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EP-4741469-A1 - LIQUID CRYSTAL MEDIUM AND ELECTRONIC COMPONENT

EP4741469A1EP 4741469 A1EP4741469 A1EP 4741469A1EP-4741469-A1

Abstract

The present invention relates to a liquid crystal medium and liquid crystal material comprising a) one or more compounds of formula I and one or more compounds of the formula T: in which the occurring groups and parameters have the meanings defined in claim 1, and to an electronic component comprising said LC medium, operable in the visible (VIS), infrared (IR) or microwave region of the electromagnetic spectrum. The invention further relates to the use of said LC medium in the IR, VIS or microwave region and to devices comprising said electronic component.

Inventors

  • SAITO, IZUMI
  • MEYER, ELISABETH

Assignees

  • Merck Patent GmbH

Dates

Publication Date
20260513
Application Date
20251107

Claims (18)

  1. A liquid crystal medium comprising a) one or more compounds of formula I in which R 11 and R 12 , identically or differently, denote H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH 2 -groups may be replaced by and in which one or more H atoms may be replaced by fluorine, L 11 , L 12 , L 13 identically or differently, denote H, CH 3 , Cl or F, A 11 denotes phenylene-1,4-diyl, in which one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH 3 , CHF 2 , CH 2 F, CF 3 , OCH 3 , OCHF 2 or OCF 3 , or cyclohexane-1,4-diyl or cyclohexene-1,4-diyl, in each of which one or two non-adjacent CH 2 groups may be replaced, independently of one another, by O and/or S and one or more H atoms may be replaced by F, or bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]-octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, in which one or more H atoms may be replaced by F, A 12 denotes phenylene-1,4-diyl, in which one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH 3 , CHF 2 , CH 2 F, CF 3 , OCH 3 , OCHF 2 or OCF 3 , or cyclohexane-1,4-diyl or cyclohexene-1,4-diyl, in each of which one or two non-adjacent CH 2 groups may be replaced, independently of one another, by O and/or S and one or more H atoms may be replaced by F, Z 1 denotes a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF- or -CH=CHCH 2 O-, n is 0 or 1; and b) one or more compounds of the formula T, in which R T1 and R T2 , identically or differently, denote halogen, CN, NCS, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl or alkenyloxy having 3 to 15 C atoms, where one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -OCF 2 -, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, R T3 denotes F, CN, straight chain alkyl or alkoxy having 1 to 5 C atoms, straight chain alkenyl or alkenyloxy having 2 to 5 C atoms or branched alkyl, alkoxy, alkenyl or alkenyloxy having 3 to 5 C atoms, where a CH 2 groups in these radicals may be replaced by and in which one or more H atoms may be replaced by halogen, A 0 , A 1 , and A 2 , each, independently of one another, denote phenylene-1,4-diyl, in which one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH 3 , CHF 2 , CH 2 F, CF 3 , OCH 3 , OCHF 2 or OCF 3 , cyclohexane-1,4-diyl, in which one or two non-adjacent CH 2 groups may be replaced, independently of one another, by O and/or S and one or more H atoms may be replaced by F, cyclohexene-1,4-diyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl; Z 1 and Z 2 , each, independently of one another, denote -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 - , -CO-O-, -O-CO-, -C 2 H 4 -, -C 2 F 4 , -CF 2 CH 2 -, -CH 2 CF 2 -, -CFHCFH-, - CFHCH 2 -, -CH 2 CFH-, -CF 2 CFH-, -CFHCF 2 -, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C≡C- or a single bond; n denotes 0, 1, 2 or 3; and m denotes 0, 1, 2 or 3.
  2. The liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae S1, S2 and S3 in which R S1 and R S2 , on each occurrence, identically or differently, denote H or straight-chain alkyl having from 1 to 25 carbon atoms or branched alkyl having from 3 to 25 carbon atoms, which are unsubstituted or monosubstituted by CN or CF 3 or at least monosubstituted by halogen and in which one or more CH 2 groups may each, independently of one another, be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C- in such a way that O and/or S atoms are not linked directly to one another, or halogen, aryl, heteroaryl, alkylaryl or arylalkyl having from 6, 5, 7, or 7 to 25 carbon atoms, respectively, each of which is unsubstituted or monosubstituted or polysubstituted by alkyl having from 1 to 6 C atoms or by halogen, s is 0, 1 or 2, t is 0, 1, 2 or 3, q is 1, 2, 3 or 4, G denotes a hydrocarbon radical having from 1 to 60 carbon atoms, that can be straight chain or branched or cyclic, and which is unsubstituted or monosubstituted by CN or CF 3 or at least monosubstituted by halogen and in which one or more CH 2 groups may each, independently of one another, be R 0 replaced by -O-, -S-, -NR 0 -, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C- in such a way that O or S atoms are not linked directly to one another, denotes H or alkyl having 1 to 6 C atoms, R 2 denotes H, -O•, -OH, straight chain alkyl or alkoxy having 1 to 12 C atoms or branched or cyclic alkyl having 3 to 25 C atoms or arylalkoxy having 7 to 25 C atoms, R 21 and R 22 identically or differently, denote a straight-chain alkyl having from 1 to 12 carbon atoms or branched alkyl having from 3 to 12 carbon atoms, or R 21 and R 22 , together with the carbon atom to which they are attached, form a cycloalkyl group having from 5 to 12 carbon atoms, R 23 and R 21 identically or differently, denote a straight-chain alkyl having from 1 to 12 carbon atoms or branched alkyl having from 3 to 12 carbon atoms, or R 23 and R 24 , together with the carbon atom to which they are attached, form a cycloalkyl group having from 5 to 12 carbon atoms, Z 2 on each occurrence, identically or differently, denotes -O-, -C(O)O-, -OC(O)- or a single bond, R ST denotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH 2 -groups may be replaced by and in which one or more H atoms may be replaced by fluorine, Z ST each, independently of one another, denote -CO-O- , -O-CO-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -CH 2 -, -CH 2 CH 2 , -(CH 2 ) 4 -, -CH=CH-CH 2 O-, -C 2 F 4 -, -CH 2 CF 2 -, -CF 2 CH 2 - , -CF=CF- , -CH=CF- , -CF=CH- , -CH=CH- , -C≡C- or a single bond, on each occurrence, identically or differently, denotes cyclohexane-1,4-diyl, cyclohexene-1,4-diyl, pyrane-2,5-diyl or 1,3-dioxane-2-5-diyl, in which one or more H atoms may be replaced by F, p is 0, 1 or 2.
  3. The liquid crystal medium according to claim 1 or 2, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae S2-1 and S2-2 in which G denotes a divalent aliphatic radical having 1 to 20 C atoms or a cycloaliphatic radical having 3 to 20 C atoms.
  4. The liquid crystal medium according to one or more of claims 1 to 3, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae 1-1 to I-3: in which R 11 , R 12 , Z 1 , L 11 , L 12 and L 13 have the meanings given in claim 1.
  5. The liquid crystal medium according to one or more of claims 1 to 4, wherein the medium comprises one or more compounds of the formulae T-1 to T-6 in which R T1 , R T2 and R T3 have the meanings indicated in claim 1, L denotes halogen, CN, CH 3 , CHF 2 , CH 2 F, CF 3 , OCH 3 , OCHF 2 or OCF 3 , and r, s and t independently are 0, 1, 2, 3, or 4.
  6. The liquid crystal medium according to one or more of claims 1 to 5, wherein the medium comprises one or more compounds of the formula S1-1 in which R S1 denotes H, F or Cl, and R 21 and R 22 , identically or differently, denote H or straight-chain or branched alkyl having from 1 to 12 carbon atoms, in which one or more CH 2 groups may each, independently of one another, be replaced by -O-, -CO-O-, -O-CO-, -CH=CH- or -C≡C- in such a way that O atoms are not linked directly to one another, or aryl, or arylalkyl having from 6 to 25 carbon atoms.
  7. The liquid crystal medium according to one or more of claims 1 to 6, wherein the medium comprises one or more compounds selected from the group consisting of the formulae II and III: in which R 2 and R 3 denote a straight-chain or branched alkyl or alkoxy radical that is unsubstituted or halogenated and has 1 to 15 C atoms, where one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, identically or differently, denote L 21 , L 22 , L 31 and L 32 identically or differently, denote H or F, Y 2 and Y 3 identically or differently, denote H or CH 3 , X 2 and X 3 identically or differently, denote halogen, halogenated alkyl or alkoxy with 1 to 3 C-atoms or halogenated alkenyl or alkenyloxy with 2 or 3 C-atoms, Z 3 denotes -CH 2 CH 2 -, -CF 2 CF 2 -, -COO-, trans- -CH=CH-, trans-CF=CF-, - CH 2 O- or a single bond, I, m, n and o are, independently of each other, 0 or 1.
  8. The medium according to one or more of claims 1 to 7, wherein the medium comprises one or more compounds of the formula IV in which R 41 denotes a straight chain alkyl radical having 1 to 12 C atoms or a branched or cyclic alkyl radical having 3 to 12 C atoms, or a straight chain alkenyl radical having 2 to 12 C atoms or a branched alkenyl radical having 3 to 12 C atoms or a cyclic alkenyl radical having 5 to 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine, R 42 denotes a straight chain alkyl or alkoxy radical having 1 to 12 C atoms or a branched or cyclic alkyl or alkoxy radical having 3 to 12 C atoms, or a straight chain alkenyl radical having 2 to 12 C atoms or a branched alkenyl radical having 3 to 12 C atoms or a cyclic alkenyl radical having 5 to 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine.
  9. The medium according to one or more of claims 1 to 8, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae IVa and IVb in which R 41 and R 42 , independently of one another, have the meanings defined in claim 8, and or Z 4 denotes a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -C 4 H 8 -, or -CF=CF-.
  10. An electronic component comprising a first substrate and a second substrate facing each other, a liquid crystal medium sandwiched between said first and second substrates, an electrode provided on each substrate or two electrodes provided on only one of the substrates for supplying an electric potential across said liquid crystal medium to drive liquid crystals in a predetermined configuration, characterised in that said liquid crystal medium comprises the liquid crystal medium according to one or more of claims 1 to 9.
  11. The electronic component according to claim 10, wherein the liquid crystal medium in the component is arranged as a tunable dielectric configured for use in high-frequency technology.
  12. The electronic component according to claim 10 or 11, wherein the component is a liquid-crystal based antenna element, a phase shifter, a tunable filter, a tunable metamaterial structure, a matching network or a varactor.
  13. A microwave antenna array, characterised in that it comprises one or more components according to one or more of claims 10 to 12.
  14. The component according to claim 10, wherein the component is an optical component operable in the visible or infrared range of the electromagnetic spectrum.
  15. The component according to claim 14, wherein the component is a transmissive spatial light modulator.
  16. The component according to claim 14, wherein the component is a reflective spatial light modulator (100) configured to modulate the phase of an incident optical signal propagating at least partially in a first dimension, wherein the first substrate is a transparent glass layer (110) having a first, transparent electrode (120), and wherein the second substrate is a CMOS silicon backplane (160), the component further comprising a mirror (150) disposed between the second substrate and the liquid crystal medium (140), wherein the mirror is divided into a two-dimensional array of individually addressable pixels arranged and configured as second electrodes (150) , each pixel being individually drivable by a voltage signal to provide a local phase change to at least one polarization component of an optical signal.
  17. An optical device comprising - an RGB light source, and - the component according to one of claims 14 to 16, arranged and configured to modulate the phase of an incident optical signal from said RGB light source when the optical device is in operation.
  18. A method of spatially modulating light, the method comprising, i) providing an optical component comprising first and second substrates facing each other and each having a surface, the first substrate comprising at least one first electrode, the second substrate comprising at least one second electrode, the component further comprising a liquid crystal layer sandwiched between the first and second substrates wherein the liquid crystal comprises the liquid crystal medium according to one or more of claims 1 to 9; ii) providing an RGB light source; ii) receiving incident light from said RGB light source at a surface of said optical component; iii) applying a predetermined voltage to each of the individual electrodes formed on the first substrate in order to modulate a refractive index of the liquid crystal layer.

Description

The invention relates to a liquid crystal (LC) medium and to an electronic component comprising said LC medium, operable in the visible (VIS), infrared (IR) or microwave region of the electromagnetic spectrum. The invention further relates to the use of said LC medium in the IR, VIS or microwave region and to devices comprising said electronic component. Liquid-crystalline media have been used for many years in electro-optical displays (liquid crystal displays: LCDs) in order to display information by amplitude modulation of polarised light in the visible region and are widely used in displays for TV, monitor or portable devices such as tablet PC, mobile phones etc. Nematic liquid crystals have also been proposed for phase modulation of light: The article McManamon PF, Dorschner TA, Corkum DL, Friedman LJ, Hobbs DS, Holz M, Liberman S, Nguyen HQ, Resler DP, Sharp RC, Watson EA. Optical phased array technology. Proc IEEE. 1996;84:268-298. doi:10.1109/5.482231 describes liquid crystal based optical phased arrays for various types of sensor applications; the article Scott R. Davis, George Farca, Scott D. Rommel, Seth Johnson, Michael H. Anderson, "Liquid crystal waveguides: new devices enabled by >1000 waves of optical phase control," Proc. SPIE 7618, Emerging Liquid Crystal Technologies V, 76180E (12 February 2010); doi: 10.1117/12.851788 describes refractive beam steering using a waveguide structure. Liquid crystal on silicon (LCoS) is a miniaturized reflective active-matrix liquid-crystal display or "micro display" using a liquid crystal layer on top of a silicon backplane. It is also referred to as a spatial light modulator (SLM). The silicon backplane is an array of pixels, each of which has a mirrored surface which at the same time acts as electrical conductor. Each pixel comprises a stationary mirror covered by an active liquid-crystal layer having a twisted nematic alignment which can be switched into homeotropic alignment by application of a voltage. LCoS micro displays are small, with a diagonal of typically less than 1.0 inch, but enable high resolutions from 1/4 VGA (78 thousand pixels) to UXGA+ (over 2 million pixels). Owing to the small pixel size, LCoS displays also have a very small cell thickness, which is typically about 1 micron. Low cell thickness may also be required when a device operates in reflection mode so light will travel through the LC layer twice. The liquid-crystalline phases used in these displays therefore have to have, in particular, high values for the optical anisotropy Δn, in contrast to conventional reflective-type LC displays, which usually require LC phases of low Δn. Small cell thicknesses are preferably used, in particular, for applications which require a short response time since the response time drops proportionally, often quadratically, with the cell thickness. Liquid-crystalline compounds with high birefringence frequently have an intrinsic smectic phase or induce the formation of a smectic phase when mixed with other liquid-crystalline compounds, which has an adverse effect on the low-temperature stability of the displays. LCoS was initially developed for projection televisions but is now also used for wavelength selective switching, structured illumination, near-eye displays and optical pulse shaping. A computer-generated hologram may be encoded on a spatial light modulator arranged to modulate the amplitude and/or phase of incident light, which forms part of a holographic projector as described in WO2020/015933 A1. Such projectors have found application in head-up displays (HUD) and head-mounted displays (HMD) including near-eye devices. Another application using liquid crystal based devices is light detection and ranging (Lidar) - a method for measuring distances by illuminating a target with laser light and measuring the reflection with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3-D representations of the target. In WO2019/24052 A1, a holographic LIDAR system is proposed that uses for example an LCoS SLM. One of the most important features for a phase-only LCoS device is its use of optically non-linear liquid crystal materials that are sensitive to the working temperature. While the main focus of LCoS devices in the past was on optical intensity modulation, which is little affected by temperature variation, for phase-only LCoS devices optical phase modulation of the incident light is an essential performance parameter and it can easily be affected by a small change of working temperature, resulting in a significant change in the outcome of corresponding optical diffractions. Another key challenge for the development of next generation LCoS devices is the creation of a high-speed multi-level phase modulation. Nematic LCoS devices have demonstrated the benefits of the multi-level phase modulation but are limited by the slow response time of the nematic LC. This is especially the case in telecommunication applic