EP2598563A1

EP2598563A1 - Polymethyl (meth)acrylate mouldings for fluorescence conversion, production of these by the sheet casting process and use in solar collectors

Info

Publication number: EP2598563A1
Application number: EP11734049.7A
Authority: EP
Inventors: Hans Lichtenstein; Claudius Neumann
Original assignee: Evonik Roehm GmbH
Current assignee: Evonik Roehm GmbH
Priority date: 2010-07-30
Filing date: 2011-07-05
Publication date: 2013-06-05
Also published as: US20130074930A1; WO2012013455A1; CN102958988A; TW201219462A; MX2012014778A; BR112013002210A2; JP2013534261A; DE102010038685A1; ZA201300689B

Abstract

The invention relates to a combination of fluorescence conversion dyes in plastics mouldings made of polymethyl (meth)acrylate, where these are used to convert natural insolation into light that can be used by the solar cells. The plastics mouldings are polymerized by the casting process.

Description

POLYMETHYL (METH) ACRYLA FORM BODIES FOR THE FLUORES EN CONVERSION, THEIR MANUFACTURE IN THE PLATEN CAST PROCESS, AND USE IN SOLAR COLLECTORS

Field of the invention

The invention relates to a combination of fluorescence conversion dyes in plastic moldings of polymethyl (meth) acrylate, which are used to natural sunlight over a particularly long period in for the

Convert solar cells to usable light. The plastic moldings are in

Casting polymerized.

State of the art

Photovoltaic cells can only partially convert the incident sunlight into usable electrical energy, a large part of the energy is lost in the form of heat. For example, a silicon solar cell can absorb all photons that have an energy above the band edge of 1.1 eV of the crystalline silicon. This corresponds to a wavelength <1 .100 nm. The excess energy of the absorbed photons is converted into heat and leads to a heating of the photocell, the efficiency of the photocell is lowered.

The structure and the effect of fluorescence conversion solar cells is known from US 4,110,123 (Fraunhofer) or from Appl. Phys. 14, 123 ff (1977). WO 2007/031446 (BASF AG) describes fluorescence conversion solar cells, composed of one or more glass plates or polymer plates, which with a Fluorescent dye are coated. As the fluorescent dye, dyes based on terrylenecarboxylic acid derivatives or combinations of these dyes with other fluorescent dyes are used. The disadvantage here is the separate

required step of coating the glass plates with the formulation containing the dye.

Concentrator systems with lenses or mirrors

Optical systems based on lenses or mirrors for the concentration of light on the solar cells are known, concentration factors of up to 1,000 times are achieved. A disadvantage of the optical solutions, however, is that the entire electromagnetic spectrum of the light is concentrated, so that not only the effective light is concentrated, but also the photovoltaic ineffective light. This leads to an undesirable thermal load on the solar cells and a reduction in the efficiency. In order not to let the temperatures get too high, you can actively or passively cool the solar cells. In addition, the lenses or the lens systems must be tracked consuming mechanically the position of the sun, they also can only reflect the directly incident light. Diffused light contributes little or no energy. (see US Patent 5,489,297)

task

In the light of the prior art discussed above, it has been the object to develop concentration paths for the optical radiation of the sun that are capable of • to use diffused light and therefore manage without complicated tracking mechanism,

To provide a light tuned to the absorption spectrum of the solar cell used (for example Si or GaAs),

• a concentration similar to the optical concentrators

achieve · easy and inexpensive to manufacture

• the heat load of the solar cells and the associated

To reduce efficiency loss, · to reduce the active solar cell area,

• to be resistant to weather conditions and during operation

practically do not change the optical properties,

solution

The solution of the above object is achieved by a use

various fluorescence conversion dyes in combination with special UV absorbers and optionally radical scavengers in plastic moldings, the spectra of the dyes are coordinated so that the incident light is radiated specifically with such wavelengths that are tailored to the respective solar cell. The solution further comprises the solution of the dyes or the dye mixtures in a monomer mixture, which is subsequently converted into a plastic molded article

is polymerized. The Kunststoffformkorper may be constructed in one or more layers and include layers containing the same or different dyes or dye mixtures. The individual layers may e.g. by gluing or by

Polymerization be firmly connected to each other. This can e.g. by methods described in applications DE 10233684 and DE 10254276.

But the stratification can also by loose stacking each other

Plastic moldings done.

The solution according to the invention offers the following advantages:

- The incident sunlight is in for silicon photovoltaic cells

converted to optimal wavelengths,

The production of the fluorescence conversion solar cells can after

known methods,

- The solar cells are protected against vandalism,

- the conversion rates are surprisingly high,

the Kunststoffformkorper is easily adaptable to the geometric and static requirements of the solar cell,

the plastic mold is lighter than a comparable arrangement of mineral glass, - The plastic molding can be equipped impact resistant, so that the solar cell array is protected against hail.

- The plastic molded body shows in comparison to similar, non-stabilized moldings, with weathering only a small decrease in the

Fluorescence intensity or even an increase.

The production of the plastic molding

The monomers

The (meth) acrylates A particularly preferred group of monomers are (meth) acrylates. The term (meth) acrylates includes methacrylates and acrylates as well as mixtures of both.

These monomers are well known. These include, among others

(Meth) acrylates derived from saturated alcohols, such as

Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, butoxymethyl (meth) acrylate,

Pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate,

Cyclohexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; (Meth) acrylates derived from unsaturated alcohols, such as oleyl (meth) acrylate,

2-propynyl (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate; Aryl (meth) acrylates, such as benzyl (meth) acrylate or phenyl (meth) acrylate, wherein the aryl radicals may each be unsubstituted or substituted up to four times;

Cycloalkyl (meth) acrylates, such as, for example, 3-vinylcyclohexyl (meth) acrylate, Bornyl (meth) acrylate; isobornyl (meth) acrylate, hydroxyalkyl (meth) acrylates such as 3-hydroxypropyl (meth) acrylate, 3,4-dihydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate; Glycol di (meth) acrylates such as 1,4-butanediol (meth) acrylate, (meth) acrylates of ether alcohols such as tetrahydrofurfuryl (meth) acrylate, vinyloxyethoxyethyl (meth) acrylate; Amides and nitriles of (meth) acrylic acid, such as

N- (3-dimethylaminopropyl) (meth) acrylamide, N- (diethylphosphono) (meth) acrylannide, 1-methacryloylamido-2-methyl-2-propanol; sulfur-containing methacrylates, such as, for example, ethylsulfinylethyl (meth) acrylate, 4-thiocyanatobutyl (meth) acrylate, ethylsulfonylethyl (meth) acrylate, thiocyanatomethyl (meth) acrylate,

Methylsulfinylmethyl (neth) acrylate, bis ((meth) acryloyloxyethyl) sulfide; polyvalent (meth) acrylates such as trimethyloylpropane tri (meth) acrylate.

These monomers may be used singly or as a mixture. In this case, mixtures are particularly preferred which contain methacrylates and acrylic esters.

The radical formers

The polymerization is generally started with known free-radical initiators. Among the preferred initiators include the azo initiators well known in the art, such as AIBN and 1,1-azobiscyclohexanecarbonitrile, as well as peroxy compounds such as methyl ethyl ketone peroxide, acetyl acetone peroxide,

Dilauryl peroxide, tert-butylper-2-ethylhexanoate, ketone peroxide,

Methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, 2,5-bis (2-ethylhexanoylperoxy) -2,5-dimethylhexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy-3 , 5,5-trimethylhexanoate, dicumyl peroxide, 1,1-bis (tert-butylperoxy) cyclohexane,

1, 1 -Bis (tert-butylperoxy) 3,3,5-trimethylcyclohexane, cumyl hydroperoxide, tert-butyl hydroperoxide, bis (4-tert-butylcyclohexyl) peroxydicarbonate, mixtures of two or more of the aforementioned compounds with one another and mixtures of aforementioned compounds with unspecified compounds which can also form radicals.

These compounds are often used in an amount of 0.01 to 1, 0 wt .-%, preferably from 0.05 to 0.3 wt .-%, based on the weight of the monomers.

The impact modifiers

Preferred impact-resistant castings which can be used to produce the polymethyl methacrylate molded body comprise 1% by weight to 30% by weight, preferably 2% by weight to 20% by weight, particularly preferably 3% by weight to 15% by weight .-%, in particular 5 wt .-% to 12 wt .-% by weight of an impact modifier, which is a

Elastomer phase of crosslinked Polymerisatteilchen represents. The impact modifier can in a conventional manner

Bead polymerization or by emulsion polymerization.

Preferred impact modifiers are crosslinked particles having an average particle size in the range of 50 to 1, 000 nm, preferably 60 to 500 nm and particularly preferably 80 to 120 nm.

Such particles can be obtained, for example, by the radical polymerization of mixtures which are generally at least 40% by weight, preferably 50% by weight to 70% by weight, of methyl methacrylate, 20% by weight to 80% by weight, preferably 25 wt .-% to 35 wt .-% butyl acrylate and 0.1 wt .-% to 2 wt .-%, preferably 0.5 wt .-% to 1 wt .-% of a crosslinking monomer, eg. B. a polyfunctional (meth) acrylate, such as. As allyl methacrylate and comonomers which can be copolymerized with the aforementioned vinyl compounds. Among the preferred comonomers are, inter alia, C 1 -C ₄ -alkyl (meth) acrylates, such as ethyl acrylate or butyl methacrylate, preferably methyl acrylate, or other vinylically polymerizable monomers, such as e.g. Styrene. The mixtures for the preparation of the aforementioned particles may preferably comprise 0 wt .-% to 10 wt .-%, preferably 0.5 wt .-% to 5 wt .-% comonomers.

Particularly preferred toughening modifiers are polymerizate particles which have a two-layer, particularly preferably a three-layer core-shell structure. Such core-shell polymers are described inter alia in EP-A 0 1 13 924, EP-A 0 522 351, EP-A 0 465 049 and EP-A 0 683 028.

Particularly preferred impact modifiers based on acrylate rubber have, inter alia, the following structure:

Core: polymer with a methyl methacrylate content of at least 90

Wt .-%, based on the weight of the core.

Shell 1: polymer having a butyl acrylate content of at least 80% by weight,

based on the weight of the first shell.

Shell 2: polymer having a methyl methacrylate content of at least 90

Wt .-%, based on the weight of the second shell. The core and the shells may each contain other monomers in addition to the monomers mentioned. These have been previously set forth, with particularly preferred comonomers having a crosslinking effect.

For example, a preferred acrylate rubber modifier may have the following structure:

Core: copolymer of methyl methacrylate (95.7% by weight), ethyl acrylate (4

% By weight) and allyl methacrylate (0.3% by weight), S1: Copolymer of butyl acrylate (81, 2 wt .-%), styrene (17.5 wt .-%) and

Allyl methacrylate (1, 3 wt .-%),

S2: copolymer of methyl methacrylate (96% by weight) and ethyl acrylate (4

Wt .-%)

The ratio of core to shell (s) of the acrylate rubber modifier can vary within wide limits. Preferably, the weight ratio of core to shell K / S is in the range from 20:80 to 80:20, preferably from 30:70 to 70:30 for modifiers with one shell or the ratio of core to shell 1 to shell 2 K / S1 / S2 in the range of 10:80:10 to 40:20:40, more preferably from 20:60:20 to 30:40:30 in modifiers with two shells.

The particle size of the core-shell modifier is customarily in the range from 50 to 1000 nm, preferably 100 to 500 nm and particularly preferably from 150 to 450 nm, without this being intended to limit it.

According to a particular embodiment, the polymethyl (meth) acrylate molded body has an E-modulus of at least 2,800 N / mm ² , preferably at least 3,300 N / mm ² according to ISO 527/2.

The plastic mold body can also be made of polycarbonate (PC), polystyrene (PS), polyamide (PA), polyester (PE), thermoplastic polyurethane (PU), polyethersulfone,

Polysulfones, vinyl polymers, such as polyvinyl chloride (PVC), be constructed.

Light stabilizers

UV stabilizers, UV stabilizers and free-radical scavengers and mixtures of the abovementioned compounds should be understood as meaning light stabilizers. The UV protection agents (UV absorbers) contained in the plastic molding according to the invention are

Derivatives of benzophenone, its substituents such as hydroxyl and / or

Alkoxy groups are usually in the 2- and / or 4-position. These include preferably 2-hydroxy-4-n-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4 , 4'-dimethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone. or substituted benzotriazoles selected from the group consisting of 2- [2-hydroxy-3,5-di- (alpha, alpha-dimethyl-benzyl) -phenyl] -benzotriazole, 2- (2-hydroxy-3,5-di -t-butylphenyl) - benzotriazole (Tinuvin 320), 2- (2-hydroxy-3, 5-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl ) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3 -sec-butyl-5-t-butylphenyl) benzotriazole and 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, phenol, 2,2 ^'- methylenebis [6- (2H-benzotriazole-2-yl) -4- (1,1,3,3-tetramethylbutyl)] or

UV absorbers of the class of the 2- ^{(2-hydroxyphenyl)} -1, 3,5-triazines, in particular 2- (4,6-diphenyl-1, 2,5-triazin-2-xy) -5- (hexyloxy ) phenol or

2-cyano-3,3-diphenylacrylic acid ethyl ester or substituted benzoic acid phenyl ester or

Compound according to formula (I)

wherein the radicals R ¹ and R ² independently represent an alkyl or cycloalkyl radical having 1 to 20, preferably having 1 to 8 carbon atoms. The aliphatic radicals are preferably linear or branched and may have substituents such as halogen atoms.

The preferred alkyl groups include methyl, ethyl, propyl, isopropyl, 1-butyl, 2-butyl, 2-methylpropyl, tert-butyl, pentyl, 2-methylbutyl, 1, 1 -Dimethylpropyl, hexyl, heptyl, octyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-decyl, 2-decyl, undecyl, dodecyl, pentadecyl and the eicosyl group.

Preferred cycloalkyl groups include the cyclopropyl, cyclobutyl,

Cyclopentyl, cyclohexyl, cycloheptyl and the cyclooctyl group, which are optionally substituted with branched or unbranched alkyl groups. Particular preference is given to 2-ethoxy-2'-ethyl-oxalic acid bisanilide, this compound being commercially available from Clariant under the trade name ^® Sanduvor VSU and from Ciba Geigy under the trade name ^® Tinuvin 312, or 2-ethoxy-5-t-butyl-2 '- ethyl-oxalsäurebisanilid used. The light stabilizers or UV protectants can be present as low molecular weight compounds, as indicated above, in the polymethacrylate compositions to be stabilized. But it can also UV-absorbing groups in the Matrix polymer molecules covalently after copolymerization with polymerizable UV absorption compounds, such as. As acrylic, methacrylic or allyl derivatives of

Benzophenone or benzotriazole derivatives, especially the o. G. Benzophenone or Beztrialzolderivate be bound.

The proportion of UV protection agents, which may also be mixtures of chemically different UV protection agents, is generally 0.01% by weight to 10% by weight, especially 0.01% by weight to 5% by weight. -%, In particular 0.02 wt .-% to 2 wt .-% based on the (meth) acrylate copolymer.

Examples of radical scavenger / UV stabilizers here are sterically hindered amines, which are known under the name HALS (Hindered Amine Light Stabilizer)

They can be used for the inhibition of aging in paints and plastics, especially in polyolefin plastics (Kunststoffe, 74 (1984) 10, pp. 620-623; paint + varnish, 96 vintage,

9/1990, pp. 689 to 693). The stabilizing effect of the HALS compounds is due to the tetramethylpiperidine group contained therein. This class of compounds may be both unsubstituted on the piperidine nitrogen and substituted with alkyl or acyl groups. The sterically hindered amines do not absorb in the UV range. They catch formed radicals, which the UV absorbers can not do.

Examples of stabilizing HALS compounds which can also be used as mixtures are:

Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro (4,5) decane-2,5-dione, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, poly (N-β-hydroxyethyl-2,2,6,6-tetramethyl-4-) hydroxy-piperidine-succinic acid ester) or bis (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate.

The radical scavengers / UV stabilizers are used in the polymer blends according to the invention in amounts of from 0.01% by weight to 15% by weight, especially in amounts from 0.02 wt .-% to 10 wt .-%, in particular in amounts of 0.02 wt .-% to 5 wt .-% based on the (meth) acrylate copolymer.

Antioxidants

As an antioxidant sterically hindered phenols or phosphites or phosphonites can be used. In the trade, these products are made by Ciba under the trademarks Irganox ^® and Irgafos ^®.

The casting process

For the plastic substrates produced by the cast-chamber method, for example, suitable (meth) acrylic mixtures are placed in a mold and polymerized. Such (meth) acrylic mixtures generally have the abovementioned (meth) acrylates, in particular methylnethacrylate. Furthermore, the (meth) acrylic mixtures may contain the copolymers described above and, in particular for adjusting the viscosity, polymers, in particular poly (meth) acrylates. The weight-average molecular weight M _{w of} the polymers produced by

Cast chamber processes are generally higher than that

Molecular weight of polymers used in molding compositions. This results in a number of known advantages. In general, the weight average molecular weight of polymers prepared by cast-chamber processes is in the range of 500,000 to 10,000,000 g / mol, without any of these

Restriction is to take place.

Furthermore, photoconductive layers of the present invention may be achieved by

Casting process can be produced. Here, suitable acrylic resin mixtures are placed in a mold and polymerized. A suitable acrylic resin includes, for example

1 . From 40% to 99.999% by weight of methyl methacrylate,

2. 0% by weight to 59.999% by weight of comonomers,

3. 0 wt .-% to 59.999 wt .-% in (1) or (2) soluble polymers,

4. 0.001 wt .-% to 0.1 wt .-% of one or more fluorescent dyes, wherein the components 1) to 4) together give 100 wt .-%.

In addition, the acrylic resin has the initiators necessary for the polymerization. The components 1 to 4 and the initiators correspond to the compounds which are also used for the preparation of suitable polymethyl methacrylate molding compositions.

For curing you can z. As the so-called Gußkammerverfahren (see, for example, DE 25 44 245, EP-B 570 782 or EP-A 656 548) apply, in which the polymerization of a plastic disc between two glass plates, which are sealed with a circulating string.

Preferred plastic substrates can be obtained from Evonik commercially under the trade name PLEXIGLAS ^® GS. The dimensions of the

Plastic substrates are for example (length X width X thickness) 2 m in length, 3 m wide and the thickness can be between 1, 5 mm to 200 mm, preferably plates with a thickness range between 2 mm and 20 mm, particularly preferred are plates in the thickness range from 3 mm to 10 mm. The dyes used

Fluorescent dyes

As dyes dyes of the types perylene, terrylene- and rylene derivatives can from the -Lumogen ^® - BASF, Rhodamine, LDS ^® series - series of exciton, substituted Pyrans (eg DCM), coumarins (eg coumarin 30, coumarin 1, coumarin 102, etc.) oxazines (eg Nile Blue or also called Nile Blue A), pyridines, styryl derivatives, dioxazines, naphthalimides, thiazines, silibens and cyanines (eg DODCI) from Z. B.

Lambdachrome® ^® and exciton ^® are used. The types of perylene, terrylene and rylene derivatives dyes are described in WO 2007/031446.

Also complex compounds of the lanthanides and nanoscopic semiconductor structures, so-called quantum dots, e.g. based on cadmium selenide, cadmium sulfide, zinc sulfide, lead selenide, lead sulfide and the like. are suitable for it. Preparation and use of the Quantum Dots are described in US 2007/0132052, US 2007/0174939, WO 0229140, WO

2004022637, WO 2006065054 and WO 2007073467.

Complex compounds of the lanthanides are described in CA 20072589575, EP 0767912 and in WO 9839822 and in Appl. Phys. Lett. 91, 051903 (2007), 23 ^rd European Photovoltaic Solar Energy Conference, Valencia, 700 (2008), Am. Chem. Soc. (2007), DOI

10.1021 / ja070058e described.

The photonic layer

The photonic layer is arranged on the plastic molded body, so that the sunlight must first penetrate this layer before the fluorescent dyes in the plastic molding can be excited to fluorescence as a photonic layer or wavelength-dependent mirrors are eg interference filter (stack filter, rugate filter, notch filter, etc. ), which may be constructed as a band-pass filter or edge filter, known. These are produced, for example, by depositing a plurality of thin dielectric layers having different refractive indices onto a substrate (see Olaf Stenzel, "The Physics of Thin Film Optical Spectra", Springer-Verlag) and (N.Kaiser, HK Pulker, Optical Interference Coatings). , Springer-Verlag). The layer thickness of the individual layer is generally smaller than the wavelength of light.

Another possibility is the use of photonic crystals, which are described in the following applications (DE 10024466, DE 10204338, DE 10227071, DE 10228228, DE 102004055303, US 6,863,847, WO 0244301, DE

DE 102004009569, DE 102004032120, WO 2006045567, DE 10245848, DE 102006017163)

These are small transparent spherical inorganic or organic bodies, which are arranged in the densest sphere packing. Depending on the size and spacing of the balls, they reflect light in a defined bandwidth and allow the remaining light to pass almost completely through this layer. Hollow-spherical structures can also be used. Then these are inverse opals. The individual spherical or hollow-spherical structures have the diameter of about 1/3 of the wavelength of light to be reflected (depending on the angle of incidence of the light and the distance of the balls).

The reflector

Optionally, to increase the yield, an optically reflecting shaped body, e.g. a mirror or a white foil or a plate.

The solar cells

The solar cell can be constructed of the usual materials, such as, for example, silicon solar cells Monocrystalline silicon (c-Si), multicrystalline silicon (mc-Si), amorphous silicon (a-Si), as well as tandem cells made of multicrystalline and amorphous silicon Ill-V semiconductor solar cells

Gallium arsenide (GaAs), gallium indium phosphide (GalnP), gallium indium arsenide (GalnAs), gallium indium arsenic phosphide (GalnAsP), gallium indium phosphide (GalnP), gallium antimonide (GaSb)

Likewise tandem cells (multiple solar cell) of gallium indium phosphide and gallium arsenide, of gallium indium arsenide and gallium indium arsenic phosphide, of gallium indium phosphide and gallium indium arsenide, of gallium arsenide and gallium antimonide or of gallium Arsenide and germanium or triple cells (triple solar cell) of gallium indium phosphide,

Gallium arsenide and germanium or gallium indium phosphide, gallium indium arsenide and gallium antimonide

Il Vl semiconductor solar cells

Cadmium telluride (CdTe), cadmium sulfide (CdS)

I-III V-Semiconductor Solar Cells

CIS cells: copper indium diselenide (CulnSe2) or copper indium disulfide (CulnS2)

CIGS cells: copper indium gallium diselenide (CulnGaSe2)

Copper Gallium Diselenide (CuGaSe2), Copper Gallium Disulfide (CuGaS2) • There are also recent developments of solar cells based on organic materials.

The following table shows some examples of semiconductors for solar cells. The indicated wavelength corresponds to the wavelength of the light which provides the energy equal to the energy of the energy gap of the semiconductor, i. With this light, the semiconductor works most effectively as a solar cell (the fluorescence conversion cell is tuned to this wavelength).

Cell material energy gap wavelength [nm]

[EV]

Ge 0.66 1879

GaSb 0.73 1708

CulnSe2 1.0 1240

Si 1.12 1107

GalnAs 1.24-1.39 998 - 891

GaAs 1.42 873

CulnS2 1.55 800

CdTe 1.56 795

GalnP 1.64-1.81 756 - 687

CuGaSe2 1.68 738

a-Si: H 1.7 729

Cu GaS2 2.30 539

CdS 2,42,512 Implementation of the invention

Examples The following examples serve to illustrate and to improve

However, understanding the present invention in no way limits it.

Description of the Preparation of Luminescent Solar Concentrators Reference Example R1: Preparation of a homogeneously colored plate

In 1, 000 weight parts of a prepolymeric Metylmethacrylat syrup (viscosity about 1, 000 cP) is 1 weight part of 2, 2 ^'azobis dissolved (2,4-dimethylvaleronitrile). Subsequently, a mixture consisting of

0.15 parts by weight of Lumogen Yellow 083 (BASF)

0.16 parts by weight of Lumogen Orange 240 (BASF)

0.40 parts by weight of Lumogen Rot 305 (BASF).

The batch is stirred vigorously, filled into a silicate glass chamber which is distanced with 10 mm thick cord and polymerized in a water bath at 45 ° C. for about 16 hours. The final polymerization is carried out in a tempering at 1 15 ° C for about 4 hours.

This gives a homogeneous red fluorescent plate of 10 mm thickness. Reference Example R2: Device with three layers

Green cover:

Inl OOO weight parts of Prepolymer Metylnnethacrylat syrup (viscosity about 1, 000 cP) is 1 weight part of 2,2 ^'azobis dissolved (2,4-dimethylvaleronitrile).

Then be

0.15 parts by weight of Lumogen Yellow 083 (BASF) was added.

The mixture is stirred intensively, in a 3mm thick string distanced

Silicate glass chamber filled and in a water bath at 45 ° C for about 16 hours

polymerized. The final polymerization is carried out in a tempering at 1 15 ° C for about 4 hours. Red cover:

In 1000 weight parts of Prepolymer Metylmethacrylat syrup (viscosity about 1000 cP) is 1 weight part of 2,2 ^'azobis dissolved (2,4-dimethylvaleronitrile). Then be

0.40 parts by weight of Lumogen Rot 305 (BASF) was added.

The mixture is stirred intensively, in a 3mm thick string distanced

Silicate glass chamber filled and in a water bath at 45 ° C for about 16 hours polymerized. The final polymerization is carried out in a tempering at 1 15 ° C for about 4 hours.

Inside:

In 1, 000 weight parts of Prepolymer Metylmethacrylat syrup (viscosity about 1, 000 cP) is 1 weight part of 2, 2 ^'azobis dissolved (2,4-dimethylvaleronitrile). Then be

0.16 parts by weight of Lumogen Orange 240 (BASF) was added.

The batch is stirred vigorously, filled into a 3mm thick cord spaced compartment formed of the green and red covers, and polymerized in the water bath at 45 ° C for about 16 hours. The final polymerization takes place in

Tempering cabinet at 1 15 ° C for about 4 hours.

A three-layered fluorescent plate with a total thickness of 9 mm is obtained.

Result

From the experiments according to Ex.1 and 2 samples were cut in the dimensions of about 10x10mm and polished on all edges. Subsequently, the

Fluorescence intensity measured on a fluorescence spectrophotometer LS-55 (Perkin Elmer). For excitation, a daylight-like xenon light source was used.

The maximum intensities and the associated wavelengths are recorded in Tab. Table 1

The experiment after R2 shows a much higher intensity.

Furthermore, attempts at long-term stability of the fluorescently colored

PLEXIGLAS ^® samples carried out. The climatic test was carried out according to the standard DIN EN ISO 4892 Part 2, Cycle 1 ^b . The specimens are at controlled

Ambient conditions (temperature, humidity and wetting) filtered

Exposed to xenon lamp radiation.

For humidity-sensitive test materials we recommend a relative humidity of (65 ± 10)%.

The samples heat up to the maximum temperature of 65 ± 3 degrees Celsius.

The samples for Examples B1 to B3 and Comparative Examples V1 to V3 were prepared analogously to the method of Reference Example R1. Table 2: Relative fluorescence intensity values after weathering

The data show that the stabilized samples show a significant increase in fluorescence intensity after 10,000 hours of weathering compared to the unstabilized samples. The samples were measured in a fluorescence spectrophotometer LS55 (manufacturer: Perkin Elmer). In this case, white artificial daylight is irradiated onto the surface of the sample and the light signal emerging at the edge is measured. The measured variable was the peak height of the measuring signal.

Reference Example R4: Preparation of a homogeneously colored plate without light stabilizer

Orange cover: in 1000 weight parts of Prepolymer Metylmethacrylat syrup (viscosity about 1, 000 cP) are dissolved 1 part by weight of 2,2 ^'azobis (2,4-dimethylvaleronitrile). Then be

0.5 parts by weight of Lumogen Orange 240 (BASF) added.

The mixture is stirred intensively, in a 3mm thick string distanced

Silicate glass chamber filled and in a water bath at 45 ° C for about 16 hours

polymerized. The final polymerization is carried out in a tempering at 1 15 ° C for about 4 hours.

Comparative Example C4: Preparation of a homogeneously colored plate with unsuitable light stabilizer (comparative example)

Orange cover:

In 1000 weight parts of Prepolymer Metylmethacrylat syrup (viscosity about 1, 000 cP) is 1 weight part of 2,2 ^'azobis dissolved (2,4-dimethylvaleronitrile).

Then be

1, 0 parts by weight Tinuvin P and

0.5 parts by weight of Lumogen Orange 240 (BASF) added.

The mixture is stirred intensively, in a 3mm thick string distanced

Silicate glass chamber filled and in a water bath at 45 ° C for about 16 hours

polymerized. The final polymerization is carried out in a tempering at 1 15 ° C for about 4 hours. Example B5: Preparation of a homogeneously colored plate with suitable light stabilizer

Orange cover:

Then be

1, 0 parts by weight SANDUVOR VSU and

0.5 parts by weight of Lumogen Orange 240 (BASF) added.

The mixture is stirred intensively, in a 3mm thick string distanced

Silicate glass chamber filled and in a water bath at 45 ° C for about 16 hours

Example B6: Preparation of a homogeneously colored plate with

suitable sunscreen

Orange cover:

In 1000 weight parts of Prepolymer Metylmethacrylat syrup (viscosity about 1, 000 cP) is 1 weight part of 2,2 ^'azobis dissolved (2,4-dimethylvaleronitrile). Then be 1, 0 parts by weight Tinuvin 320 and

0.5 parts by weight of Lumogen Orange 240 (BASF) added.

The mixture is stirred intensively, in a 3mm thick string distanced

Silicate glass filled and polymerized in a water bath at 45 ° C for about 16 hours. The final polymerization is carried out in a tempering at 1 15 ° C for about 4 hours.

Result

From the experiments to Ex 9, 10, 1 1 and 12, samples were cut in the dimensions of about 10x50mm and polished on all edges. Subsequently, the fluorescence intensity was measured on a fluorescence spectrophotometer LS-55 (Perkin Elmer). For excitation, a daylight-like xenon light source was used.

The maximum intensities and the associated wavelengths are recorded in Tab. Table 3

The experiment according to Comparative Example 4 shows a significantly lower intensity. Examples 5 and 6 show a comparable or better intensity but, analogously to the results of Table 2, a significantly better weathering behavior. Description of the Figures 1 Photonic layer

2 Homogeneously colored luminescent fluorescence collector

21, 22, 23 multi-layered luminescent fluorescent collector

3 reflector, z. Mirror or white plate

4, 41, 42, 43 adapted to fluorescence collector solar cells

3.1 light source

3.2 Surface of the sample

3.3 edge of the sample

3.4 detector

Claims

claims

Single or multilayer plastic molded article of polymethyl (meth) acrylate, characterized in that it is colored with at least one fluorescent dye and that it contains at least one UV absorber, wherein the UV absorber is a derivative of benzophenone, its substituents such as hydroxyl and / or alkoxy groups are in the 2- and / or 4-position, preferably 2-hydroxy-4-n-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 ', 4,4' Tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone or 2-hydroxy-4-methoxybenzophenone. or a substituted benzotriazole selected from the group consisting of 2- [2-hydroxy-3,5-di- (alpha, alpha-dimethyl-benzyl) -phenyl] -benzotriazole, 2- (2-hydroxy-3,5- di-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3-5-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) -5 -chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) -benzotriazole, 2- (2-hydroxy-5-t-butyl-phenyl) -benzotriazole, 2- (2-hydroxy-3-sec- butyl-5-t-butylphenyl) -benzotriazole and 2- (2-hydroxy-5-t-octylphenyl) -benzotriazole, phenol, 2,2 ^, -methylenebis [6- (2H-benztriazol-2-yl) -4- ( 1, 1, 3,3, -tetramethylbutyl)] or a UV-absorber of the class of the 2- ^{(2-hydroxyphenyl)} -1, 3,5-triazines, preferably 2- (4,6-diphenyl-1, 2,5-triazin-2-xy) -5- ( hexyloxy) phenol or

2-Cyano-3,3-diphenylacrylic acid ethyl ester or a substituted benzoic acid phenyl ester or a compound according to formula (I) wherein the radicals R ¹ and R ² independently represent a substituted or unsubstituted alkyl or cycloalkyl radical having 1 to 20, preferably having 1 to 8 carbon atoms, which may be linear or branched, particularly preferred 2-ethoxy-2'-ethyl-oxalsäurebisanilid or 2-ethoxy-5-t-butyl-2'-ethyl oxalic acid bisanilide or a UV-absorbing group which in the matrix polymer molecules covalently after copolymerization with polymerizable UV absorption compounds, in particular acrylic, methacrylic or allyl derivatives of benzophenone or benzotriazole derivatives, is bound

is. Plastic molding of polymethyl (neth) acrylate according to claim 1, characterized in that it comprises a HALS compound, preferably selected from the group consisting of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 8- Acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro (4,5) -decane-2,5-dione, bis- (2,2,6,6-tetramethyl- 4-piperidyl) succinate, poly (N-.beta.-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxy-piperidine-succinic acid ester) or bis (N-methyl-2,2,6,6- tetramethyl-4-piperidyl) sebacate, more preferably in an amount of from 0.01% to 15%, most preferably from 0.02% to 10%, and most preferably in Amounts of 0.02 wt .-% to 5 wt .-% based on the (meth) acrylate copolymer containing.

Plastic moldings of polymethyl (meth) acrylate according to claim 1 or 2, characterized in that it is composed of several individual plastic moldings or individual bonded plastic moldings which are colored with at least one fluorescent dye.

Plastic moldings of polymethyl (meth) acrylate according to one of claims 1 to 3, characterized in that it consists of a plurality of plastic moldings, which are polymerized by polymerization of one or more plastic moldings, which are colored with at least one fluorescent dye, between two further Kunstoffformkörpern containing at least one or at least one other fluorescent dye are colored, are formed, is constructed.

Plastic moldings of polymethyl (meth) acrylate according to one of the preceding claims, characterized in that it is colored with at least one organic fluorescent dye, preferably selected from the group consisting of organic fluorescent dyes based on rylene, perylene, terrylene and / or quaterrylene.

Plastic molding of polymethyl (meth) acrylate according to one of the preceding claims, characterized in that it is colored with at least one dye based on complex lanthanoid compounds or on the basis of nanoscopic semiconductor structures (quantum dots).

Process for producing a plastic molded body

Polymethyl (meth) acrylate according to one of Claims 1 to 6, characterized in that it is produced in a casting process which comprises the following steps: dissolving the dyes or the dye mixture in a monomer mixture, transferring the monomer mixture into a chamber and then

Polymerization by increasing the temperature.

8. Arrangement of a plastic molding according to one of claims 1 to 6 and a solar cell.

9. Arrangement according to claim 8, characterized in that a photonic layer, preferably a photonic layer which is formed as an inverse opal or which is composed of photonic crystals or from a dielectric interference filter, particularly preferably from a dielectric interference filter, as an edge filter or Bandpass filter is formed, is arranged on the Kunststoffformkorper.

10. Arrangement according to claim 8 or 9, characterized in that a planar reflector, preferably a mirror or a white film or a white plate is arranged under the plastic moldings.

1 1. Arrangement according to claim 10, characterized in that a photonic layer on the Kunststoffformkorper and a reflector under the Kunststoffformkorper are arranged.

12. Use of a plastic molding according to one of the claims 1 to 6 for the production of solar collectors.

13. Use of an arrangement according to one of the claims 9 to 1 1 for the production of solar collectors.