Device for regulating the passage of energy

Abstract

The present application relates to a device for regulating the passage of light through a light-transmitting area which comprises a switching layer comprising a liquid-crystalline medium comprising at least one dichroic dye, where the parameters degree of light transmission and degree of anisotropy of the device are selected in a certain manner.

Claims

1. A device for regulating the passage of light through a light-transmitting area, said device comprising: one or more glass layers and at least one switching layer which comprises a liquid-crystalline medium comprising at least one dichroic dye, wherein said switching layer has a bright state .sub.v bright and a dark state .sub.v dark, and wherein said switching layer has a degree of anisotropy R of at least 0.65 and a degree of light transmission in the bright state .sub.v bright in accordance with Standard EN410 of 40% to 90%, wherein said device is a component of a window, wherein said switching layer comprises three or more different dichroic dyes, and wherein the liquid-crystalline medium has a clearing point in the temperature range from 70 C. to 170 C.

2. The device according to claim 1, further comprising one or more alignment layers which are arranged directly adjacent to the switching layer.

3. The device according to claim 1, further comprising precisely two alignment layers, one of said alignment layers which is adjacent to one side of the switching layer and the other of said alignment layers is adjacent to the opposite side of the switching layer, and where the two alignment layers cause a parallel or 90-rotated preferential direction of the molecules of the liquid-crystalline medium on both sides of the switching layer.

4. The device according to claim 1, wherein homogeneous alignment of the molecules of the liquid-crystalline medium is present in the voltage-free state, where the molecules are aligned parallel to one another on both sides of the switching layer.

5. The device according to claim 1, further comprising means for the alignment of the molecules of the liquid-crystalline medium of the switching layer by electrical voltage.

6. The device according to claim 1, further comprising a light-guide system which conducts light from the switching layer to a unit which converts light energy into electrical energy or heat energy.

7. The device according to claim 1, further comprising an element for the conversion of light energy into electrical energy which is electrically connected to said device.

8. The device according to claim 1, wherein said one or more glass layers have an antireflection design.

9. The device according to claim 1, wherein said device comprises precisely one switching layer.

10. The device according to claim 1, wherein at least one of said dichroic dyes is luminescent.

11. The device according to claim 1, wherein at least one of the dichroic dyes is an azo compound, an anthraquinone, a methine compound, an azomethine compound, a merocyanine compound, an naphthoquinone, a tetrazine, a perylene, a terrylene, a quaterrylenes, a higher rylene or a pyrromethene.

12. The device according to claim 1, wherein said device has an area of at least 0.05 m.sup.2.

13. The device according to claim 1, wherein said switching layer has a degree of anisotropy R of 0.7 to 0.9.

14. The device according to claim 1, wherein said switching layer has a degree of light transmission in the bright state .sub.v bright of 60% to 85%.

15. The device according to claim 1, wherein the following applies to the parameter T.sub.v bright of the switching layer for a given parameter R of the switching layer:
.sub.v bright min<.sub.v bright<.sub.v bright max and
.sub.v bright min=0.8*(67*R+30) and .sub.v bright max=1.2*(67*R+30).

16. The device according to claim 1, wherein the following applies to the parameter R of the switching layer for a given parameter T.sub.v bright:
R.sub.min<R<R.sub.max and
R.sub.min=0.8*(0.015*.sub.v bright0.45) and R.sub.max=1.2*(0.015*.sub.v bright0.45).

17. The device according to claim 1, wherein said device comprises two or more glass layers, and in that the degree of light reflection .sub.v in accordance with Standard EN410 of the totality of the layers of the device with the exception of the switching layer is less than 35%.

18. A window comprising multipane insulating glass and at least one device according claim 1.

19. A method for regulating the passage of light through a light-transmitting area into an interior space, said method comprising regulating said passage of light via passage through a device according to claim 1.

20. The device according to claim 1, wherein said device comprises two or more glass layers, and in that the degree of light reflection .sub.v in accordance with Standard EN410 of the totality of the layers of the device with the exception of the switching layer is less than 30%.

21. The device according to claim 1, further comprising a first electrode installed on one side of the switching layer and a second electrode installed on the other side of the switching layer, and wherein application of a voltage across the electrodes cause a change in the alignment of the molecules of the liquid-crystalline medium including the molecules of the at least one dichroic dye and a resultant change in the light transmission of the device.

22. The window according to claim 18, wherein said device is applied to the outside of a pane of the multipane insulating glass.

23. The window according to claim 18, wherein said device is positioned between two panes of the multipane insulating glass.

24. The device according to claim 1, wherein said device comprises the following arrangement of layers: 1) a first glass layer, 2) a first electrically conductive layer, 3) a first alignment layer, 4) said switching layer, 5) a second alignment layer, 6) a second electrically conductive layer, 7) a second glass layer, and 8) a third glass layer, wherein a free space is present between the second and third glass layers and where said free space is optionally filled with an insulating gas.

25. The device according to claim 1, wherein said device is a switchable device that provides for a change in the light transmission of the device, wherein the switching occurs by transition of the liquid-crystalline medium from a nematic state to an isotropic state due to a change in the temperature of the switching layer.

26. The device according to claim 1, wherein the proportion of all dichroic dyes together in the liquid-crystalline medium is in total 0.01 to 10% by weight.

27. The device according to claim 1, wherein the liquid-crystalline medium has a dielectric anisotropy greater than 3, an optical anisotropy (An) of 0.01 to 0.3, and a specific electrical resistance of greater than 10.sup.10 ohm*cm.

28. The device according to claim 1, wherein said liquid-crystalline medium comprises at least one of the following dichroic dyes: ##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035##

29. A window comprising multipane insulating glass and at least one device according claim 24 wherein which a first glass pane of the window is formed by a glass pane of said at least one device.

30. The device according to claim 1, wherein said liquid-crystalline medium comprises the following dichroic dyes: ##STR00036##

31. The device according to claim 1, wherein the difference between the degree of light transmission of the switching layer in the bright state .sub.v bright and the degree of light transmission of the switching layer in the dark state .sub.v dark is at least 25%.

Description

WORKING EXAMPLES

(1) In the present application, structures of liquid-crystalline compounds are reproduced by abbreviations (acronyms). These abbreviations are explicitly presented and explained in WO 2012/052100 (pp. 63-89), so that reference is made to the said published application for an explanation of the abbreviations in the present application.

(2) All physical properties are determined in accordance with Merck Liquid Crystals, Physical Properties of Liquid Crystals, Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20 C. The value of n is determined at 589 nm, and the value of is determined at 1 kHz, unless explicitly indicated otherwise in each case. n.sub.e and n.sub.o are in each case the refractive indices of the extraordinary and ordinary light beam under the conditions indicated above.

(3) A) Production of the Devices

(4) 1) Procedure for Construction of the Devices

(5) Devices E-1 to E-6 according to the invention and comparative devices V-1 to V-9 are produced.

(6) The devices according to the invention have the following layer sequence:

(7) a) glass layer comprising polished 1.1 mm soda-lime glass from Corning

(8) b) ITO layer, 200 angstrom

(9) c) alignment layer comprising polyimide AL-1054 from JSR, 300 angstrom

(10) d) liquid-crystalline layer (composition indicated under 2)), 24.3 m

(11) e) as c)

(12) f) as b)

(13) g) as a)

(14) The alignment layers are rubbed antiparallel.

(15) The ITO layers are provided with appropriate contacts in order to be electrically switchable.

(16) The comparative devices are constructed like the devices according to the invention, with the difference that one or both of the parameters .sub.v bright (degree of light transmission in the bright state) and R (degree of anisotropy) are outside the range according to the invention, due to the choice of host and/or dye and/or dye concentration in the switching layer.

(17) 2) Composition of the Guest/Host Mixtures of the Devices (E: According to the Invention, V: Comparison)

(18) TABLE-US-00002 Concentration of Host Dye dye/% by weight E-1 H-1 D-1 0.05 D-2 0.10 D-3 0.12 E-2 H-1 D-1 0.10 D-2 0.21 D-3 0.24 E-3 H-1 D-1 0.17 D-2 0.35 D-3 0.40 E-4 H-2 D-1 0.05 D-2 0.10 D-3 0.12 E-5 H-2 D-1 0.10 D-2 0.21 D-3 0.24 E-6 H-2 D-1 0.17 D-2 0.35 D-3 0.40 V-1 H-1 D-1 0.02 D-2 0.04 D-3 0.04 V-2 H-1 D-1 0.03 D-2 0.05 D-3 0.06 V-3 H-1 D-1 0.35 D-2 0.74 D-3 0.84 V-4 H-1 D-1 0.46 D-2 0.95 D-3 1.09 V-5 H-1 D-1 0.62 D-2 1.29 D-3 1.47 V-6 H-1 D-4 0.10 Lumogen 305 0.075 D-3 0.125 V-7 H-1 D-4 0.20 Lumogen 305 0.15 D-3 0.25 V-8 H-1 D-4 0.40 Lumogen 305 0.30 D-3 0.50 V-9 H-2 D-1 0.03 D-2 0.05 D-3 0.06
3) Composition of the Host Mixtures:

(19) TABLE-US-00003 H-1 H-2 Clearing point 77.5 C. 114.5 C. Dielectric anisotropy 11.3 10.5 Optical anisotropy n 0.1255 0.1342 Composition Compound % Compound % PZG-2-N 0.936 CPG-3-F 5 PZG-3-N 0.936 CPG-5-F 5 PZG-4-N 2.184 CPU-3-F 15 PZG-5-N 2.184 CPU-5-F 15 CP-3-O1 7.488 CP-3-N 16 CC-3-4 3.12 CP-5-N 16 CPP-3-2 2.496 CCGU-3-F 7 CCZGI-3-3 2.496 CGPC-3-3 4 CCZGI-3-5 2.496 CGPC-5-3 4 CCZPC-3-3 1.248 CGPC-5-5 4 CCZPC-3-4 1.248 CCZPC-3-3 3 CCZPC-3-5 0.936 CCZPC-3-4 3 CPZG-3-N 1.248 CCZPC-3-5 3 CGPC-5-3 1.248 CPPC-5-3 0.936 CPU-3-F 34.4 CPU-5-F 34.4
4) Structures of the Dyes:

(20) ##STR00030##

(21) The dye Lumogen 305 is commercially available from BASF SE.

(22) B) Determination of the Parameters .sub.v bright (degree of Light Transmission in the Bright State) and R (Degree of Anisotropy) and H (Range)

(23) 1) The degree of anisotropy R is determined at 550 nm from the value for the absorbance E(p) of a device comprising two glass sheets with alignment layers and liquid-crystalline medium comprising dichroic dyes arranged in between, with parallel alignment of the dye molecules, and the value for the absorbance E(s) of the same device with perpendicular alignment of the dye molecules. Parallel alignment of the dye molecules is achieved by an alignment layer. The absorbance of the device is measured against a device which comprises no dye, but has an otherwise identical construction. The measurement is carried out using polarised light whose plane of vibration in one case vibrates parallel to the alignment direction (E(p)) and in a subsequent measurement vibrates perpendicular to the alignment direction (E(s)). The sample is not switched or rotated during the measurement. The measurement of E(p) and E(s) is thus carried out via the rotation of the plane of vibration of the incident polarised light.

(24) In detail, the procedure is as described below: the spectra for measurement of E(s) and E(p) are recorded using a Perkin Elmer Lambda 1050 UV spectrometer. The spectrometer is fitted with a Glan-Thompson polariser for the wavelength range 250 nm-2500 nm in both the measurement and reference beams. The two polarisers are controlled by a stepping motor and are aligned in the same direction. A change in the polariser direction of the polariser, for example changeover from 0 to 90, is always carried out synchronously and in the same direction for the measurement and reference beams. The alignment of an individual polariser can be determined using a method which is described in the dissertation by T. Karstens, University of Wrzburg, 1973. In this method, the polariser is rotated in 5 steps against an aligned dichroic sample, and the absorbance is recorded at a fixed wavelength, preferably in the region of maximum absorption. A new zero line is run for each polariser position. For measurement of the two dichroic spectra E(p) and E(s), an antiparallel-rubbed test cell, coated with polyimide AL-1054 from JSR, is located in both the measurement and reference beams. The two test cells should be selected of the same layer thickness, typically 15-25 m. The test cell containing pure host (liquid crystal) is located in the reference beam. The test cell containing the solution of dye in liquid crystal is located in the measurement beam. The two test cells for measurement and reference beams are installed in the ray path in the same alignment direction. In order to guarantee the greatest possible accuracy of the spectrometer, it is ensured that E(p) is in the wavelength range of its greatest absorption, preferably between 0.5 and 1.5. This corresponds to transmissions of 30%-5%. This is set by corresponding adjustment of the layer thickness and/or dye concentration.

(25) The degree of anisotropy R is calculated from the measured values for E(p) and E(s) in accordance with the formula
R=[E(p)E(s)]/[E(p)+2*E(s)],
as indicated in Polarized Light in Optics and Spectroscopy, D. S. Kliger et al., Academic Press, 1990.

(26) 2) The degree of light transmission in the bright state .sub.v bright is indicated in percent. It is calculated from the spectral degrees of transmission in the bright state of a device comprising two glass sheets with alignment layers and liquid-crystalline medium comprising dichroic dyes arranged in between, relative to an otherwise identical device without dye in the liquid-crystalline medium as reference. The measurement set-up is the same as in the case of the measurements of the absorbances for the degree of anisotropy.

(27) The degree of light transmission .sub.v bright is determined in accordance with European Standard EN410, equation (1) (Determination of luminous and solar characteristics of glazing) from the measured spectral degrees of transmission taking into account the relative spectral distribution of the standard illuminant and the spectral degree of brightness sensitivity of the standard observer.

(28) 3) The range H is indicated in percent. It represents the difference between the degree of light transmission of the switching layer in the bright state of the device (.sub.v bright) and the degree of light transmission of the switching layer in the dark state of the device (.sub.v dark). The value .sub.v dark here is determined in accordance with the above-mentioned method for the measurement of .sub.v bright, while the device is switched into the dark state.

(29) 4) Values Obtained for Devices E-1 to E-6 and V-1 to V-9

(30) TABLE-US-00004 H/% (.sub.v bright .sub.v dark, .sub.v bright/% R in each case (in acc. with EN410) (550 nm) in acc. with EN410) E-1 87.5 0.68 29.7 E-2 74.6 0.74 33.3 E-3 62.0 0.73 29.9 E-4 89.3 0.77 30.2 E-5 79.2 0.75 35.2 E-6 68.0 0.77 32.5 V-1 94.3 0.73 15.6 V-2 92.9 0.75 20.1 V-3 36.9 ~0.73 17.5 V-4 29.4 ~0.73 13.5 V-5 17.9 ~0.73 7.9 V-6 82.3 0.50 20.2 V-7 67.1 0.49 24.6 V-8 44.3 0.49 20.1 V-9 93.8 0.79 20.7

(31) The examples show that devices having very different ranges Hbetween 7.9% and 35.2%are obtained depending on the choice of the parameters .sub.v bright and R.

(32) Desired ranges H in the region of 25% and higher (devices E-1 to E-6) are only achieved if the parameters .sub.v bright and R are selected suitably: R must have a value of at least 0.65, and .sub.v bright must be between 40 and 90%.

(33) If one or both of the parameters are selected outside this range, inadequate ranges H are achieved which are significantly less than 20%, in some cases less than 10% (comparative devices V-1 to V-9).

(34) The measurements show that basically low ranges are achieved in the case of a degree of anisotropy R selected too low (V-6 to V-8). It is irrelevant whether the value for .sub.v bright is selected high, as in Example V-6, or low, as in Example V-8.

(35) However, if the degree of anisotropy is sufficiently high (E-1 to E-6 and V-9), suitable ranges H can be achieved, but only in combination with suitable values for .sub.v bright, as shown by the example of V-9, in which, in spite of a suitable value for R, a satisfactory value for the range H is not obtained owing to the excessively high .sub.v bright.

(36) The measurements furthermore show that basically only low ranges are achieved in the case of inadequate bright transmission .sub.v bright, irrespective of whether a suitable value for R is present (V-5).

(37) The measurements furthermore show that satisfactory values for the range H cannot be achieved in the case of excessively high values for .sub.v bright (V-1, V-2 and V-9), irrespective of whether the value for the anisotropy R is high or low.

(38) The experiments therefore show in summary the surprising result that high ranges of the light transmission can only be achieved on combination of suitable values for the anisotropy with suitable values for the bright transmission .sub.v bright.

(39) The examples shown specifically serve for explanation and illustration of the invention. The person skilled in the art will be able to produce further devices within the scope of the claims by preparing liquid-crystalline media having a suitable degree of anisotropy. This succeeds with utilisation of his general expert knowledge and general basic correlations, such as, for example, the correlation between molecular structure and degree of anisotropy of a dye and the influence of the other compounds of the liquid-crystalline medium on these parameters. Devices having suitable bright transmission can be produced by a suitable choice of the absorbance of the dyes and concentration thereof in the switching layer.