RU2531768C1 - Double-sided solar photoconverter (versions) - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the field of solar photovoltaic energetics, namely, to devices for direct conversion of solar energy into electric one. There are two versions proposed for a double-sided solar photoconverter (PC), comprising two identical solar elements (SE) on the basis of sensitised metal-oxide (MO) mesostructures, the illuminated surfaces of which are aligned in opposite directions. In the first version of the PC both SE are mounted on a common conducting rear contact from a flexible metal base with a conducting coating applied on its both surfaces, and upper conducting contacts represent flexible polymer transparent films with a conducting transparent coating applied onto them. In the second version of the invention both SE are mounted on a common conducting rear contact from a glass plate with a conducting coating applied on its both surfaces, and upper conducting contacts represent glass plates with a conducting transparent coating applied onto them. Sensitised MO mesostructures are applied onto the conducting transparent coating on polymer transparent films (version 1) or onto the conducting transparent coating on glass plates, used as the upper conducting contacts (version 2). As the sensitised MO mesostructures for both identical SE they use sensitised nanocrystalline metal oxides selected from the group: titanium dioxide, zinc oxide, nickel oxide, iron oxide or their mixtures.

EFFECT: proposed PC provides for direct conversion of light energy into electric one with the high efficiency both at high intensity of emission (AM1,5, 1000 W/m²), and at low and diffused illumination, also inside a room (with intensity within 10-100 W/m²).

14 cl, 3 dwg

Description

The invention relates to the field of solar photovoltaics, and in particular to devices for the direct conversion of solar energy into electrical energy based on sensitized metal-oxide solar cells. Most successfully, the present invention can be applied in free-standing small and medium-sized solar photoconverters to generate electricity in low and diffuse low-intensity lighting conditions, in particular indoors.

In the last decade, a huge rapidly growing industry for the production of solar panels has formed in the world, which shows an annual increase of ~ 40%. So, the capacity of solar panels produced in 2011 in the world exceeded 20 GW, and the annual turnover of funds associated with the research, production and development of the infrastructure of solar cells and panels amounted to about 100 billion US dollars. The development of solar energy requires continuous improvement of the parameters of photoconverters and solar cells (SC). Along with the development of solar photovoltaics, oriented to work with intense light flows in open space (outdoor conditions), in recent years, an important direction has been the adaptation of solar cells to work in low light: in shading and in diffuse lighting, in particular indoors, where the prevailing spectrum of reflected light (indoor conditions).

The efficiency of solar cells in standard direct sunlight (illumination intensity AM 1.5 or 1000 W / m ² ) is determined by specially selected parameters that do not coincide with the characteristics of solar cells oriented to work in low and diffuse light conditions (10-100 W / m ² ) It should be noted that in real conditions, in which the photoconverter (FP) is located most of the time, located at the latitude of central or northern Europe or central Russia, low and even diffuse illumination prevails. Traditional solar cells based on crystalline or amorphous silicon have proven themselves to work in high light conditions, as well as in the atmospheric sun (under AM0 illumination). However, due to its structural and structural features, the efficiency (Efficiency) of silicon elements at low or diffuse illumination significantly decreases (by 50-60% at an illumination of 10 W / m ² ).

SC of the so-called 3rd generation based on sensitized metal oxide (MO) mesostructures in recent years have been of increasing interest due to their peculiarity to utilize solar energy with almost constant efficiency regardless of the light intensity in the range of 10-1000 W / m ² , as well as regardless of the angle of incidence of light, that is, under diffuse illumination conditions, while the light conversion efficiency reaches 12%, which exceeds the efficiency of thin-film SCs based on amorphous silicon (~ 6-7%) and is not inferior to awns micromorph solar cells based on silicon.

Known SC based on sensitized nanocrystalline titanium dioxide (US patent No. 4927721, publ. 05.22.1990), designed to generate electricity in direct sunlight, which consists of a nanocrystalline titanium dioxide layer with a thickness of about 10 μm, sensitized by dye molecules that absorb light radiation in the range of 400-700 nm. Depending on the type of sensitizer used, the efficiency of converting solar energy into electrical energy varies from 5 to 12%.

The disadvantage of this known sensitized MO SE is its use only in direct sunlight and the absence of any data on its ability to utilize light in diffuse lighting conditions. In addition, with an increase in the area of the light-receiving surface of a given solar cell, the sequential resistance of the transparent contact unacceptably increases, which is reflected in a deterioration in the type of current-voltage characteristic, a decrease in the short-circuit current and the filling factor - as a result, the efficiency of the solar cells decreases.

Known tandem MO FP (US application No. 20070062576, publ. March 22, 2007) for generating electricity in direct sunlight, which consists of two sensitized MO SEs located one below the other, including two different sensitizers: TCPP-Pd and TCPP-Zn. The upper one (sensitized with TCPP-Pd dye) absorbs and utilizes a part of the solar spectrum with an emission intensity of AM1.5 (1000 W / m ² ) in the spectral range of 400 - 600 nm and passes the remaining part of the light to the lower SC, which utilizes and converts into electricity the remainder of the spectrum in the range of 400-850 nm.

The main disadvantage of this well-known tandem AF is that it uses only the direct flux of photons to generate electricity, which does not allow using the full potential of light radiation. A disadvantage is also the low efficiency of converting light flux into electricity by the lower MO SE (utilizing the part of direct solar radiation remaining after passing through the upper SE). The low open circuit voltage of the lower SC, the value of which is inferior to the open circuit voltage of the upper SC, leads to the uncompensation of the electrical characteristics of this tandem FP both in parallel and in series connection of two tandem components. The latter leads to the loss of a significant part of the radiation useful for the upper SC (due to the use of the conversion layers of the upper and lower SC not optimized in thickness and spectral characteristics). As a result, the additional efficiency of using the tandem structure is low and adds less than 10% of the total efficiency of the tandem AF to the efficiency of the upper SC. The total efficiency of this tandem AF does not exceed 12.5% when lighting AM1.5 (1000 W / m ² ), which differs little from the efficiency of the best MO solar cells of a standard (non-tandem) type for such light intensity.

Until recently, all known AFs were one-sided - SCs in them receive light only on one side and only a direct photon flux, which, in principle, does not allow to fully use the potential of light radiation and to use such AFs in low light conditions and in diffuse lighting particular indoor.

Only recently appeared voluminous solar cells (in contrast to conventional flat ones) containing bilateral silicon solar cells, see, for example, RU 2446363, publ. 03/27/2012. Bilateral solar AFs based on MO of sensitized structures are currently unknown.

In said patent RU 2446363 a solar battery is proposed in which silicon solar cells are located inside the hollow volume of the battery and are double-sided. Luminous flux of direct solar radiation is directed into the interior of the hollow volume of the battery, guide mirrors are installed on the side surfaces of the solar battery, which direct the incident sunlight on them inside the battery, in addition, translucent mirrors or films are installed on the side surfaces and the bases of the solar battery forming a closed volume. The internal space of a volumetric solar battery is filled with air (gas), which is used both for the dissipation of solar energy and for cooling the solar cell elements to the optimum temperature of their functioning.

This volumetric solar battery will allow to receive a greater amount of electric energy compared to flat ones with the same occupied surface area, however, like other known ones, it is designed to operate in conditions of high-intensity direct sunlight, which is directed into the internal volume of the battery, which eliminates the ability to operate the system in low and diffuse lighting conditions. In addition, the battery has a complicated design.

Of great interest is the creation of new types of bilateral solar AFs based on sensitized MO solar cells, which are specially oriented to work in conditions of low light intensity and in diffuse lighting conditions, in particular indoors.

The objective of the invention is the development of a two-sided solar AF (options), consisting of SC based on sensitized MO mesostructures, which will increase the efficiency of conversion of light energy into electrical energy both at high radiation intensity (AM1.5, 1000 W / m ² ), and at low and diffuse illumination, including indoors (with an intensity in the range of 10-100 W / m ² ). The inventive FP should also differ in a fairly simple design.

The solution to this problem is achieved by the proposed:

- a two-sided solar photoconverter containing two identical solar cells based on sensitized metal oxide mesostructures, the illuminated surfaces of which are oriented in opposite directions, while both solar cells are mounted on a common conductive rear contact made of a flexible metal base with a conductive coating deposited on both surfaces, and the upper conductive contacts are flexible polymer transparent films with a conductive transparent coating applied to them eat.

Sensitized metal-oxide mesostructures are deposited on a conductive transparent coating on polymer transparent films.

As sensitized metal oxide mesostructures for both identical solar cells, sensitized nanocrystalline metal oxides selected from the group: titanium dioxide, zinc oxide, nickel oxide, iron oxide, or mixtures thereof can be used.

As sensitized metal oxide mesostructures for both identical solar cells, sensitized mesostructures of titanium dioxide 5-15 μm thick consisting of titanium dioxide nanoparticles of an average size of 10-100 nm can be used.

Titanium dioxide can be sensitized with an organic dye.

The common conductive back contact can be made of metal foil with a platinum layer 20-30 nm thick or a layer of carbon nanotubes 30-300 nm thick deposited on both its surfaces.

The conductive transparent coating on polymer transparent films can be made of tin oxide doped with fluorine or indium.

- a two-sided solar photoconverter containing two identical solar cells based on sensitized metal-oxide mesostructures, the illuminated surfaces of which are oriented in opposite directions, while both solar cells are mounted on a common conductive rear contact from a glass plate with a conductive coating applied to both surfaces, and the upper conductive contacts are glass plates coated with a conductive transparent coating.

Sensitized metal oxide mesostructures are deposited on a transparent conductive coating on glass plates used as upper conductive contacts.

As sensitized metal oxide mesostructures for both identical solar cells, sensitized nanocrystalline metal oxides selected from the group: titanium dioxide, zinc oxide, nickel oxide, iron oxide, or mixtures thereof can be used.

As sensitized metal oxide mesostructures for both identical solar cells, sensitized mesostructures of titanium dioxide 5-15 μm thick consisting of titanium dioxide nanoparticles of average size 10-100 nm can be used.

Titanium dioxide can be sensitized with an organic dye.

A conductive coating applied to both surfaces of a glass plate used as a common conductive back contact can be made of a platinum layer 20-30 nm thick or a layer of carbon nanotubes 30-300 nm thick.

The conductive transparent coating on glass plates used as top conductive contacts may be made of tin oxide doped with fluorine or indium.

Mesostructures layer thickness of titanium dioxide or other MO, MO nanocrystals size and technology of mesostructures selected so as to ensure effective operation of the proposed OP (embodiment) as in a high radiation intensity (AM1.5, 1000 W / m ²⁾ and at a low and diffuse illumination, in particular indoors, where the intensity of the light flux is in the range of 10-100 W / m ² .

Figure 1 presents a block diagram for two variants of the inventive two-sided solar AF - the first option is mounted on a flexible conductive base, the second on glass conductive substrates.

In the proposed two-sided solar FP (options), there is an identical design on both sides of two solar cells oriented in opposite directions. Light falls on both SCs either through flexible transparent polymer films 1 (option 1) or through glass substrates 1 (option 2), while both films and glass substrates are coated with a transparent conductive layer of tin oxide 2 doped with fluorine (FTO: fluoride tin oxide) or indium (ITO: indium tin oxide), and are the upper conductive contacts. Then, the light enters the mesostructure layer of metal oxide 3 sensitized with an organic dye deposited on a transparent conductive layer of the upper conductive contacts. Both identical SCs are mounted on a common rear carrier contact 4, either made of metal foil coated on both sides with a thin conductive layer 5 of platinum or carbon nanotubes (option 1), or in the form of a glass substrate coated on both sides with a thin conductive layer 5 of platinum or carbon nanotubes (option 2). The layer of sensitized mesostructures of metal oxide 3 is adjacent to the conductive layers 5 of the common rear bearing contact 4.

Example.

The functioning of the proposed two-sided solar AF was tested on a manufactured laboratory sample consisting of two identical MO solar cells mounted on a common rear contact. In each SC, the upper transparent contact was made of a polymer film transparent in the visible spectral region, coated on the side of the SC volume with a conductive layer of tin oxide doped with fluorine (FTO), 30 nm thick with a conductivity of 10 Ohm · cm. An MO layer of mesostructures consisting of titanium dioxide (TiO ₂ ) nanoparticles with a size of 20-30 nm and a thickness of about 10 μm was formed on the surface of the conductive layer. In the mesoscopic layer, individual TU2 nanoparticles were in electrical contact with each other and formed a porous structure with pore sizes of about 20 nm. The surface of the mesoporous structure was covered with a monolayer of molecules of the sensitizer N719 (DYESOL, Australia), absorbing light radiation in the range 400-700 nm. The space of the mesolayer was filled with an iodine-containing electrolyte, the mesoporous layer of both SCs adjoined the common back contact of the FP made of a flexible metal foil (aluminum), the surface of which was coated on both sides with a sprayed conductive layer of platinum with a thickness of 20 nm.

When illuminating the surfaces of FEs of a two-sided phase transition in the volume of the MO layer of mesostructures, the process involves the capture of light quanta by sensitizer molecules, electron transfer from the ground to the excited state of the sensitizer molecule, and, as the next stage, electron transfer from the sensitizer molecule to the conduction band of titanium dioxide. Next, diffusion electron transfer occurs through the bulk of the mesolayer to the upper contacts of the solar cells. The role of the electrolyte in the volume of the mesoporous structure is to replenish the charge carriers in the dye molecules through a redox pair from the back contact of the SC made of platinum. The load is connected via the upper and lower conductive contacts. The proposed two-sided solar AF has shown high efficiency in converting solar energy into electrical energy at high and low light intensities.

Figure 2 shows the volt-ampere (VA) characteristic of the proposed two-sided MO FP 1 cm ² when it is illuminated on both sides by light with an intensity of 50 W / m ² . The BA characteristic shown shows how the photocurrent density for each of the two SCs of a two-sided phase varies depending on the applied voltage. The BA characteristic is also given for the total photocurrent density from both SCs of a two-sided phase transition. The data obtained allow us to calculate the efficiency (efficiency) of the proposed FP - one of the most important indicators of the FP, characterizing the efficiency of light conversion, which is determined by the ratio of the electric power received from the FP to the power of the light radiation incident on its SC and expressed in%. The efficiency of the proposed two-way AF, when each side is illuminated with light with an intensity of 50 W / m ² , is 4.2%. The parameters of the presented BA characteristic indicate that the proposed two-sided phase transition shows a high photocurrent density in low light conditions, that is, under conditions in which other known types of phase transition density significantly decrease, resulting in a proportional decrease in efficiency. The VA characteristic was obtained under conditions simulating the two-sided illumination of MO solar cells with an intensity of 50 W / m, which corresponds to the diffuse illumination regime mainly by reflected light indoors. The relatively high values of the obtained VA characteristics indicate the prospects of using the proposed two-sided MO FP for indoor use.

Silicon-based solar cells have high solar energy conversion efficiency only under direct light exposure and high illumination intensities - not lower than 1000 W / m ² . With decreasing illumination, the efficiency of silicon phase transitions decreases sharply. Figure 3 presents comparative data that demonstrate the degree of decrease in efficiency with a decrease in the intensity of illumination for silicon FP and for the proposed MO FP. The presented dependences clearly demonstrate the advantages of MO solar cells as compared to silicon solar cells under the operation of phase transitions in low light conditions. So, in low light conditions with an intensity of 10 W / m ^{2, the} relative efficiency of the proposed MO FP is almost 2 times higher than the efficiency of a silicon-based FP.

Thus, the proposed two-sided solar AF (options) based on sensitized MO SC provides direct conversion of light energy into electrical energy with high efficiency both at high radiation intensity (AM1.5, 1000 W / m ² ), and at low and diffuse illumination, including indoors (with an intensity in the range of 10-100 W / m ² ), and has a fairly simple design.

Claims (14)

1. A two-sided solar photoconverter containing two identical solar cells based on sensitized metal-oxide mesostructures, the illuminated surfaces of which are oriented in opposite directions, while both solar cells are mounted on a common conductive rear contact made of a flexible metal base with a conductive coating applied to both of its surfaces and the upper conductive contacts are flexible polymer transparent films with a conductive transparent coating applied to them m. 2. The two-sided solar photoconverter according to claim 1, characterized in that the sensitized metal oxide mesostructures are deposited on a conductive transparent coating on polymer transparent films. 3. The two-sided solar photoconverter according to claim 1, characterized in that sensitized nanocrystalline metal oxides selected from the group are used as sensitized metal oxide mesostructures for both identical solar cells: titanium dioxide, zinc oxide, nickel oxide, iron oxide or their mixtures. 4. The two-sided solar photoconverter according to claim 1, characterized in that as sensitized metal oxide mesostructures for both identical solar cells, sensitized mesostructures of titanium dioxide 5-15 microns thick, consisting of titanium dioxide nanoparticles of an average size of 10-100 nm, are used. 5. A two-sided solar photo converter according to claim 4, characterized in that the titanium dioxide is sensitized by an organic dye. 6. The two-sided solar photoconverter according to claim 1, characterized in that the common conductive back contact is made of metal foil with a platinum layer 20-30 nm thick or a layer of carbon nanotubes 30-300 nm thick deposited on both its surfaces. 7. The two-sided solar photoconverter according to claim 1, characterized in that the conductive transparent coating on polymer transparent films is made of tin oxide doped with fluorine or indium. 8. A two-sided solar photoconverter containing two identical solar cells based on sensitized metal-oxide mesostructures, the illuminated surfaces of which are oriented in opposite directions, while both solar cells are mounted on a common conductive rear contact from a glass plate with a conductive coating applied to both of its surfaces and the upper conductive contacts are glass plates coated with a conductive transparent coating. 9. The two-sided solar photoconverter according to claim 8, characterized in that the sensitized metal oxide mesostructures are deposited on a conductive transparent coating on glass plates used as upper conductive contacts. 10. The two-sided solar photoconverter according to claim 8, characterized in that as sensitized metal oxide mesostructures for both identical solar cells, sensitized nanocrystalline metal oxides selected from the group are used: titanium dioxide, zinc oxide, nickel oxide, iron oxide or their mixtures. 11. A two-sided solar photoconverter according to claim 8, characterized in that sensitized mesostructures of titanium dioxide 5-15 μm thick consisting of titanium dioxide nanoparticles of average size 10-100 nm are used as sensitized metal oxide mesostructures for both identical solar cells. 12. Two-sided solar photoconverter according to claim 11, characterized in that the titanium dioxide is sensitized by an organic dye. 13. A two-sided solar photoconverter according to claim 8, characterized in that the conductive coating deposited on both surfaces of the glass plate used as a common conductive back contact is made of a platinum layer 20-30 nm thick or a carbon nanotube layer 30-300 nm thick . 14. Two-sided solar photoconverter according to claim 8, characterized in that the conductive transparent coating on glass plates used as upper conductive contacts is made of tin oxide doped with fluorine or indium.

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