DE102006062448A1 - Photovoltaic module with thin electrode- and silicon layers, for solar energy collection, includes high-refraction glass or glass-ceramic converter plate containing specified dopants - Google Patents

Abstract

The converter plate, which is made from glass or glass-ceramic, has a refractive index of at least 1.49 and is doped with at least one non-ferrous heavy metal and/or at least one rare earth metal. The non-ferrous heavy metal dopant comprises MnO2, CrO3, NiO and/or a combination of these. The rare earth dopant comprises a bi- or tri-valent oxide or fluoride of samarium, europium, thulium, terbium, yttrium, ytterbium and/or a combination of them. Suitable glass types are presented, together with their quantified composition ranges. The photovoltaic module has an additional cover glass. This is UV-blocking. It contains 0.05-0.5 wt% TiO2, based on the total quantity of cover glass. Water content is less than 40 mmol/l. Nanocrystals are included. Their size is less than 200, 50 or 30 nm, and especially less than 10 nm.

Description

The The present invention relates to a photovoltaic module comprising an electrode layer, in particular thin-film silicon and a converter plate of doped glass and / or doped glass-ceramic

The Use of solar energy as an alternative source of energy decreases in view of the scarcity of raw materials an ever higher priority one. However, solar energy is relative to fossil fuels expensive.

At the Use of a photovoltaic system turns solar energy into electric Energy converted. These equipments are meanwhile on the whole World used for power generation and find applications on roofs, at parking ticket machines, at noise barriers and on Open spaces.

in the State of the art are photovoltaic modules with different solar converters known. For example, a solar converter or solar concentrator to increase solar absorption and energy transfer used by luminescence in the red spectral region, in the silicon already shows a nearly perfect efficiency.

Of the Solar converter consists of either a thin one Plexiglas pane containing organic colorants or inorganic Semiconductor quantum dots is doped. To the fullest possible Visible absorption will be multiple colorants with each investigated different absorption areas. A problem with it lies in the fact that the emission and excitation bands of the colorants spectrally agree otherwise Energy is converted without radiation.

Also are there still no phosphors / phosphors for the NIR and IR range with relative quantum efficiency> 50%, which helps to avoid self-absorption necessary is. This is due to the hydrolysis sensitivity of these Colorant. Furthermore, basically only refractive indices are in a range of 1.40 to 1.45 possible, so that high reflection losses are to be accepted.

Another prior art system, referred to as a hybrid system, provides a multilayer system of ITO, TiO ₂ and porous TiO ₂ for incorporation of the organic phosphors (phosphors from Evidentec, the manufacturer of fluorescent labels) via diffusion.

Also it is known absorber antennas based on organic colorants doped zeolite and textured absorber plates apply.

Further become the focus of the entire solar spectrum up to the factor 300-400 microlens arrays (ISOFOTON, Spain). At the moment, however, there is only one focus of the visible spectral range possible.

One Degradation protection is intended by using cover glass with UV edge be reached at about 380 nm.

The Disadvantages of the prior art are that almost exclusively Plastics are used. In plastics, it may be due to the high sunlight concentration due to heating to a degradation of plastics and beyond to long-term damage come. In addition, the energy transfer is not in the entire spectral range optimal (red fluorescent Dyes).

For example, it has already been proposed in the prior art to substitute plastics with a glass or a glass ceramic. The DE-C-3305853 sees glass or glass-ceramic containing Yb ₂ O ₃ , Nd ₂ O _3, and Cr ₂ O ₃ as the material for fluorescent sun collectors. The oxides are present in the following concentration ranges: Yb ₂ O ₃ 0.5-10% by weight Nd ₂ O ₃ 0.5-5% by weight Cr ₂ O ₃ 0.005-8% by weight

The DE-A-1955174 describes glass-ceramics which are suitable as host material for activation ions. It was found that during the incorporation of ions from the group of rare earths into these Glass ceramics these can be excited to luminescence. In particular, the use of neodymium and ytterbium is discussed.

A solar concentrator plate with a dye incorporated therein is known from US-A-4,661,649 known, wherein the dye is incorporated in a thin film of glass or plastic materials.

In the US-A-4367367 a solar collector is described containing doped glass plates. As dopants are organic Fluophore or dyes or uranyl and non-ferrous metals analogous to DE-A-1955174 used.

Further prior art fluorescent materials made of glass / glass ceramic are oxidic glass or glass ceramics with Dopants of Yb, Nd and Cr. The doping level is in the range 0.5-10 wt .-% for Yb and Nd and in the range of 0.005-0.8 wt% for Cr. At the same time, the doping levels become in terms of concentration quenching, minimal overlay optimally adjusted by excitation and emission bands.

chrome serves as sentizer, d. H. as an amplifier due Energy transfers to the Yb and Nd ions. The absorption takes place usually at 400-800 nm and emission at 800-1200 nm. The base material used is silicate, borate or phosphate glass. The fluorescent light is thereby on the side surfaces of the converter and the front surfaces collected. The weathering and solarization resistance is increased by UV-blocking cover glass.

Of the The present invention is based on the object, a photovoltaic module to provide with a converter plate, with the reflection losses be reduced.

The Invention has the solution to this problem in the claim 1 specified characteristics. Advantageous embodiments thereof are given in the further claims.

According to the invention a photovoltaic module comprising an electrode layer, in particular thin-layer silicon and a converter plate, characterized is that the converter plate made of doped glass or glass ceramic has a refractive index n with n ≥ 1.5 and at least one Non-ferrous metal and / or at least a rare earth metal is doped.

In the investigation of glass-based fluorescence reference materials with regard to depletion, emission, quantum yield and UV stability, it was surprisingly found that, in particular, lanthanum phosphate glasses have suitable conversion properties:
First, the higher refractive index of n> 1.5 should be mentioned. Plastics have a refractive index in the range of 1.4 ≤ n ≤ 1.45 in comparison.

The refractive index is given among other things by the specific ion weight of the synthesized elements, ie refractive index n α Zn, n = 0.5 to 2. Optical glass of the type N-PK52a contains 18-19% barium and 17-18% strontium. The refractive index thus set is n _d (589 nm) = 1.495. Another example is the opt. Glass LF5, which contains 32-34% PbO and has a refractive index of more than 1.58 at 589 nm.

alternative can also be used LAS glass-ceramic materials (refractive index> 1.57), containing more than 5% zirconia.

A further increase in refractive power is due to a higher Density ρ of the glass achieved, since n α ρ. This is offset by an increase in fluorine content reached the oxygen content, with the built-in fluorine ions a higher molar bond is achieved.

The Surface reflection losses are due to the use of glass or glass ceramics according to the invention significantly reduced.

The converter plate according to the invention is doped with non-ferrous metals and / or rare earth metals. The non-ferrous metals are selected from the group consisting of MnO ₂ , CrO ₃ , NiO and / or a combination thereof.

The rare earth metals are selected from the group consisting of divalent or trivalent oxides and fluorides of samarium, europium, thulium, terbium, yttrium and ytterbium and / or a com combination of it.

It is preferred that the glass composition is selected from one of the following glass compositions: a) Type N-PK52A element Share in weight percent Base glass (all elements except F as oxides), allowable range al 7.784% (m / m), 5-10% Ba 18.726% (m / m), 15-20% Ca 6.618% (m / m), 5-9% F 27.331% (m / m), 25-29% mg 1.979% (m / m), 0.5-3% N / A 0.051% (m / m), 0.01-0.1% Nb 0.259% (m / m), 0.1-0.3% O 14,073% (m / m), 10-18% P 6.713% (m / m), 4-8% sb <0.02% (m / m), 0.0-0.1% Si <0.02% (m / m), 0.0-0.1% Sr 17.313% (m / m), 15-19% allocations: Cr 0.01-0.05% (m / m) Mn 0.01-0.2% (m / m) sm 0.01-0.05% (m / m) Ni 0.01-0.05% (m / m) additional allocations Y, Yb, Eu, Tm, Tb 0.01-2% (m / m) as di- and trivalent oxides and fluorides b) Type FK-51/52 element Share in weight percent Base glass, allowable range Al ₂ O ₃ 12.9% (m / m), 11-16% BaO 20.3% (m / m), 18-22% CaO 10.3% (m / m), 9-12% F 28.7% (m / m), 25-30% La ₂ O ₃ 1.47% (m / m), 0.5-2.0% MgO 5.19% (m / m), 4-8% Na ₂ O 3.87% (m / m), 2-5% P ₂ O ₅ 15.1% (m / m), 12-18% SrO 13.2% (m / m), 12-15% allocations: Cr 0.01-0.05% (m / m) Mn 0.01-0.2% (m / m) sm 0.01-0.05% (m / m) Ni 0.01-0.05% (m / m) Additional allocations: Y, Yb, Eu, Tm, Tb 0.01-2% (m / m), as di- and trivalent oxides and fluorides c) Type LEX element % (m / m) permissible range basic glass Al ₂ O ₃ 8857 6-10 P ₂ O ₅ 71267 65-75 Na ₂ O 6388 6-10 La ₂ O ₃ 10669 8-12 allocations: NiO 0:01 to 12:05 a.m. MnO ₂ 0.01-0.2 Sm ₂ O ₃ 0:01 to 12:05 a.m. Cr ₂ O ₃ 0:01 to 12:05 a.m. Additional allocations: Y, Yb, Eu, Tm, Tb 0.01-0.2 as trivalent fluorides

Further it is to increase the weathering and solarization resistance preferred that the photovoltaic module further comprises a cover glass Includes UV blocking.

The cover glass contains TiO ₂ in a proportion of 0.05-0.5 wt .-%, based on the total amount of the cover glass.

Also it is preferred that the water content is less than 40 mmol / l, preferably less than 10 mmol / l, more preferably less than 1 mmol / l is. This improves the optical properties.

By reducing the water content, the transmission in the relevant for the solar spectrum NIR range (850-3000 nm), in particular at 1400 and 2700 nm, improved. This leads to a reduction of the photon excitation, which in turn be a reduction in the quantum yield of fluorescence be would work.

Also It is preferred that nanocrystals with a size of less than 200 nm are included. Because of the size The generated nanocrystals in the glass-ceramic are optical properties such as absorption and diffuse scattering via the process control specifically adjustable. The nanocrystals can also be smaller than 50 nm or less than 30 nm or less than 10 nm.

Also is a concentration of the converted sunlight possible, because the fluorescence emission radiates isotropically. Furthermore, one is Concentration quenching via the determination of the emission decay behavior preventable.

Further Advantages of using the invention Glass compositions are given below.

For trivalent rare earth ions doping levels up to 3 wt .-% z. As for Sm ₂ O ₃ , possible without changing the decay times of the emissions. This is because optically forbidden transitions are excited.

In the case of bivalent rare earth ions and non-ferrous metal ions, this limit value is lower since optically permissible transitions are excited here. Examples: Cr ₂ O ₃ : 0.25 wt .-%, NiO: 0.05 wt .-%, MnO ₂ : 1.2 wt .-%.

It New Sentizizer ions (nickel, manganese) were found, the one Allow extension of the absorption range to 380 nm, since here again optically allowed transitions are used.

Also, a higher variation of the total doping level over that in the DE-C-3305853 concentrations are possible because more than two dopant ions are used and the absorption is distributed over more than two dopants (see also Example 2).

The glasses / glass ceramics according to the invention are more stable to solarization than those in the DE-C-3305853 specified glasses (anhydrous melting, purity of raw materials).

The optically pure raw materials used, for. B. Treibacher, contain max. 5 ppm CeO ₂ , 10 ppm Nd ₂ O ₃ and 5 ppm Fe ₂ O ₃ .

cleaner Raw materials (CERAC) have a level of 2 ppm each. For high purity Raw materials (Merck), these values are even below 0.5 ppm.

The water content can be controlled by anhydrous raw materials and the addition of refining agents (eg As ₂ O ₃ ).

The Solarization properties by using pure raw materials with an iron content of less than 200 ppm by weight, preferably less than 50 wt ppm, more preferably less than 10 wt ppm is improved.

Prefers it is that the doping degree is chosen so that no Concentration quenching occurs. A concentration quenching occurs when the excited fluorescent ion has a lower cooldown (or Lifetime) gets that by having an adjacent ion of the same or similar species is "disturbed." This Disorder manifests itself in absorption of the excited level or in an energy level decomposition the additional decay channels arise, the lead to a measurably faster decay of fluorescence.

The determination of whether concentration quenching occurs is therefore based on the determination of the decay time. Such equipment is offered by the companies Horiba / IBH and Pigiquant. The cooldown values given in this work were determined using these two diagnostics. In the drawing, the decay times for doping with manganese (Mn ²⁺⁾ and chromium (Cr ^{+ 3)} are shown for various single-Dotiergrade. In addition, the example of a sample with 2 dopants (manganese and chromium) shows that the addition of a further doping does not lead to a quenching of the fluorescence.

The Avoiding quenching is to be ensured as the light or Quantum yield is directly proportional to the cooldown.

Further Details, advantages and features of the invention do not arise only from the claims, the features to be taken from them - for itself and / or in combination - but also from the following Description of the drawing and the embodiments.

It demonstrate:

1 Energy transfer from UV to NIR by doping of the glass of the type N-PK52A with manganese and

2 Energy transfer from UV to NIR by doping a glass of the type N-PK52A with chromium.

The energy transfer from UV to NIR by doping of the glass of the type N-PK52A with Mn ^{2 +} or Cr ³⁺ ions can be seen purely in principle in the figures. The in the 1 solid line represents the excitation spectrum and the dashed line represents the emission spectrum 2 the more dashed curve the excitation spectrum and the thinner curve drawn with a maximum in the region of 830 nm the emission spectrum.

The following are the different types of glass with different doping and doping levels and the decay times for doping with chromium and manganese. glass type endowment Degree of doping in ppm by weight Emission% _max in nm Cooldown in ms FK 51/52 Cr 100 750 13.2 LEX Cr 500 750 13.0 N-PK52a Cr 2000 750 13.0 N-PK52a Cr & Mn 2000 & 1500 750 12.7 LEX Cr 2500 750 9.5 FK 51/52 Mn 100 590 22.0 FK 51/52 Mn 500 590 21.2 N-PK52a Mn 1500 590 21.0 N-PK52a Mn & Cr 1500 & 2000 590 20.9 LEX Mn 15000 590 18.7

you realizes that a reduction in cooldowns in the examined Glasses only from 5 to a chromium concentration of 2500 ppm (0.25%) occurs. For manganese, this value is even 1.25%. This limit seems to be independently surprising from the glass composition of the examined glasses. From silicate glass matrices it is known that quenching already can occur from 1000 ppm

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3305853 C [0012, 0039, 0040]
• DE 1955174A [0013, 0015]
• - US 4661649 A [0014]
• US 4367367A [0015]

Claims (8)

Photovoltaic module, comprising an electrode layer, in particular thin-film silicon and a converter plate of doped glass and / or doped glass ceramic, characterized in that the existing glass or glass ceramic converter plate has a refractive index n of at least 1.49 and at least one non-ferrous metal and / or doped at least one rare earth metal. Photovoltaic module according to claim 1, characterized in that the non-ferrous metals are selected from the group consisting of MnO ₂ , CrO ₃ , NiO and / or a combination thereof. Photovoltaic module according to claim 1, characterized in that that the rare earth metals are selected from the group, consisting of divalent or trivalent oxides and fluorides of Samarium, europium, thulium, terbium, yttrium and ytterbium and / or a combination of them. Photovoltaic module according to one of claims 1-3, characterized in that the glass is selected from one of the following glass compositions: a) type N-PK52A element Share in weight percent Base glass (all elements except F as oxides), allowable range al 7.784% (m / m), 5-10% Ba 18.726% (m / m), 15-20% Ca 6.618% (m / m), 5-9% F 27.331% (m / m), 25-29% mg 1.979% (m / m), 0.5-3% N / A 0.051% (m / m), 0.01-0.1% Nb 0.259% (m / m), 0.1-0.3% O 14,073% (m / m), 10-18% P 6.713% (m / m), 4-8% sb <0.02% (m / m), 0.0-0.1% Si <0.02% (m / m), 0.0-0.1% Sr 17.313% (m / m), 15-19% allocations: Cr 0.01-0.05% (m / m) Mn 0.01-0.2% (m / m) sm 0.01-0.05% (m / m) Ni 0.01-0.05% (m / m) additional allocations Y, Yb, Eu, Tm, Tb 0.01-2% (m / m) as di- and trivalent oxides and fluorides b) Type FK-51/52 element Share in weight percent Base glass, allowable range Al ₂ O ₃ 12.9% (m / m), 11-16% BaO 20.3% (m / m), 18-22% CaO 10.3% (m / m), 9-12% F 28.7% (m / m), 25-30% La ₂ O ₃ 1.47% (m / m), 0.5-2.0% MgO 5.19% (m / m), 4-8% Na ₂ O 3.87% (m / m), 2-5% P ₂ O ₅ 15.1% (m / m), 12-18% SrO 13.2% (m / m), 12-15% allocations: Cr 0.01-0.05% (m / m) Mn 0.01-0.2% (m / m) sm 0.01-0.05% (m / m) Ni 0.01-0.05% (m / m) Additional allocations: Y, Yb, Eu, Tm, Tb 0.01-2% (m / m), as di- and trivalent oxides and fluorides c) Type LEX element % (M / m) permissible range basic glass Al ₂ O ₃ 8857 6-10 P ₂ O ₅ 71267 65-75 Na ₂ O 6388 6-10 La ₂ O ₃ 10669 8-12 allocations: NiO 0:01 to 12:05 a.m. MnO ₂ 0.01-0.2 Sm ₂ O ₃ 0:01 to 12:05 a.m. Cr ₂ O ₃ 0:01 to 12:05 a.m. Additional allocations: Y, Yb, Eu, Tm, Tb 0.01-0.2 as trivalent fluorides Photovoltaic module according to one of the claims 1 to 4, characterized in that the photovoltaic module further includes a cover glass with UV blocking. Photovoltaic module according to claim 5, characterized in that the cover glass contains TiO ₂ in a proportion of 0.05-0.5 wt .-%, based on the total amount of the cover glass. Photovoltaic module according to one of the claims 1 to 6, characterized in that the water content is less than 40 mmol / l. Photovoltaic module according to one of claims 1 to 7, characterized in that nanocrystals having a size of less than 200 nm, in particular less than 50 nm, preferably less than 30 nm, especially preferably less than 10 nm are contained.