantylmethoxy)-2,3-difluorophenol (4.00 g, 13.6 mmol) in acetone (50 mL) are added potassium carbonate (2.20 g, 15.9 mmol) and then 1,3-dibromopropane (6.90 mL, 67.9 mmol). The mixture is heated at reflux for 15 h, filtered, and the filtrate is concentrated under reduced pressure. The residue is purified by silica gel chromatography with increasing dichloromethane to give 1-[[4-(3-bromopropoxy)-2,3-difluoro-phenoxy]methyl]adamantane as a pale yellow oil.

[0111] Step 6: 1-[[4-(3-di-tert-butoxyphosphorylpropoxy)-2,3-difluoro-phenoxy]methyl]adamantane

Count

[0112] Sodium hydride (60% suspension in mineral oil; 581 mg, 14.5 mmol) was added portionwise to di-tert-butyl phosphite (2.9 mL, 14.5 mmol) in THF (30 mL), and the mixture was stirred at room temperature for 45 minutes. A solution of 1-[[4-(3-bromopropoxy)-2,3-difluoro-phenoxy]methyl]-adamantane (3.45 g, 8.30 mmol) in THF (30 mL) was added, and the mixture was heated under reflux for 15 hours, cooled, and quenched with water. MTB ether (200 mL) and water (200 mL) were added, and the layers were separated. The aqueous layer was extracted with MTB ether; the organic layers were combined, washed with water, brine, dried (MgSO4), filtered, and concentrated under reduced pressure. Excess di-tert-butyl phosphite was removed via Kugelrohr distillation at 50 °C and 10 mbar, and the crude product was purified by silica gel chromatography using 0% - 100% EtOAc in CH2Cl2 as the eluent. 1-[[4-(3-di-tert-butoxyphosphorylpropoxy)-2,3-difluoro-phenoxy]methyl]adamantane was obtained as a waxy colorless solid.

[0113] Similar to Synthesis Example 1, the following compounds were obtained:

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0114] Usage Example Contact Angle Measurement The preparation of the test chip is carried out by the following steps: 1. Preparation of a solution of the compound to be investigated in THF (c = 1 mmol / l) 2. O2 plasma cleaning / oxidation of an 8x8 mm silicon chip with 30 nm Al (p < 0.3 mbar O2, t = 1 minute, 150 W (W = 50%)) 3. Immersion of the chip in the compound solution of step 1 for 72 hours 4. Drying in a N2 gas stream 5. Baking for 1 hour in a N2 atmosphere (120 °C) 6. Cleaning by rinsing briefly with THF 7. Drying in a N2 gas stream

[0115] The following compounds are investigated:

Table 1

[0116] Comparative Example : For comparison, the contact angles using the following compounds from the state of the art were measured and the contact angles given in the following table were obtained:

Chemical formula

Table 2

[0117] The contact angles of the adamantane derivatives according to the present invention were almost the same for all examples, while the reference compounds tended to have lower contact angles for shorter linker lengths.

[0118] SAMs containing one or more compounds according to the present invention have better process stability because their surface energies are close to the design range of most photoresist formulations. This ensures higher reproducibility of wetting and film formation during the coating process.

[0119] Fabrication of Switching Device The molecular layer is prepared from Synthesis Example 2 (11-[4-(1-adamantyl)-2,3-difluoro-phenoxy]undecylphosphonic acid, PA-11O-Y-Ada), and another molecular layer is prepared for comparison from 11-[2,3-difluoro-4-(4-pentylcyclohexyl)phenoxy]undecylphosphonic acid (page 63 of WO2018 / 007337 A2, Compound Example 19, PA-11O-YC-5) as follows:

[0120] 1) Substrate preparation: The starting material is a 6-inch silicon-on-insulator wafer ("SOI wafer") having a silicon layer with a thickness of 110 nm and an orientation of

[0100] on a silicon oxide layer with a thickness of 200 nm on a slightly boron-doped silicon wafer with a thickness of 525 μm and a resistivity of about 20 Ωcm in the

[0100] orientation.

[0121] The upper silicon layer is highly boron-doped by ion implantation (doping concentration c ~ 5×10 19 cm -3 , resistivity ρ ~ 1.4 mΩ.cm). After doping, the wafer is diced into square parts ("chips") measuring 8 mm × 8 mm. The chips are first cleaned in acetone and subsequently in an ultrasonic bath in isopropanol for 10 minutes in each case.

[0122] 2) Film formation of the phosphonic acid layer The freshly manufactured chips as described above are again purified in an ultrasonic bath for 5 minutes in each case in acetone and isopropanol and subsequently treated with a piranha solution at 70 °C. After rinsing with deionized water, the chips are treated with oxygen plasma (200 W, 7 minutes) to produce a hydroxyl-grouped silicon dioxide layer on the silicon conductor track, hydrophilize the surface, and make it reactive towards phosphonic acid.

[0123] For the formation of the phosphonic acid layer, the chips are dip-coated with a 250 μM solution of the corresponding phosphonic acid in tetrahydrofuran, then heated overnight in an oven at 120 °C, and then washed with ethanol. This process essentially corresponds to the "TBAG" method known from the literature and gives a self-assembled monolayer.

[0124] The breakdown voltage of the molecular layer is determined using a dropping mercury electrode according to the procedure described on pages 72 - 75 of WO2018 / 007337A2. The following values are obtained: PA-11O-Y-Ada: +5.38 ± 0.68 V PA-11O-YC-5: +3.90 ± 0.32 V.

[0125] Surprisingly, it can be seen that the adamantyl derivatives according to the invention give devices with significantly higher breakdown voltages.

[0126] The electrical characterization of the switching device 100 (Figure 1) containing the molecular layer 140 obtained from the compound PA-11O-Y-Ada sandwiched between the TiN first electrode 130 (50 nm thick) on the silicon substrate 110 and the Ti second electrode 150 (10 nm) with the Au contact 160 is made with a nanoprobe (Hitachi High-Tech nanoprobe N-6000SS, probe size about 1 μm) and an Agilent B1500 device analyzer under SEM control. The devices are fabricated starting from the same silicon substrate described above. The fabrication of the test devices follows industry standard procedures. The titanium nitride first electrode 130 is deposited by reactive sputtering (Ti target, in an N2 atmosphere).

[0127] The silicon wafer 110 with a silicon oxide intermediate layer 120 coated with a 50 nm thick layer of TiN deposited by reactive sputtering is activated by ozone / UV treatment (110 W / 300 s) and subsequently immersed for 24 hours in a 1 mM solution of the phosphonic acid PA-11O-Y-Ada (vide supra) in tetrahydrofuran (THF). The chip is removed from the immersion bath, blown dry with nitrogen, and annealed at 120 °C for 60 minutes under nitrogen. The chip is then rinsed with THF on a spin coater and subsequently annealed again at 120 °C for 5 minutes under nitrogen. The titanium top electrode 150 and the Au contact 160 are applied by sputtering using standard processes.

[0128] The results of the electrical characterization of the device 100 are shown in Figure 2. The A forward scan 210 starts at 0 V and the voltage is increased up to +3.5 V; the backward scan 220 then returns to 0 V, further proceeds up to a maximum of -3.5 V, and returns to 0 V. The scan speed is 300 mV / s. The resulting current is measured and the results are shown in Figure 2. The device advantageously has a large memory window.

Claims

1. A compound represented by formula I, wherein D 1 -Z D -(A 1 -Z 1 ) r -B 1 -(Z 2 -A 2 ) s -Sp-G (I) represents, where the group may be oriented in both directions, D 1 represents a diamondoid radical, wherein radical D 1 is selected from the group consisting of adamantyl, diamantyl and triamantyl, in each of which one or more H atoms may be replaced by F, or in each case may be replaced by an optionally fluorinated alkyl, alkenyl or alkoxy having up to 12 C atoms, A 1 and A 2 represents, in each occurrence, an aromatic, heteroaromatic, alicyclic or heteroaliphatic ring having from 4 to 25 ring atoms, which may also contain a condensed ring and may be mono- or polysubstituted by Y, either identically or differently. Y is, in each occurrence, the same or different, F, Cl, CN, SCN, SF 5 or a straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having from 1 to 12 carbon atoms, optionally fluorinated in each case, and B 1 is 【Chemical 1】 [Chemical Formula 2] n1, n2, n3, n4 are, identically or differently, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, L 1 ~L 5 are, independently of each other, F, Cl, Br, I, CN, SF 5 , CF 3 or OCF 3 , where L 3 may alternatively also represent H, Z 1 and Z 2 each occurrence, independently of one another, is a single bond, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH 2 O-, -OCH 2 -, -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -(CH 2 ) n1 -, -(CF 2 ) n2 -, -CF 2 -CH 2 -, -CH 2 -CF 2 -, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CH 2 ) n3 O-, -O(CH 2 ) n4 -, -C≡C-, -O-, -S-, -CH=N-, -N=CH-, -N=N-, -N=N(O)-, -N(O)=N- or -N=C-C=N-, and the group Sp represents Sp'-X' such that the radical G-Sp- represents G-Sp'-X', where r and s independently of one another represent 0, 1, 2 or 3, Sp' represents a linear or branched alkylene having 1 to 20 carbon atoms, which is optionally mono- or poly-substituted by F, Cl, Br, I or CN, and wherein, in addition, one or more non-adjacent CH 2 groups are, independently of one another, -O-, -S-, -NH-, -NR 0 -,-SiR 00 R 000 -, -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -NR 0 -CO-O-, -O-CO-NR 0 -,-NR 0 -CO-NR 0 - may each be replaced by -CH=CH- or -C≡C-, X' represents -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 00 -, -NR 00 -CO-, -NR 00 -CO-NR 00 -, -OCH 2 -, -CH 2 O-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CF 2 CH 2 -, -CH 2 CF 2 -, -CF 2 CF 2 -, -CH=N-, -N=CH-, -N=N-, -CH=CR 00 -, -CY x =CY x‘ -, -C≡C-, -CH=CH-COO-, -OCO-CH=CH- or a single bond, and R 0 、R 00 and R 000 each independently represents H or alkyl having 1 to 12 C atoms, and Y x and Y x‘ each independently represents H, F, Cl or CN, Z D has the meaning of Z 1 and Z 2 and has one of the meanings of Sp, G represents -OH, -CH(CH 2 OH) 2 、-C(CH 2 OH) 3 、-SH, -SO 2 OH, -OP(O)(OH) 2 、-PO(OH) 2 、-C(OH)(PO(OH) 2 ) 2 、-COOH, -B(OH) 2 、-Si(OR x ) 3 or -SiCl 3 、-SO 2 OR V 、-OP(O)(OR V ) 2 、-PO(OR V ) 2 、-C(OH)(PO(OR V ) 2 ) 2 、-COOR V 、-Si(OR V ) 3 and represents R V represents a linear or branched alkyl having 1 to 20 carbon atoms, R x represents a linear or branched alkyl having 1 to 6 carbon atoms, and where r + s ≦ 4, said compound. However, when Sp represents a single bond, Z 2 is neither O, S, CH 2 nor CF 2 nor anything else.

2. a) 1,4-phenylene, where one or two CH groups may be replaced by N, and where, in addition, one or more H atoms may be replaced by Y, A 1 and A 2 are, in each occurrence, the same or different and are from the following group: c) a group consisting of 1,3-dioxolane-2,4-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, 1,4-bicyclo[2.2.2]octanediy, piperidine-1,5-diyl and thiophene-2,5-diyl, where one or more H atoms may be replaced by Y, b) a group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, wherein one or more non-adjacent CH 2 may be replaced by -O- and / or -S-, and wherein, in addition, one or more H atoms may be replaced by Y, and where Y has the meaning given in claim 1, a compound according to claim 1, selected from

3. represents, B 1 is 【Chemical 3】 a compound according to claim 1 or 2. L 1 and L 2 each, if present, independently represents Cl or F, where at least one of radical L 1 and L 2 represents F, and L 3 represents F

4. a compound according to any one of claims 1 to 3. G is -P(O)(OH) 2 , -OP(O)(OH) 2 or -C(OH)(PO(OH) 2 ) 2 and represents

5. a compound according to any one of claims 1 to 4 Z D is a single bond, -C≡C-, -C(O)O-, -OC(O)-, -OCH 2 -, -CH 2 O-, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 -, or -CH 2 CH 2 CH 2 CH 2 - represents,

6. A process for the manufacture of a switching element, comprising at least the following steps: a) manufacture of a first electrode having a surface, b) deposition of a molecular layer comprising a compound according to any one of claims 1 to 5 on the surface of the first electrode, c) application of a second electrode said process.

7. A process according to claim 6, wherein the first electrode comprises a material selected from the elemental semiconductors Si, Ge, C, Sn and Se, the compound semiconductors GaAs, InAs, InP, GaSb, TaN, TiN, MoN, WN and GaN, CdSe and ZnS, the metals Au, Ag, Cu, Al, W, Ta, Ti, Co, Mo, Pt, Ru and Mg and the conductive oxide materials ITO, IGO, IGZO, AZO and FTO.

8. A switching element comprising a molecular layer sandwiched between a first electrode and a second electrode, obtainable by the process according to claim 6.

9. A switching element according to claim 8, wherein the molecular layer is a self-assembled monolayer.

10. ​ ​ A memristor device comprising the switching element according to claim 8 or 9.

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