RU2792023C1 - Dye-sensitized solar cell unit, a photovoltaic charger including a dye-sensitized solar cell unit, and a method for manufacturing a solar cell unit - Google Patents

Abstract

FIELD: power sources.

SUBSTANCE: invention relates to a unit of a dye-sensitized solar cell, a photovoltaic charger. The unit (1) of a dye-sensitized solar cell contains: a working electrode containing a porous light-absorbing layer (10), a porous first conductive layer (12), including a conductive material for extracting photogenerated electrons from the light-absorbing layer (10), a porous insulating layer (105), a counter electrode containing a porous catalytic conductive layer (106), formed on the opposite side of the porous insulating layer (105), an ionic electrolyte for the transfer of electrons from the counter electrode to the working electrode, moreover, the first conductive layer (12) contains an insulating oxide layer (109) formed on the surfaces of the conductive material, and the porous catalytic conductive layer (106) contains a conductive material (107’) and catalytic particles (107’’) distributed in the conductive material.

EFFECT: high long-term stability of performance characteristics, an increase in the efficiency of the solar cell unit, the ability to work in a wide temperature range.

16 cl, 10 dwg, 2 tbl

Description

Technical field

The present invention relates to a dye-sensitized solar cell assembly. The present invention further relates to a photovoltaic charger specially adapted for charging an electronic device including a dye sensitized solar cell unit.

PREREQUISITES FOR CREATING

Solar cells have been used for a long time to convert light energy into electricity. Solar panels are used to absorb sunlight as an energy source to generate electricity. The solar panel contains multiple solar cells connected in series. Solar panels in large quantities are often bundled together in large solar complexes to produce electricity for the power grid.

Solar cells are becoming more efficient and also cheaper to produce. So, naturally, companies are creating all kinds of consumer products powered at least in part by solar cells. Many portable electronic devices are currently provided with built-in rechargeable batteries that store energy and photovoltaic chargers that are configured to supply power to the batteries to charge them. A photovoltaic charger or solar charger uses solar energy to supply electricity to devices and to charge batteries. Examples of such portable devices are tablets, mobile phones, headphones and calculators. When solar cells are used, the device's battery is packaged so that the usage time is increased before it becomes necessary to charge the device from an external source. Depending on the efficiency of the photovoltaic charger and the power consumption of the device, it may even be unnecessary to charge the device with an external source, and the device is then powered only by solar energy. For example, miniature calculators are often powered solely by photovoltaic chargers.

Photovoltaic chargers on the market today use various types of solar panels, from thin-film panels with efficiencies (COPs) of 7-15% to slightly more efficient monocrystalline panels that provide up to 18% efficiency. Efficiency is usually tested using Standard Test Conditions, STC, which is the industry standard for the conditions under which solar panels are tested. In the case of STC, the exposure is 1000 W/m², the temperature is 25°C and the air mass is 1.5. As an example, a solar panel giving an output power of 200 W/m² has an efficiency of 20%. These conditions simulate the efficiency of a solar panel under external conditions on a cloudless summer sunny day. The wavelength spectrum of indoor light illumination (indoors) is different from the wavelength spectrum of external light radiation (outdoors). For example, non-visible wavelengths are often absent from indoor lighting because glass windows filter UV light and indoor lamps primarily produce light in the visible range. Thus, solar panel efficiency measured in outdoor conditions cannot be applied to indoor conditions. The normal human eye will respond to wavelengths between about 390 and 700 nm, and indoor light is mostly within the visible light spectrum.

In "Comparison of the indoor performance of 12 commercial PV products by a simple model", Georgia Apostolou et al. (George Apostolou and others) explains how internal light illumination differs from external light radiation. The author of the article claims that in the case of a double-glazed window, the reduction in radiation power at 1 and 5 m from the window will be about 70% and 97%, respectively. The article shows that currently solar panels are losing most of their efficiency in indoor lighting. Thus, the disadvantage of these solar panels is that they have a low efficiency at low light intensities (light emission).

Other disadvantages of existing solar cell panels for powering electronic devices are that some of them are toxic, have poor mechanical properties and are expensive.

In GB2510451(A) OnBeat Ltd. a pair of solar-powered headphones is shown. A flexible solar panel is provided on the outer surface of the headband and on the earcups. The headphones can also be used to power an external device with stored solar energy. It is visually obvious to an observer that the OnBeat headband is covered with a solar cell panel, but the type of solar cell is not specified.

The need for solar panels to power consumer products is very different compared to stationary solar panels used to generate electricity in large solar complexes. For example, a solar panel in a consumer product needs to be stronger, more flexible, and able to withstand impact. Additionally, they must be able to generate power under different lighting conditions, both indoors and outdoors. The lighting conditions on different parts of the solar panel may also differ due to the partial shading of the solar panel, which reduces the efficiency of the solar panel. It is also desirable that the solar panels be aesthetically pleasing as long as they are visible to the user.

It should be noted that there are many examples of photovoltaic chargers having a solar panel including a plurality of solar cells connected in series to power portable electronic devices. However, there are several problems with known solar panels that power portable electronic devices: they are very sensitive to light intensity and incident light angle. A solar panel with solar cells connected in series is sensitive to partial shading because if one solar cell fails to produce current, the entire string of solar cells will stop producing electricity. They are very sensitive and break easily. For example, crystalline silicon solar cells are brittle and may crack when used on a portable electronic device. Moreover, users may not be satisfied with the aesthetics when large parts of the product are covered with solar panels having a grid of visible down conductors on the top side. Thus, there is a need to improve photovoltaic chargers for use with portable electronic devices.

WO2013/149787 discloses a dye-sensitized solar cell module having a serial structure comprising a plurality of dye-sensitized solar cell stacks adjacent to each other and connected in series. Each cell block includes a working electrode, a first conductive layer for extracting photogenerated electrons from the working electrode, a counter electrode including a second conductive layer, an electrolyte for transferring electrons from the counter electrode to the working electrode, and a series connection element for electrically connecting the counter electrode to the adjacent working electrode. element block. The solar cell module comprises a porous insulating substrate, the first conductive layer is a porous conductive layer formed on one side of the porous insulating substrate, and the second conductive layer is a porous conductive layer formed on the opposite side of the porous insulating substrate, and the series connection element is a conductive a layer penetrating the porous insulating substrate and extending between the first conductive layer of one of the cell blocks and the second conductive layer of the adjacent cell block, thereby electrically connecting the first conductive layer of one of the cell blocks to the second conductive layer of the adjacent cell block.

WO2014/184379 discloses a dye-sensitized solar cell having conductive particles forming a conductive mesh through an insulating material in a porous insulating substrate. The particles form one or more electrically conductive paths through the insulating material of the insulating substrate. The conductive particles may also be catalytic. Thanks to the conductive mesh in the insulating substrate, the distance between the counter electrode and the light absorbing layer is no longer dependent on the thickness of the porous substrate. Thus, the thickness of the insulating portion can be reduced, and thereby the distance between the counter electrode and the light absorbing layer can be reduced. Accordingly, the resistance losses in the conductive medium are reduced. Due to the fact that the distance between the counter electrode and the light absorbing layer no longer depends on the thickness of the entire porous substrate, but only on the insulating part, it is also possible to use a substrate that is thick enough for safe machining.

Brief description of the essence of the invention

It is an object of the present invention to at least partially overcome the problems described above and to provide an improved dye sensitized solar cell and photovoltaic charger suitable for charging electronic devices for consumer applications, and more particularly for charging rechargeable batteries in electronic devices.

This goal is achieved using a dye-sensitized solar cell, as defined in paragraph 1 of the claims.

The block of the dye-sensitized solar cell contains:

- a working electrode containing a porous light-absorbing layer,

a porous first conductive layer including a conductive material for extracting photogenerated electrons from the light absorbing layer, wherein the light absorbing layer is located on top of the first conductive layer,

a porous insulating layer made of an insulating material, wherein the first conductive layer is formed on one side of the porous insulating layer,

a counter electrode comprising a porous catalytic conductive layer formed on the opposite side of the porous insulating layer, and

- an ionic electrolyte for electron transfer from the counter electrode to the working electrode and located in the pores of the porous first conductive layer, the porous catalytic conductive layer and the porous insulating layer, the first conductive layer contains an insulating oxide layer formed on the surfaces of the conductive material, and the porous catalytic conductive layer contains a conductive material and catalytic particles dispersed in the conductive material to improve the transfer of electrons from the conductive material to the electrolyte.

By ionic electrolyte is meant an electrolyte containing ions as a carrier for electrons. An advantage of using an ionic electrolyte is that it can provide high long-term stability to the performance of the solar cell. Another advantage is that the efficiency of the solar cell stack is stable or increases with increasing temperature. Accordingly, the solar cell stack performs well over a wide temperature range.

The electrolyte is located in the pores of the light-absorbing layer, the first conductive layer, the catalytic conductive layer, and the porous insulating layer. The electrolyte contains ions that transport electrons from the counter electrode to the light-absorbing layer of the working electrode. The insulating oxide layer provides an electrically insulating layer on the conductive material of the first conductive layer, the oxide layer at least partially preventing the transfer of electrons between the conductive material and the electrolyte located in the pores of the first conductive layer. Accordingly, more electrons reach the light-absorbing layer, thereby increasing the efficiency of the solar cell unit.

The catalytic particles are made of a material that is different from the conductive material of the catalytic conductive layer. The catalytic particles act as catalysts and facilitate the transfer of electrons from the conductive material to the electrolyte in the pores of the catalytic conductive layer. The conductive material of the catalytic conductive layer is essentially non-catalytic, ie. at most, only minor catalytic reactions can take place in the conductive material. Electrons are extracted by ions in the electrolyte in the catalytic conductive layer. By distributing the catalytic particles in the conductive material, the transfer of electrons from the conductive material is improved, and accordingly the efficiency of the solar cell unit is improved. Additionally, due to the location of the catalytic particles as close as possible to the working electrode, the distance that the ions in the electrolyte must travel in order to reach the working electrode is reduced. Thus, the effective distance between the working electrode and the counter electrode is reduced, and the resistance loss in the electrolyte is correspondingly reduced, resulting in a higher efficiency of the solar cell unit. An additional advantage achieved with reduced spacing is that it allows the use of conductive media having low electrical conductivity, such as ionic liquid electrolytes.

The combination of an insulating oxide layer that prevents electrons from the conductive material from leaking into the electrolyte in the pores of the first conductive layer and a counter electrode containing a catalytic conductive layer containing catalytic particles dispersed in the conductive material improves electron transfer to the electrolyte in the counter electrode, resulting in an efficient block solar element.

Additionally, during the manufacture of the solar cell block, heat treatment of the solar cell block in air will result in an oxide layer on the conductive material of the first conductive layer as well as on the conductive material of the catalytic conductive layer. It can be assumed that the oxide layer on the conductive material of the catalytic conductive layer will prevent the transfer of electrons from the conductive material to the electrolyte located in the pores of the catalytic conductive layer. Surprisingly, it has been found that catalytic particles, such as platinized carbon particles, dispersed in the conductive material allow electrons to be transferred from the conductive material to the electrolyte despite oxide layers on the conductive material.

The catalytic conductive layer is conductive as well as catalytic. The electrolyte can be located in the pores of the entire catalytic conductive layer or only in the upper part of the catalytic conductive layer.

In one aspect, the counter electrode comprises a second conductive layer including a conductive material in electrical contact with the catalytic conductive layer, wherein the second conductive layer is substantially non-catalytic and the porous catalytic conductive layer is interposed between the porous insulating layer and the second conductive layer.

In this aspect, the dye-sensitized solar cell assembly comprises:

- a working electrode containing a porous light-absorbing layer,

- a first conductive layer containing a conductive material for extracting photogenerated electrons from the light absorbing layer, the light absorbing layer being located on top of the first conductive layer,

a porous insulating layer made of an insulating material, wherein the first conductive layer is formed on one side of the porous insulating layer,

- a counter electrode containing:

i. a second conductive layer including a conductive material, and

ii. a porous catalytic conductive layer located between the porous insulating layer and the second conductive layer and in electrical contact with the second conductive layer, and

- an ionic electrolyte located in the pores of the first conductive layer, the catalytic conductive layer and the porous insulating layer for electron transfer from the counter electrode to the working electrode, wherein the first conductive layer contains an insulating oxide layer formed on the surfaces of the conductive material, the second conductive layer is essentially non-catalytic, and the catalytic conductive layer comprises a conductive material and catalytic particles dispersed in the conductive material to improve electron transfer to the electrolyte.

The second conductive layer is made of a conductive material. The second conductive layer may be porous or non-porous. Preferably, the second conductive layer excludes catalytic particles. The second conductive layer is itself essentially non-catalytic, ie. at most, only minor catalytic reactions can take place in the second conductive layer. The second conductive layer may contain a minor amount of catalytic material. However, the catalytic reactions are concentrated in the catalytic conductive layer. The electrons are preferably transferred to the electrolyte in the catalytic conductive layer due to its shorter distance to the working electrode.

Due to the fact that the second conductive layer is essentially non-catalytic, the electrical conductivity of the second conductive layer may be higher than the electrical conductivity of the catalytic conductive layer. Thus, the combination of a catalytic conductive layer including catalytic particles and a second conductive layer that is substantially non-catalytic will result in an efficient transfer of electrons from the counter electrode to the electrolyte as well as high electrical conductivity of the counter electrode. Additionally, due to the fact that the second conductive layer is substantially non-catalytic, it is more difficult for electrons to be transferred to the electrolyte in the second conductive layer.

When the solar cell stack is used, the second conductive layer receives electrons from the external circuit and distributes the electrons over the catalytic conductive layer. The catalytic particles act as catalysts and facilitate the transfer of electrons received from the second conductive layer to the electrolyte in the pores of the catalytic conductive layer. By positioning the catalytic particles as close as possible to the working electrode, the distance that the ions have to travel in the electrolyte to reach the working electrode is reduced. Accordingly, the power loss in the solar cell unit is reduced, and thus the efficiency of the solar cell unit is further improved. The second conductive layer ensures efficient distribution of electrons across the catalytic conductive layer.

In particular, the combination of an insulating oxide layer that prevents electrons from leaking from the conductive material into the electrolyte in the pores of the first conductive layer and a counter electrode comprising a catalytic conductive layer and a non-catalytic second conductive layer that improves the efficiency of the counter electrode will result in an efficient solar cell package that is capable of generate power in a wide range of different lighting conditions. The solar cell unit operates in both poor and excellent light conditions, such as indoors under artificial light and outdoors in shade and strong sunlight.

In one aspect, the conductive material of the second conductive layer is titanium or an alloy thereof. In one aspect, the first and second conductive layers comprise titanium or an alloy thereof. It is preferable to use titanium because it is highly corrosion resistant and can withstand high temperatures, which is advantageous in the manufacture of a solar cell stack.

The catalytic particles are made of a catalytic material, for example, carbon-based materials such as graphene or graphite, or carbon black, or carbon nanotubes, platinum, or combinations thereof. Catalytic particles can be electrically conductive as well as catalytic. In one aspect, the electrical conductivity of the catalyst particles is lower than the conductivity of the second conductive layer.

For example, the electrolyte is an ionic liquid electrolyte.

In one aspect, the catalyst particles are substantially evenly distributed in the catalytic conductive layer. The term "substantially evenly distributed" means that the catalyst particles are distributed over the entire area of the catalytic conductive layer. Thus, the catalyst particles are not concentrated in only one or a few parts of the catalytic conductive layer. Although the concentration of catalytic particles may vary across the area of the catalytic conductive layer, there are no large areas without any catalytic particles. Electrolyte filled the pores of the porous catalytic conductive layer. By distributing the catalytic particles substantially uniformly in the catalytic conductive layer, the transfer of electrons from the conductive material of the catalytic conductive layer to the electrolyte is achieved over the entire area of the catalytic conductive layer, and accordingly the electron transfer from the conductive particles to the electrolyte is improved.

In one aspect, the conductive material of the porous catalytic conductive layer forms a porous matrix and the catalyst particles are distributed in the porous matrix. By porous matrix is meant a porous layer including a network of interconnected conductive particles that form conductive paths through the porous layer. Preferably, the catalyst particles are substantially evenly distributed in the porous matrix. The catalytic particles are embedded in a porous matrix. For example, the porous matrix is a layer of sintered conductive particles, and the catalytic particles are located between the conductive particles. The porous matrix encloses the catalytic particles and holds them in place. The porous matrix can act as a glue between the catalyst particles and hold them in place.

In one aspect, the conductive material of the first conductive layer is porous titanium and the insulating oxide layer is titanium oxide formed on the surfaces of the porous titanium. The first conductive layer comprises a titanium oxide layer formed on the surfaces of the porous titanium and covering the surfaces of the porous titanium. The titanium oxide layer prevents the leakage of electrons from the porous titanium in the first conductive layer into the electrolyte in the pores of the first conductive layer and accordingly increases the efficiency of the solar cell unit. In one aspect, the porous titanium contains sintered titanium particles, and the surfaces of the sintered titanium particles are coated with a layer of titanium oxide.

In one aspect, the catalytic conductive layer contains from 1 to 50 wt.% catalytic particles. The wt % (wt %) of catalyst particles required to achieve efficient electron transfer from the conductive material to the electrolyte depends on the size and shape of the catalyst particles and the type of material in the catalyst particles and the type of conductive material.

In another aspect, the catalytic conductive layer contains from 1 to 30 wt.% catalytic particles. This range is, for example, suitable when the conductive particles are made up of titanium and the catalytic particles are made up of platinized carbon. However, as mentioned earlier, the wt.% of the catalytic particles depends on the size of the particles.

In one aspect, the catalytic conductive layer contains at least 1 wt.% catalytic particles. In one aspect, the catalytic conductive layer contains at least 5 wt.% catalytic particles. In one aspect, the catalytic conductive layer contains at least 10 wt.% catalytic particles.

In one aspect, the catalytic conductive layer contains more than 50% by weight of conductive material and less than 50% by weight of catalyst particles.

The term "NN wt.%" means that the particles represent NN% of the total mass of conductive and catalytic particles. The actual weight % of the catalytic/conductive particles depends on the difference in size between the catalytic and conductive particles and the type of material in the catalytic and conductive particles.

The conductive material of the catalytic conductive layer is, for example, a metal, a metal alloy, a metal oxide or other conductive materials such as titanium, titanium alloys, nickel or nickel alloys, indium or indium oxide.

In one aspect, the conductive material of the catalytic conductive layer is titanium. For example, the conductive material of the catalytic conductive layer contains sintered titanium particles.

In one aspect, the catalyst particles contain carbon. Carbon is a catalytic substance. Carbon is inexpensive and environmentally friendly.

In one aspect, the catalyst particles comprise platinized carbon particles. Platinum is a better catalyst than carbon, but it is more expensive. By using a combination of platinum and carbon, a good catalyst is provided at a lower cost.

In one aspect, the conductive material of the catalytic conductive layer is titanium and the catalyst particles are platinized carbon particles. The term "platinized carbon particles" refers to particles having a backbone of carbon coated with a layer of platinum. Platinum is a good catalyst. However, the problem with platinum is that it is difficult to attach it to titanium. Platinum can be easily attached to carbon. However, the problem with carbon is that it has poor mechanical strength. These problems are solved by distributing platinized carbon particles in a titanium matrix. Titanium has good mechanical strength and keeps the platinized carbon particles in their positions in the catalytic conductive layer. Thus, carbon, platinum and titanium together provide a catalytic conductive layer with high mechanical strength and high electron transfer capacity in the electrolyte.

In one aspect, the catalytic conductive layer contains from 50 to 90 wt.% titanium. In one aspect, the catalytic conductive layer contains at least 5 wt.% carbon and preferably at least 10 wt.% carbon. In one aspect, the catalytic conductive layer contains at least 0.001 wt.% platinum.

In one aspect, the catalytic conductive layer comprises a mixture of conductive particles and catalytic particles. The conductive particles are in electrical contact with the second conductive layer. The catalytic particles are mixed with the conductive particles to improve the transfer of electrons from the conductive particles to the electrolyte. The conductive particles are made of a conductive material. Preferably, the conductive particles are non-catalytic and exclude catalytic material. The mixture of conductive particles and catalytic particles will result in an efficient transfer of electrons from the catalytic conductive layer to the electrolyte. The catalytic particles are distributed among the conductive particles. The conductive particles may form a matrix enclosing the catalyst particles and holding them in place.

In one aspect, the catalyst particles are substantially evenly distributed among the conductive particles. By distributing the catalytic particles substantially uniformly in the catalytic conductive layer, the transfer of electrons from the conductive particles to the electrolyte is improved.

In one aspect, the conductive particles are bonded to each other, such as by sintering. The conductive particle may form a matrix containing the catalytic particles. The catalytic particles are embedded in a matrix of conductive particles. For example, the catalytic conductive layer contains sintered conductive particles and catalytic particles located between the conductive particles. The conductive particles act as a glue between the catalyst particles and hold the catalyst particles in positions between the conductive particles.

In one aspect, the size of the conductive particles is larger than the size of the catalytic particles. When the catalyst material is more expensive than the conductive material, it is preferable that the size of the catalyst particles be smaller than the size of the conductive particles in order to reduce costs.

In one aspect, at least 80% of the catalyst particles are less than 50 nm in diameter. Such small particles have a high surface/volume ratio and will provide efficient catalysis with a reduced volume of catalyst material. If the catalytic material is platinum, this will reduce the cost of the catalytic material.

In one aspect, at least 80% of the conductive particles are greater than 100 nm in diameter. Preferably, the size of the conductive particles is from 0.1 to 5 µm.

In one aspect, the catalytic conductive layer contains a mixture of titanium particles and platinized carbon particles. Preferably, the titanium particles are attached to each other, for example by sintering.

In one aspect, the conductive material in the porous catalytic conductive layer is the same material as used in the second conductive layer.

In one aspect, the thickness of the catalytic conductive layer is less than 100 microns, and preferably less than 20 microns. In one aspect, the thickness of the catalytic conductive layer is at least 1 µm, preferably at least 5 µm, and most preferably at least 10 µm.

In one aspect, the thickness of the second conductive layer is at least 1 µm, preferably at least 10 µm, and preferably at least 20 µm.

The thickness of the first conductive layer is preferably also kept thin so as to have a short distance between the light absorbing layer and the catalytic conductive layer and the counter electrode. The thickness of the first conductive layer may be from 0.1 to 40 µm and preferably from 0.3 to 20 µm.

In one aspect, the porous insulating layer comprises a porous substrate made of an insulating material.

In one aspect, the porous catalytic conductive layer comprises a porous substrate made of an insulating material, and the conductive particles of the catalytic conductive layer form a conductive network through the insulating material of the porous substrate. Conductive particles and catalytic particles are located in the pores of the porous substrate. The conductive mesh provides an expansion of the counter electrode which extends into the porous substrate.

By "the conductive particles form a conductive network through the insulating material" is meant that the particles form one or more electrically conductive paths through the insulating material of the porous substrate.

In one aspect, the dye-sensitized solar cell assembly comprises a porous substrate made of an insulating material, the porous insulating layer being the first part of the porous substrate, and the conductive particles of the catalytic conductive layer forming a conductive network through the second part of the porous substrate. Due to the conductive mesh in the porous substrate, the distance between the counter electrode and the light absorbing layer no longer depends on the thickness of the porous substrate. Thus, the thickness of the insulating layer can be reduced, and thereby the distance between the counter electrode and the light absorbing layer can be reduced.

The porous insulating layer prevents a short circuit between the first conductive layer and the catalytic conductive layer. The conductive particles in the catalytic conductive layer form a conductive network through the insulating substrate material. The conductive mesh is in electrical contact with the second conductive layer of the counter electrode and will therefore greatly increase the conductive surface area of the counter electrode.

In one aspect, the electrolyte is any of an iodide/tri-iodide (iodide/triiodide) electrolyte, a copper complex electrolyte, or a cobalt complex electrolyte, or a combination thereof.

In one aspect, the conductive medium contains iodide (I ^- ) and triiodide (I ₃ ^- ), and the content of triiodide in the conductive medium is from 1 mm to 20 mm. This embodiment makes it possible to achieve high power generation at low light intensities.

In one aspect, the porous substrate is a sheet containing woven microfibers extending throughout the solar cell assembly. For example, woven microfibers are made from glass fibers. A sheet containing woven microfibers running throughout the solar cell assembly helps to provide a flexible, twistable and impact resistant photovoltaic charger.

In one aspect, the porous light absorbing layer includes colored TiO ₂ . The porous light absorbing layer including the dyed TiO ₂ is non-brittle and does not depend on the angle of the incident light.

In one aspect, the light absorbing layer is a porous layer of TiO ₂ nanoparticles with an absorbing organic dye. Examples of organic dyes are: N719, N907, B11, C101. Other organic dyes may also be used.

In one aspect, the solar cell stack generates at least 5 μW/cm ² when the intensity of light received by the light absorbing layer is 200 lux, and at least 600 μW/cm ² when the intensity of light received by the light absorbing layer is 20,000 lux. The solar cell unit generates more than 5 μW/cm ² when measured on the active area of the solar cell when the intensity of the light received by the light absorbing layer is 200 lux. It has been proven by tests that the solar cell assembly according to the invention is capable of generating more than 5 μW/cm ² when the light intensity received by the light absorbing layer is 200 lux. Lux is an appropriate unit for measuring light intensity (illuminance) because it measures the intensity of light perceived by human eyes. Lux is often used to measure the intensity of light (illumination) indoors, which is mostly in the part of the electromagnetic spectrum that is visible to the human eye. Accordingly, it is useful to relate the efficiency of a solar cell unit to the light intensity measured in lux.

In one aspect, the solar cell stack generates more than 5.5 μW/cm ² when the light intensity received by the light absorbing layer is 200 lux. It has been proven by tests that the solar cell assembly according to the invention is capable of generating more than 5.5 μW/cm ² when the light intensity received by the light absorbing layer is 200 lux.

In one aspect, the solar cell stack generates at least 150 μW/cm ² when the light intensity received by the light absorbing layer is 5000 lux.

In one aspect, the solar cell stack generates at least 600 μW/cm ² and preferably at least 700 μW/cm ² when the light intensity received by the light absorbing layer is 20,000 lux. More specifically, the solar cell stack is capable of generating at least 5 to 600 μW/cm ² when the light intensity received by the light absorbing layer is from 200 to 20,000 lux. The power generated by the solar cell unit increases substantially linearly as the intensity of light received by the light absorbing layer increases from 200 to 20,000 lux. Thus, the solar cell stack is capable of generating power in a wide range of different lighting conditions. The solar cell unit works in both poor and excellent lighting conditions, such as indoors under artificial light, outdoors in the shade, and when exposed to strong sunlight.

By substantially linear is meant that the power output increases linearly with increasing light intensity over at least the major portion of the 200 and 20,000 lux range. For example, the power produced may be slightly off-line with intensities between 200 and 1000 lux.

In one aspect, the solar cell stack generates a voltage that changes by less than 40% when the intensity of light received by the light absorbing layer changes between 200 and 50,000 lux. For example, the solar cell stack generates a voltage that changes less than 0.4 V, and preferably less than 0.3 V, when the intensity of light received by the light absorbing layer changes between 200 and 50,000 lux. The voltage generated by the solar cell unit is quite uniform in the range of 200-50000 lux. This means that the generated voltage is sufficient regardless of the light intensity. Due to the fact that the voltage output from the solar cell package changes only slightly when the intensity of the light received by the light absorbing layer changes between 200 and 50,000 lux, it is possible to use a boost converter to amplify the voltage for a wide range of different light intensities without undue loss in conversion time.

The level of voltage generated depends on the ions in the electrolyte. For example, if the electrolyte contains copper ions, the solar cell package can generate an open circuit voltage of about 1V when the light intensity received by the light absorbing layer is 20,000 lux, and if the electrolyte contains iodide and triiodide ions, the solar cell package can generate a voltage of 0. 65 V in open circuit when the light intensity received by the light absorbing layer is 20,000 lux.

In one aspect, the solar cell stack generates an open circuit voltage of at least 0.3 volts when the light intensity received by the light absorbing layer is 200 lux.

Further, the solar cell unit generates an open circuit voltage of less than 1.2 V when the light intensity received by the light absorbing layer is 20,000 lux.

In one aspect, the current generated by the solar cell unit increases linearly as the intensity of light received by the light absorbing layer increases from 200 to 20,000 lux.

In one aspect, the solar cell stack generates a current of at least 15 μA/cm ² when the intensity of light received by the light absorbing layer is 200 lux, and the current generated by the solar cell stack increases linearly when the intensity of light received by the light absorbing layer increases from 200 to 20000 lux. Due to the linearity and the fact that the solar cell unit does not produce any current when the light intensity is zero and produces a current of at least 15 µA/cm ² when the light intensity is 200 lux, the solar cell unit produces a current of about 1500 µA/cm ² when the intensity of light received by the light absorbing layer is 20,000 lux. Thus, the solar cell stack is capable of generating sufficient power to charge the batteries of electronic devices over a wide range of light intensities.

The solar cell assembly is preferably a monolithic dye sensitized solar cell assembly. A monolithic block of a dye-sensitized solar cell is characterized in that all layers are deposited directly or indirectly on the same porous substrate.

The first and second conductive layers are located on the shadow side of the light absorbing layer, i. e. the side opposite the side receiving the light. Thus, the first and second conductive layers are located on the same side of the light absorbing layer.

Another object of the present invention is to provide a photovoltaic charger specially adapted for charging an electronic device.

This problem is solved by a photovoltaic charger comprising a dye-sensitized solar cell assembly according to the invention, a sheath encapsulating the solar cell assembly, a first conductor electrically connected to a first conductive layer, and at least one second conductor electrically connected to a second conductive layer. layer, and the photovoltaic charger contains only one single solar cell package and a boost converter electrically connected to the first and second conductors, and the boost converter is adapted to increase the voltage from the solar cell block when the current from the solar cell block decreases.

The photovoltaic charger according to the invention is capable of charging devices when lighting conditions are very poor. For example, a photovoltaic charger is capable of charging electronic devices when the only light source is a lamp. This allows you to charge electronic devices indoors at night.

Moreover, since the photovoltaic charger has only one single solar cell unit, there will be no problem from partial shading. Even if parts of the surface of the solar cell block are shaded, the unshaded parts will still produce current. Thus, the photovoltaic charger according to the invention is still capable of charging an electronic device even when the active area of the photovoltaic charger is partially shaded. By active area is meant the area of a solar cell block that contributes to power generation when it is exposed to light.

The first conductor acts as a current collector and collects currents from the first conductive layer. The second conductor acts as a current distributor and distributes currents across the second conductive layer. The photovoltaic charger has a single, scalable solar cell that can be fitted to any shape or size of a portable electronic device. A plurality of down conductors is not required on the visible side of the photovoltaic charger, and the absence of visible down conductors results in a visually uniform surface. Thus, the photovoltaic charger can be used on the portable electronic device without affecting the structure of the device. In other words, the portable electronic device can be powered by a photovoltaic charger that is invisible to the observer. Another advantage of not having a plurality of connectors located across the surface of the solar cell stack is that a larger area of the solar cell stack can be used for power generation since there are no multiple current collectors to block incoming light.

Additional advantages of the photovoltaic charger include low cost, impact resistance, flexibility, and independence from the angle of incoming light.

Additionally, the size of a single solar cell unit is scalable, and accordingly, the size and power of the photovoltaic charger can be adapted to the size and power consumption of different devices to be charged. By increasing the area of the solar cell block, the power generated by the photovoltaic charger increases.

The photovoltaic charger comprises a boost converter electrically coupled to the first and second conductors, and the boost converter is adapted to increase the voltage from the solar cell pack while lowering the current from the solar cell pack. Thus, the photovoltaic charger is capable of generating a sufficient voltage level to charge electronic devices under a wide range of different lighting conditions. Different types of batteries require different voltage levels. The boost converter allows the rechargeable batteries of electronic devices to be supplied with the voltage level required by the type of battery. The voltage generated by a single solar cell stack is too low to charge some types of batteries, such as lithium batteries, which require about 3.6 volts. In the prior art, the required voltage is achieved by arranging multiple solar cell stacks connected in series. According to the invention, the required voltage is achieved by connecting a boost converter to a single solar cell stack. Thus, it is possible to provide a photovoltaic charger having only one solar cell unit capable of charging batteries that require different voltage levels.

In one aspect, the boost converter is configured to convert the voltage from the solar cell stack to a voltage that is in the range of 1 to 10 V. Thus, the photovoltaic charger is capable of charging batteries used for many types of electronic devices for consumer applications, such as lithium or nickel batteries.

In one aspect, the boost converter is configured to convert a voltage from 0.25 to 1 V to a voltage above 3 V, and preferably above 3.5 V. Thus, a photovoltaic charger can be used to charge a battery having a load voltage above 3 V , such as a lithium battery, which typically requires a load voltage of 3 to 4.5 V depending on how the battery is loaded.

In one aspect, the boost converter is capable of handling currents from 15 to 9000 mA/cm ² . Thus, the boost converter is capable of handling currents from the solar cell stack from 200 lux to 120,000 lux, which is full sunlight.

In one aspect, the shell is made of transparent plastic. This feature contributes to providing a flexible, twistable and impact resistant photovoltaic charger.

In some aspects, the shape and size of a single solar cell stack is adapted to the size and shape of the portable electronic device that it powers. Additionally, the active area of the solar cell unit adapts to the power required to charge the device.

In one aspect, the shortest distance from one side to the other of the active area of the solar cell stack is greater than 1 cm, and preferably greater than 1.5 cm.

In one aspect, the shortest distance from one side to the other of the active area of the solar cell stack is greater than 1.5 and the active area of the solar cell stack is greater than 25 cm ² . Such a photovoltaic charger, for example, is used to charge headphones.

In one aspect, the shortest distance from one side to the other of the active area of the solar cell is greater than 10 cm. Thus, the active area of the solar cell stack is greater than 100 cm ² . Such a photovoltaic charger, for example, is used to charge a tablet.

For example, an electronic device is any of a headphone, tablet, or mobile phone. For example, the electronic device is a headphone having a headband that is pulled over the wearer's head, with a photovoltaic charger located on the upper surface of the headband. For example, the electronic device is a tablet, and the photovoltaic charger is integrated into the tablet or into the tablet case. For example, the portable electronic device is a mobile phone, and the photovoltaic charger is integrated in the mobile phone or in the mobile phone case.

Another object of the present invention is to provide a method for manufacturing a solar cell block.

The method contains:

- preparation of the first dye containing conductive particles,

- preparation of a second dye containing a mixture of conductive particles and catalytic particles,

- providing a porous insulating substrate,

- applying the first layer of the first dye to the first side of the porous insulating substrate,

- applying a second layer of the second dye to the second side of the porous insulating substrate,

- sintering the porous insulating substrate with the applied layers to convert the first layer into a porous first conductive layer and the second layer into a porous catalytic conductive layer, and

- heating the porous insulating substrate with sintered conductive layers in air to form titanium oxide on the surfaces of the first conductive layer.

The method further comprises arranging the porous light-absorbing layer on top of the porous first conductive layer, infiltrating the ionic electrolyte into the porous layers (electrolyte impregnation of the porous layers), and sealing the solar cell stack.

At least some of the method steps may be performed in a different order, for example, the second layer may be applied before the first layer. Heating in air may, for example, be carried out simultaneously with the formation of a light absorbing layer over the porous first conductive layer.

Brief description of the drawings

Fig. 1 shows a first example of a dye-sensitized solar cell stack.

Fig. 2 shows a second example of a dye-sensitized solar cell stack.

Fig. 3 shows a top view of a photovoltaic charger in accordance with one or more embodiments of the invention.

Fig. 4 shows a cross section of the photovoltaic charger shown in FIG. 3, enlarged.

Fig. 5 shows a plot of measured values for generated voltage (mV) for light intensities (illuminances) from 200 to 20,000 lux for a third example of a solar cell package having an electrolyte containing iodide and triiodide ions.

Fig. 6 shows a diagram based on measured values for generated current (μA/cm ² ) for light intensities from 200 to 20,000 lux for a third example of a solar cell package.

Fig. 7 shows a graph based on measured values for generated power per area (µW/cm ² ) for light intensities from 200 to 20,000 lux for a third example of a solar cell package having an electrolyte containing iodide and triiodide ions.

Fig. 8 shows a plot of measured values for generated voltage (mV) for light intensities from 200 to 50,000 lux for a third example of a solar cell package having an electrolyte containing copper ions.

Fig. 9 shows a graph based on measured values for generated current (μA/cm ² ) for light intensities from 200 to 50,000 lux for a third example of a solar cell package having an electrolyte containing copper ions.

Fig. 10 shows a graph based on measured values for generated power per area (µW/cm ² ) for light intensities from 200 to 50,000 lux for a third example of a solar cell package having an electrolyte containing copper ions.

Detailed description of the preferred embodiments of the invention

Aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. The dye sensitized solar cell assembly and photovoltaic charger disclosed herein may, however, be implemented in a variety of different forms and should not be construed as being limited to the aspects set forth herein. Like reference numerals in the drawings refer to like elements.

The terminology used here is only intended to describe specific aspects of the disclosure and is not intended to limit the invention.

Unless otherwise defined, all terms used herein have the same meaning as generally understood by a person skilled in the art to which this disclosure belongs.

Fig. 1 shows an example of a block 1 of a dye-sensitized solar cell. The solar cell block 1 includes a working electrode comprising a light absorbing layer 10 and a porous first conductive layer 12 for extracting photogenerated electrons from the light absorbing layer 10. Preferably, the light absorbing layer 10 is porous. The light absorbing layer 10 is disposed over the first conductive layer 12. The solar cell assembly 1 further comprises a porous insulating layer 105 made of an insulating material, with the first conductive layer 12 overlying the porous insulating layer 105. For example, the porous insulating layer 105 is a porous substrate.

The solar cell block 1 has a counter electrode comprising a porous catalytic conductive layer 106 comprising a porous conductive material 107' and catalytic particles 107'' dispersed in the porous conductive material 107' to improve electron transfer to an electrolyte 110 located in the pores of the porous catalytic conductive layer 106. In one aspect, the conductive material 107' of the porous catalytic conductive layer 106 comprises conductive particles 107'. For example, the porous catalytic conductive layer 106 contains a mixture of conductive particles 107' and catalytic particles 107'', as shown in the enlarged figure on the right in FIG. 1. Preferably, the catalyst particles 107'' are substantially uniformly distributed in the conductive material 107' of the catalytic conductive layer 106.

The porous catalytic conductive layer 106 is located adjacent to the porous insulating layer 105 on the opposite side of the insulating layer compared to the first conductive layer.

In one aspect, the counter electrode of the solar cell assembly 1 comprises a second conductive layer 16 including a conductive material. The porous catalytic conductive layer 106 is located between the porous insulating layer 105 and the second conductive layer 16. The catalytic conductive layer 106 is in electrical contact with the second conductive layer 16. The second conductive layer 16 is essentially non-catalytic. The first conductive layer 12, the catalytic conductive layer 106, and the insulating layer 105 are porous, allowing electrolyte to permeate through the layers to reach the light absorbing layer 10. In one aspect, the second conductive layer is also porous. In an alternative embodiment, the second conductive layer 16 may be omitted.

The solar cell block 1 also contains an ionic electrolyte 110 for transferring charges between the counter electrode and the working electrode. For example, an ionic electrolyte is a liquid or a gel. The ionic electrolyte is located in the pores of the porous layers, such as the porous first conductive layer 12, the catalytic conductive layer 106, the porous insulating layer 105, and the light absorbing layer 10. The ionic electrolyte may also be located in the pores of the second conductive layer 16 if the second conductive layer is porous.

The conductive material in the porous catalytic conductive layer 106 is part of the counter electrode. Therefore, since the catalytic conductive layer 106 and the second conductive layer 16 are in electrical contact, the effective distance between the light absorbing layer 10 and the second conductive layer 16 is shorter, and the resistance loss in the conductive medium is therefore reduced. Additionally, the catalytic particles 107'' facilitate the transfer of electrons from the conductive material 107' in the porous catalytic conductive layer to the electrolyte 110.

In one aspect, the catalytic conductive layer 106 comprises a mixture of conductive particles 107' and catalytic particles 107''. The conductive particles are in electrical contact with the second conductive layer 16. Preferably, the conductive particles are non-catalytic and exclude catalytic material. The mixture of conductive particles and catalytic particles will result in an efficient transfer of electrons from the catalytic conductive layer to the electrolyte.

The conductive particles of the catalytic conductive layer include a conductive material and are in electrical contact with the second conductive layer 16. The catalytic particles are dispersed among the conductive particles. The conductive particles act as a holder for the catalytic particles and hold them in place. The conductive particles may form a matrix to accommodate and hold the catalyst particles in place. For example, the matrix contains sintered metal particles.

In one aspect, the catalyst particles are substantially evenly distributed among the conductive particles. By distributing the catalytic particles substantially uniformly in the catalytic conductive layer, the transfer of electrons from the conductive particles to the electrolyte is improved. In one aspect, the conductive particles are bonded to each other, such as by sintering. The conductive particle may form a matrix containing the catalytic particles. The catalytic particles are embedded in a matrix of conductive particles. For example, the catalytic conductive layer contains sintered conductive particles, and the catalytic particles are located between the conductive particles. The conductive particles act as a glue between the catalyst particles and hold the catalyst particles in position between the conductive particles.

In one aspect, at least 80% of the 107″ catalyst particles are less than 50 nm in diameter. Such small particles have a high surface/volume ratio and will provide efficient catalysis with a reduced volume of catalytic material. If the catalytic material is platinum, this will reduce the cost of the catalytic material. In one aspect, at least 80% of the conductive particles are greater than 100 nm in diameter. Preferably, the size of the conductive particles is from 0.1 to 15 µm.

The conductive material of the first and second conductive layers 12, 16 may, for example, be a metal, a metal alloy, a metal oxide or other conductive materials such as titanium, titanium alloys, nickel or nickel alloys. It is possible that the first and second conductive layers 12, 16 contain titanium or an alloy thereof. For example, the conductive material of the first and second conductive layers is titanium. For example, the first conductive layer 12 may contain sintered titanium particles to be porous. Titanium is preferred because it is highly corrosion resistant and ionic electrolytes are often highly corrosive.

The conductive material 107' in the catalytic conductive layer 106 may, for example, be made of metal, metal alloy, metal oxide, or other conductive materials such as titanium, titanium alloys, nickel or nickel alloys, indium, or indium oxide. Catalyst particles 107'' are made, for example, of carbon-based materials such as graphene or graphite, or carbon black, or carbon nanotubes, platinum, or combinations thereof.

In one aspect, the 107″ catalyst particles comprise carbon particles. Carbon is inexpensive and environmentally friendly. More preferably, the 107″ catalyst particles include platinized carbon particles. Platinum is a better catalyst than carbon, but is expensive. By using a combination of platinum and carbon, a good catalyst is provided at a lower cost. Catalytic particles can be electrically conductive as well as catalytic. For example, carbon is electrically conductive as well as catalytic. However, carbon is a poor conductor compared to other conductive materials such as titanium.

The electrical conductivity of the first and second conductive layers 12, 16 may be higher than the electrical conductivity of the catalytic conductive layer 106. The combination of the catalytic conductive layer 106 with a mixture of conductive material and catalytic particles and the second conductive layer 16 substantially free of catalytic particles will result in an efficient transfer of electrons from the conductive particles 107' of the counter electrode into the electrolyte; and the high electrical conductivity of the counter electrode.

Preferably, the catalytic conductive layer contains from 1 to 50 wt.% catalytic particles. The wt % of catalyst particles required to achieve efficient electron transfer from the conductive material to the electrolyte depends on the size and shape of the catalyst particles and the type of material in the catalyst particles and the type of conductive material. For example, the catalytic conductive layer may contain from 5 to 30 wt.% catalytic particles. This range is suitable, for example, when the conductive particles consist of titanium and the catalytic particles consist of platinized carbon. However, as mentioned earlier, the wt.% of the catalytic particles depends on the size of the particles.

For example, if the conductive material 107' in the catalytic conductive layer 106 is titanium, the catalyst particles 107'' contain platinized carbon, and the size of the catalytic particles 107'' is smaller than the size of the conductive particles 107', the catalytic conductive layer 106 may contain from 5 to 30 wt. % catalytic particles 107'' to ensure efficient transfer of electrons to the electrolyte. For example, the catalytic conductive layer contains from 50 to 90 wt.% titanium, at least 5 wt.% carbon and at least 0.001 wt.% platinum. Titanium has good mechanical strength and holds the platinized carbon particles in their positions in the catalytic conductive layer. Thus, carbon, platinum and titanium together provide a catalytic conductive layer with high mechanical strength and high electron transfer capacity in the electrolyte.

In one aspect, the thickness t1 of the catalytic conductive layer 106 is at least 1 µm, preferably at least 5 µm, and most preferably at least 10 µm. In one aspect, the thickness t1 of the catalytic conductive layer 106 is less than 100 microns, and preferably less than 20 microns. In one aspect, the thickness t2 of the porous insulating layer 105 is 0.1 µm to 20 µm, and preferably 0.5 µm to 10 µm. In one aspect, the thickness t4 of the second conductive layer 16 is at least 1 µm, preferably at least 10 µm, and preferably at least 20 µm.

The first conductive layer 12 includes an insulating oxide layer 109 formed on the surface of the conductive material, as shown in the enlarged left figure in FIG. 1. This oxide layer 109 is formed by, for example, oxidizing the conductive material of the first conductive layer. The conductive material suitably comprises a metal or metal alloy, such as titanium. The surface of the conductive material oxidizes when exposed to air. The oxide layer 109 may be formed by performing heat treatment on the first conductive layer in an oxidizing environment so that the conductive material becomes oxidized. The insulating oxide layer 109 provides an electrically insulating layer on the conductive material that at least partially prevents the transfer of electrons between the first conductive layer 12 and the electrolyte located in the pores of the first conductive layer 12.

In one aspect, the first conductive layer 12 comprises porous titanium and a titanium oxide layer 109 formed on the surfaces of the porous titanium such that the oxide layer 109 electrically insulates the porous titanium of the first conductive layer and thereby prevents the porous titanium in the first conductive layer from leaking electrons into the electrolyte. in the pores of the first conductive layer. Thus, the efficiency of the solar cell unit is improved. For example, the first conductive layer 12 contains titanium sintered particles 107, and the surfaces of the titanium sintered particles 107 are coated with a titanium oxide layer 109, as shown in the enlarged left figure in FIG. 1. In one aspect, the thickness of the titanium oxide layer is greater than 5 nm, preferably greater than 10 nm, and more preferably greater than 20 nm. In one aspect, the thickness of the titanium oxide layer is from 10 to 200 nm, and preferably from 20 to 50 nm.

Specifically, the combination of an insulating oxide layer 109 that prevents electrons from leaking from the first conductive layer into the liquid-based electrolyte, and a counter electrode comprising a catalytic conductive layer 106 including catalytic particles 107'' dispersed in the porous conductive material 107, and a non-catalytic the conductive layer 16, which improves the efficiency of the counter electrode, will result in an efficient solar cell assembly that is capable of generating power in a wide range of different lighting conditions. The solar cell unit operates in both poor and excellent lighting conditions, such as indoors under artificial light and outdoors in shade and strong sunlight.

In one aspect, the electrolyte is any of an iodide/triiodide electrolyte, a copper complex electrolyte, or a cobalt complex electrolyte, or a combination thereof. In one aspect, the electrolyte contains iodide (I ^- ) and triiodide (I ₃ ^- ) and the content of triiodide in the conductive medium is from 1 mm to 20 mm. This embodiment makes it possible to achieve high power generation at low light intensities.

The insulating material of the porous insulating layer 105 is, for example, an inorganic material (substance) that is interposed between the first conductive layer 12 and the catalytic conductive layer 106 and insulates the first conductive layer 12 and the catalytic conductive layer 106 from each other. The porous insulating layer 105 is, for example, made of glass fibers, ceramic microfibers, or laminated crystal materials such as 2D materials or nanosheets.

Block 1 solar cell may contain a porous substrate. The porous insulating layer 105 may comprise the entire substrate, as shown in FIG. 1, or only a portion 114a of the porous substrate 114 as shown in FIG. 2. In one aspect, the porous substrate is a sheet containing woven microfibers extending throughout the solar cell assembly. For example, woven microfibers are made from glass fibers.

Fig. 2 shows an example of a dye-sensitized solar cell 1' comprising a porous substrate 114 made of an insulating material. The same or corresponding parts in FIG. 1 and 2 are designated by the same reference numerals. The difference between the solar cells 1' and 1 is that the porous catalytic conductive layer 106' contains the first part 114a of the porous substrate 114, and the porous insulating layer 105 contains the second part 114b of the porous substrate 114. The catalytic conductive layer 106' contains the conductive particles 107' and catalytic particles 107'' located in the pores of the first part 114a of the porous substrate 114. The conductive particles 107' of the catalytic conductive layer 106' form a conductive mesh 209 through the insulating material of the part 114a of the porous substrate 114. The conductive mesh 209 forms one or more electrically conductive paths through an insulating material of the first porous substrate portion 114a. The conductive particles 107' and the catalytic particles 107'' are located in the pores of the porous substrate 114. Preferably, these particles are smaller than the pores in the porous substrate so that they can penetrate into the substrate during manufacture of the solar cell. The conductive mesh 209 provides an expansion of the second conductive layer that extends into the porous substrate 114. Due to the conductive mesh in the porous substrate, the distance between the counter electrode and the light absorbing layer is no longer dependent on the thickness of the porous substrate. Thus, the thickness of the insulating layer can be reduced, and thereby the distance between the counter electrode and the light absorbing layer can be reduced. Accordingly, the resistance losses in the electrolyte are reduced.

In the following, an example of a manufacturing method of the solar cell unit 1 will be briefly described.

1) Preparation of a first dye containing conductive particles made of an electrically conductive material. The conductive particles are made, for example, of titanium hydride.

2) Preparation of a second dye containing a mixture of conductive particles and catalytic particles. The conductive particles are made of, for example, titanium hydride (TiH ₂ ) and the catalytic particles are, for example, platinized carbon particles.

3) Providing a porous insulating substrate, such as fiberglass.

4) Applying conductive particles to one side of the porous insulating substrate, for example by printing a first dye including titanium hydride particles on one side of the porous insulating substrate.

5) Subsequent provision of air-drying of the printed first dye.

6) Applying a mixture of catalytic particles and conductive particles to the other side of the porous insulating substrate, for example by printing a second dye, including titanium hydride particles and platinized carbon particles, to the other side of the porous insulating substrate.

7) Subsequently allowing air-drying of the printed second dye.

8) Applying the conductive particles over the catalytic conductive layer, for example by printing a first dye comprising titanium hydride particles onto the layer of the mixture of catalytic particles and conductive particles.

9) Subsequent provision of air-drying of the printed first dye.

10) The porous insulating substrate with printed layers is then sintered in vacuum, for example at 600°C for an hour. During the sintering process, titanium hydride is converted to titanium. Therefore, a first conductive layer including sintered titanium, a second conductive layer including sintered titanium, and a catalytic conductive layer including sintered titanium and platinized carbon particles located in pores between the sintered titanium are formed during the sintering process.

11) A porous insulating substrate with sintered conductive layers is heated in air to form titanium oxide on the surfaces of the sintered titanium of the first conductive layer.

12) A TiO ₂ based dye is printed over the first conductive layer and then dried. Glass cloth with said layers is heated, for example, up to 600°C. The deposited TiO ₂ layer is then sintered.

13) The TiO ₂ sintered layer is sensitized with a dye to form a light absorbing layer.

14) An ionic electrolyte, such as an iodide/triiodide (I ^- /I ₃ ^- ) redox electrolyte, seeps into the porous layers.

15) The solar battery is sealed, for example, using a transparent shell.

Alternatively, step 11 may be performed simultaneously with the sintering of the TiO ₂ layer in step 12.

The porous conductive layers can be applied to the porous substrate by any of screen printing, die-cutting, spraying, or wet copy transfer.

During the heat treatment in step 11, titanium oxide is also formed on the catalytic conductive layer. It can be assumed that the oxide layer on the catalytic conductive layer will prevent the transfer of electrons between the conductive material and the electrolyte located in the pores of the catalytic conductive layer. Surprisingly, it has been found that catalytic particles, for example platinized carbon particles, allow the transfer of electrons from the conductive material to the electrolyte despite the oxide layer on the conductive material of the catalytic conductive layer.

Fig. 3 shows a plan view of an example of a photovoltaic charger 200. The photovoltaic charger 200 is specially adapted to power portable electronic devices that can be used indoors as well as outdoors, such as headphones, laptops, tablets, mobile phones, and remote controls. The photovoltaic charger 200 may also be used to power miniature electronic devices embedded in other physical devices such as vehicles and consumer electronic devices referred to as the Internet of Things (IoT).

The photovoltaic charger 200 includes a solar cell stack 1, a shell 5 containing the solar cell stack 1, a first conductor 18, and a second conductor 20. The photovoltaic charger may further comprise connectors (not shown) for connecting the photovoltaic charger 200 to an electronic device. . The solar cell block 200 is a monolithic type DSC. Monolithic type DSC differs from standard DSC in that it is built on a single substrate, with multiple layers arranged on the substrate.

The shell contains a plurality of passages in connection with the first and second conductors for connecting the photovoltaic device with an external device. In other words, there are passages in the shell to access the power generated by the photovoltaic device. Some kind of wired connection will go through the passages. For example, the first and second conductors may exit the sheath through passageways to connect to wiring to power an external device. Alternatively, wires from outside the sheath pass through the passages and are electrically connected to the first and second conductors. The passages are tightly fitted to the wires passing through the jacket so that no gas or liquid can enter through the passages. For example, the passages are holes in the sheath, tightly fitted to the wires passing through the sheath.

The sheath 5 comprises a plurality of passages 7a-b arranged in connection with the first conductor 18 and the second conductor 20 for connecting the photovoltaic device 1 to an external device and thereby accessing the power generated by the photovoltaic device. For example, passages lead through openings in the shell. Some type of wiring will go through the holes. For example, the first and second conductors 18, 20 may exit the sheath through passages 7a-b to connect to wiring to power an external device, as shown in FIG. 3. Alternatively, wires from outside the sheath pass through the passages and are electrically connected to the first and second conductors. The passages are tightly fitted to (fitted to) the wires so that no gas or liquid can pass through them. The passages may be made having wires or conductors which must pass through the provided openings when the sheath is located on the solar cell block 1. The shell consists of a top sheet 5a and a bottom sheet 5b, which are, for example, adhesive films that are placed together on top of the solar cell unit 1. Alternatively, the top and bottom sheets are made of flexible plastic, and the edges of the top and bottom sheets are bonded to each other by melting the plastic. If wires/conductors are already provided between the sheets prior to bonding and protrude at the edges of the sheets, passages will be created during bonding. Alternatively, the passages comprise through-holes in the shell made after encapsulation of the solar cell package. The through holes are sealed after the wires/conductors are placed in the through holes. The locations of the passages will depend on the position of the first and second conductors. The number of passes may vary. There is at least one passage for each of the first and second conductors. However, it is also possible to have multiple passages for each of the first and second conductors.

Fig. 4 shows an enlarged section of a portion of the photovoltaic charger 200 shown in FIG. 3. The photovoltaic charger 200 includes one solar cell unit 1 or solar cell unit 1', which is described in more detail with reference to FIG. 1 and 2. For example, the light absorbing layer 10 contains colored TiO ₂ . Conventional dyes known in the art may be used. The dye is chosen to provide good solar cell efficiency, especially in combination with a copper-based conductive medium. The light absorbing layer 10 is located on top of the first conductive layer 12. The porous light absorbing layer 10 is a porous TiO ₂ layer deposited on the first conductive layer 12. The TiO ₂ layer contains TiO ₂ particles colored by absorption of dye molecules on the surface of the TiO ₂ particles. The light absorbing layer 10 is located on the upper side of the solar cell unit 1. The top side should be facing the light to allow light to hit the dye molecules of the working electrode.

The first conductive layer 12 is in direct electrical contact with the light absorbing layer 10. In this example, the second conductive layer 16 is porous. However, in an alternative embodiment, the second conductive layer 16 need not be porous. For example, the second conductive layer may be made of a metal foil. In this example, the porous insulating layer 105 contains at least a portion of the porous substrate. The porous substrate provides electrical isolation between the first conductive layer 12 and the catalytic conductive layer 106. The first conductive layer 12 and the catalytic conductive layer 106 are separated by a physically and electrically porous substrate. The porosity of the porous substrate will allow ion transport through the insulating layer 105. The porosity of the first conductive layer 12 and the catalytic conductive layer 106 will allow ion transport between the counter electrode and the working electrode.

The photovoltaic charger 200 contains only one single solar cell unit 1. At least the first conductive layer 12 and the porous substrate continuously extend through the entire solar cell stack. The light absorbing layer 10 and the second conductive layer 16 extend continuously through at least the main portion of the solar cell package.

The solar cell block 1 is filled with an electrolyte for charge transfer between the counter electrode and the light absorbing layer 10. The electrolyte is, for example, a traditional I ^- /I ₃ ^- electrolyte or a similar electrolyte, or a copper (Cu)-based electrolyte, or an electrolyte based on cobalt complex compounds (Co). The electrolyte contains ions, for example iodide ions (I ^- ) and triiodide ions (I ₃ ^- ) or copper ions (Cu ²⁺ and Cu ⁺ ). Sunlight is collected by the dye, generating photo-excited electrons that are injected into the conductive band of TiO ₂ particles and further collected by the first conductive layer. At the same time, ions in the electrolyte transport electrons from the second conductive layer to the light absorbing layer 10. The first conductor 18 collects electrons from the first conductive layer and the second conductor provides electrons to the second conductive layer so that the solar cell stack can continuously generate power from the incoming photons. .

The electrolyte penetrates into the pores of the light absorbing layer 10, the first conductive layer 12, the porous insulating layer 105, the second conductive layer 16 and the catalytic conductive layer 106, allowing ions to be transferred between the light absorbing layer 10 and the second conductive layer 16 and thereby transfer electrons from the working electrode to the light absorbing layer.

There are a variety of dyes that can be used, and in some aspects, the dye contains a triarylamine organic dye containing any or a mixture of dyes in the donor-π bridge-acceptor (D-π-A) class and in the donor-acceptor-π class. acceptor bridge (D-A-π-A). Such dyes give good solar cell efficiency, especially in combination with a copper-based conductive medium. Photosensitizers of the first class include, for example, substituted (diphenylaminophenyl)-thiophene-2-cyanoacrylic acids or substituted (diphenylaminophenyl)cyclopenta-dithiophene-2-cyanoacrylic acids. The second class includes, for example, substituted (((diphenylaminophenyl)benzothia-diazolyl)-cyclopentadithiophenyl)aryl/heteroaryl-2-cyanoacrylic acids or (((diphenylaminophenyl)-cyclopentadithiophenyl)benzothiadiazolyl)aryl/heteroaryl-2-cyanoacrylic acids.

The first conductor 18 is electrically connected to the first conductive layer 12, and the second conductor 20 is electrically connected to the second conductive layer 16. For example, the first and second conductors are made of metal to achieve high electrical conductivity.

The shell 5 comprises a top sheet 5a covering the top side of the solar cell block 1 and a bottom sheet 5b covering the bottom side of the solar cell block. The shell 5 encloses the solar cell package and the electrolyte, and acts as a hydraulic barrier to the electrolyte and prevents leakage of the electrolyte from the photovoltaic charger 200. The top sheet 5a is transparent, or at least the portion covering the active area of the solar cell package 1 is transparent. The top sheet 5a on the top side of the solar cell package covers the light absorbing layer 10 and allows light to pass through. The top and bottom sheets 5a-b are made of a resin material, for example. The polymer material is strong and impact resistant and flexible. The top and bottom sheets 5a-b are sealed at the edges to protect the solar cell package from the surrounding atmosphere and prevent the electrolyte from evaporating or leaking from the inside of the solar cell package.

In one example, the porous substrate is a sheet containing a woven microfiber fiber. A microfiber is a fiber having a diameter of less than 10 μm and greater than 1 nm. The web of woven microfibers can be made very thin and mechanically very strong. The web of woven microfibers contains holes between the woven threads. The porous substrate may further comprise one or more layers of nonwoven microfibers disposed on the woven microfibers to at least partially block the openings between the filaments. Additionally, the non-woven layer provides a flat surface on the substrate suitable for applying an even conductive layer to the substrate by printing. The substrate is made, for example, of glass, silicon oxide (SiO ₂ ), alumina (Al ₂ O ₃ ), aluminosilicate or quartz. Accordingly, the non-woven and woven microfibers of the porous substrate are made of glass fibers, which provides a strong and flexible substrate. The thickness of the web of woven microfibers is respectively 4 µm to 30 µm, preferably 4 µm to 20 µm, in order to provide the required mechanical strength, while at the same time it is thin enough to allow rapid transport of ions between the counter electrode and the working electrode.

In one aspect, the light absorbing layer 10 and the first conductive layer 12 are opaque. In this example, the top surface of the solar cell block 1 is uniformly black, as shown in FIG. 3. TiO ₂ light absorbing layer is black. There are no conductors running over the surface of the solar cell unit 1, as is the case in prior art solar cell panels. This is because the photovoltaic charger 200 contains only a single solar cell stack, rather than a plurality of solar cell stacks connected in series as in the solar panels used in prior art photovoltaic chargers.

Solar cell block size, i.e. the length and width of the solar cell unit may vary depending on which device it is intended to charge. Accordingly, the active area of the solar cell unit may vary depending on the required power of the device to be charged. There are no restrictions on the possible shape and size of the solar cell block. For example, the size of the solar cell block may vary from 1×1 cm with an active area of 1 cm ² to 1×1 m with an active area of 1 m ² . There is no upper limit to the length and width of the solar cell stack. However, a solar cell unit larger than 1×1 m may become cumbersome to process when manufacturing the solar cell unit.

The photovoltaic charger 200 includes a single solar cell stack 1 and a boost converter 22 electrically coupled to first and second conductors 18, 20. A boost converter, also referred to as a boost regulator, is a DC to DC power converter that boosts voltage at decrease in current from its input to its output. The voltage produced by a single solar cell bank is too low to charge certain types of batteries, such as lithium batteries, which require at least 3.6V. element. The required voltage level is achieved by connecting the boost converter to a single solar cell unit. Thus, it is possible to provide a photovoltaic charger having only one single solar cell unit capable of charging batteries that require different voltage levels.

The photovoltaic charger 200 includes connectors 3, 4 for connecting the photovoltaic charger to the battery of the electronic device that it charges. Boost converter 22 includes input terminals electrically connected to the first and second conductors 18, 20 and output terminals electrically connected to connecting elements 3, 4.

The level of voltage generated depends on the ions in the electrolyte. For example, if the electrolyte contains copper ions, the solar cell stack generates an open circuit voltage of about 1 V when the light intensity received by the light absorbing layer is 20,000 lux, and if the electrolyte contains iodide and triiodide ions, the solar cell stack generates a voltage of about 0 .65 V in open circuit when the light intensity received by the light absorbing layer is 20,000 lux. However, the solar cell unit 1 generates a voltage changing by a maximum of 0.4 V in an open circuit when the intensity of light received by the light absorbing layer changes between 200 and 20,000 lux. The voltage conversion requirement of the boost converter depends on the required voltage of the rechargeable battery. Most types of rechargeable batteries used for electronic devices for consumer applications require a voltage of 1 to 10 V. The boost converter generates a stable voltage at the level required by the rechargeable battery. Preferably, boost converter 22 is capable of converting the output voltage and current from the solar cell stack to a voltage level that is between 1 and 10 V. Different boost converters can be used depending on the desired output voltage. Thus, the photovoltaic charger is capable of charging batteries used for many types of electronic devices, such as lithium batteries (3.6V), NiCd and NiMH batteries (1.25V).

Tests have shown that the solar cell stack is capable of generating a current of at least 15 μA/cm ² when the intensity of light received by the light absorbing layer is 200 lux, and a current of at least 1500 μA/cm ² when the intensity of light received by the light absorbing layer is is 20,000 lux. Thus, the solar cell stack is capable of generating enough power to charge the batteries of electronic devices over a wide range of light intensities.

In accordance with some aspects, at least the first conductive layer 12 and the porous substrate 114 continuously extend through the entire block 1 of the solar cell. The light absorbing layer 10 and the second conductive layer 16 extend continuously through at least the main portion of the solar cell package.

Measurements of the generated power per area for different lighting conditions were made on the example of a photovoltaic charger according to the invention, including a single solar cell unit 1. In this example, the solar cell block 1 has a size of 14.5×23.4 cm and an active area of 340 cm ² . The electrolyte of the solar cell unit 1 contains iodide and triiodide ions, and the first and second conductive layers are made of titanium (Ti). An unloaded PV charger is exposed to light from 200 to 20,000 lux (lumens per square meter) and the output voltage and output current from the PV charger are measured. The measurement results are shown in Table 1 below. The total generated power is determined based on the measured current and voltage, and the generated power per area is determined by dividing the total power by the active area of the solar cell stack.

Table 1. Measurements of generated power per active area, current per active area, voltage and duty cycles (ff) for light intensities from 200 to 20000 lux for solar cell bank 1 having an electrolyte containing iodide ions (I ^- ) and triiodide - ions (I ₃ ^- ). The content of triiodide is from 1 mm to 20 mm. Iodide works as an oxidizing agent and triiodide works as a reducing agent.

Suite μW / cm ² Isc (µA/cm ² ) Voc (mV) ff (%) 200 6.2 18 483 72 500 18 44 521 77 1000 37 90 542 76 2000 80 179 565 79 3000 123 266 576 80 5000 208 445 591 79 6000 249 531 600 78 10000 405 880 614 75 20000 730 1700 650 69

Performance measurements of solar cell stack 1 at different light intensities (illuminances) (intensities are measured in lux) can be performed by irradiating the solar cell stack with light and simultaneously scanning the applied electrical voltage across the solar cell stack to measure and obtain the solar cell I-V characteristic. Measurements were taken using a warm white LED as the light source.

The resulting IV curve under illumination provides information on open circuit voltage, short circuit current, duty cycle, power, and power conversion efficiency. By obtaining IV curves at different light intensities, it is possible to collect information on the dependence of light intensity on open circuit voltage, short circuit current, duty cycle (the ratio of the maximum power received to the product of open circuit voltage and short circuit current), power and conversion efficiency (COP) power, respectively.

The result from table 1 is obtained from measurements on a sample solar cell block 1. Measurements on different solar cell units of this type may vary. For example, the generated power per area may be from 5 μW/cm ² to 8 μW/cm ² .

The light source used for irradiating the light of the solar cell may vary depending on the application of the solar cell. For indoor applications, it may be useful to use electric fluorescent lamps or indoor LED lighting. For solar cell applications that use ambient lighting, it may be useful to irradiate the solar cell with light using a solar simulator to generate artificial sunlight.

The light intensity of a light source can be measured in various ways, for example, using a luxmeter or a spectroradiometer placed at the same position as the solar cell stack relative to the light source. In this case, the light intensity was measured using a luxmeter.

Table 1 shows the specific power in microwatts per square centimeter (µW/cm ² ) for various light intensities measured in lux. As can be seen from the table, the solar cell unit 1 generates 6.2 µW/cm ² when the light intensity received by the solar cell unit 1 is 200 lux, generates 208 µW/cm ² when the light intensity received by the solar cell unit 1 is 5000 lux, and generates 730 μW/cm ² when the light intensity received by the solar cell unit 1 is 20,000 lux. This shows that the photovoltaic charger is capable of generating more than 5 μW/cm ² and even more than 5.5 μW/cm ² when the light intensity received by the light absorbing layer is 200 lux. It also shows that the photovoltaic charger is capable of generating more than 700 μW/cm ² when the light intensity received by the light absorbing layer is 20,000 lux. Thus, the solar cell unit 1 is at least capable of generating 5.5 to 700 μW/cm ² when the light intensity received by the light absorbing layer is 200 to 20,000 lux. The power generated by the photovoltaic charger increases substantially linearly when the intensity of light received by the light absorbing layer increases from 200 to 20,000 lux. Thus, the photovoltaic charger is capable of generating power in a wide range of different lighting conditions.

Fig. 5 shows a diagram of the generated voltage (mV) for light intensities from 200 to 20,000 lux based on the measured values in Table 1. As can be seen from the diagram and Table 1, the solar cell unit 1 is capable of generating an open circuit voltage of 480 mV when the intensity of light received block 1 solar cell, is 200 lux. Further, the photovoltaic charger 200 is capable of generating an open circuit voltage of 650 mV when the intensity of the light received by the solar cell unit 1 is 20,000 lux. As can be seen from the diagram, the increase in the generated voltage is greatest between 200 and 3000 lux. The generated voltage is essentially linear between 3000 and 20000 lux. As can be seen from Table 1, the difference in generated voltage between 200 and 20,000 lux is only 167 mV. Thus, the solar cell unit 1 generates a voltage changing by less than 0.2 V in an open circuit when the intensity of light received by the light absorbing layer changes from 200 to 20,000 lux. Accordingly, the difference in generated voltage between 200 and 20,000 lux is approximately 35%.

Fig. 6 shows a diagram of the generated current (μA/cm ² ) for light intensities from 200 to 20,000 lux based on the measured values in Table 1. As can be seen from the figure, the current increases linearly.

Fig. 7 shows a graph of the generated power per area (µW/cm ² ) for light intensities from 200 to 20,000 lux, calculated from the measured voltage and current values in Table 1. As can be seen from the graph, the measured power is essentially proportional to the intensity of the incoming light in the range of 200 -20000 lux.

Additional measurements of the generated power per area for different lighting conditions were made on another example of a photovoltaic charger according to the invention. In this example, the electrolyte of the solar cell unit 1 contains copper ions (Cu ⁺ and Cu ²⁺ ), which is the only difference between the photovoltaic chargers being measured. The measurement conditions were the same. The unloaded photovoltaic charger 200 is exposed to light from 200 to 20,000 lux (lumens per square meter), and the output voltage and output current from the photovoltaic charger are measured. The measurement result is shown in Table 2 below.

Table 2. Measurements of generated power per active area, current per active area, voltage and duty cycle (ff) for light intensities from 200 to 20000 lux for solar cell bank 1 having an electrolyte containing copper ions; Cu ⁺ as a reducing agent and Cu ²⁺ as an oxidizing agent.

Suite μW / cm ² Isc (µA/cm ² ) Voc (mV) ff (%) 0 0 0 0 0 200 12.8 25 699 72.7 500 38 67 762 74.3 1000 85.4 140 800 76.1 2000 186 290 835 77.1 5000 498 737 881 76.6 10000 1020 1490 915 75.1 20000 2020 2960 943 72.3 30000 2920 4390 954 69.7 40000 3720 5750 958 67.6 50000 4410 7000 958 65.8

As can be seen from Table 2, the solar cell unit 1 generates 12.8 µW/cm ² when the light intensity received by the solar cell unit 1 is 200 lux, generates 498 µW/cm ² when the light intensity received by the solar cell unit 1 is is 5000 lux, and generates 2020 μW/cm ² when the intensity of light received by the solar cell unit 1 is 20000 lux. This shows that this photovoltaic charger 200 is capable of generating more than 12 μW/cm ² when the light intensity received by the light absorbing layer 10 is 200 lux. It also shows that the photovoltaic charger 200 is capable of generating more than 2,000 μW/cm ² when the light intensity received by the light absorbing layer 10 is 20,000 lux. The power generated by the photovoltaic charger increases substantially linearly when the intensity of light received by the light absorbing layer increases from 200 to 20,000 lux. Thus, the photovoltaic charger 200 is capable of generating power in a wide range of different lighting conditions.

Fig. 8 shows a diagram of the generated voltage (mV) for light intensities from 200 to 50,000 lux based on the measured values in Table 2. As can be seen from the diagram and Table 2, the solar cell unit 1 is capable of generating an open circuit voltage of 699 mV when the intensity of the light received block 1 solar cell, is 200 lux. Further, the photovoltaic charger 200 is capable of generating an open circuit voltage of 943 mV when the intensity of the light received by the solar cell unit 1 is 20,000 lux. As can be seen from the diagram, the generated voltage is essentially linear between 3000 and 50000 lux. As can be seen from Table 2, the difference in generated voltage between 200 and 20,000 lux is only 244 mV. Accordingly, the difference in generated voltage between 200 and 20,000 lux is approximately 35%. The difference in generated voltage between 200 and 50,000 lux is only 259 mV. Thus, the solar cell unit 1 generates a voltage varying by less than 300 mV in an open circuit when the intensity of light received by the light absorbing layer changes between 200 and 50,000 lux. Accordingly, the difference in generated voltage between 200 and 50,000 lux is approximately 37%.

Fig. 9 shows a diagram of the generated current (µA/cm ² ) for light intensities from 200 to 50,000 lux based on the measured values in Table 2. As can be seen from the figure, the current rises linearly.

Fig. 10 shows a graph of the generated power per area (µW/ ^cm2 ) for light intensities from 200 to 50,000 lux, calculated from the measured voltage and current values in Table 1. As can be seen from the graph, the measured power is essentially proportional to the intensity of the incoming light in the range of 200 -20000 lux.

The present invention is not limited to the disclosed embodiments, but may be changed and modified within the scope of the following claims. For example, the second conductive layer 16 may be omitted. Eliminating the second conductive layer can reduce the range of different lighting conditions under which the solar cell stack can generate enough power to power the device. However, in some applications, lighting conditions do not change as much and a solar cell unit capable of producing power in a smaller range is sufficient.

Claims (33)

1. Block (1; 1’) of a dye-sensitized solar cell, containing: - a working electrode containing a porous light-absorbing layer (10), - a porous first conductive layer (12), including a conductive material for extracting photogenerated electrons from the light-absorbing layer (10), the light-absorbing layer being located on top of the first conductive layer, a porous insulating layer (105) made of an insulating material, wherein the first conductive layer (12) is formed on one side of the porous insulating layer (105), - a counter electrode containing a porous catalytic conductive layer (106; 106') formed on the opposite side of the porous insulating layer (105), and - ionic electrolyte for electron transfer from the counter electrode to the working electrode, located in the pores of the porous first conductive layer (12), the porous catalytic conductive layer (106; 106') and the porous insulating layer (105), wherein the first conductive layer (12) contains an insulating an oxide layer (109) formed on the surfaces of the conductive material, and the porous catalytic conductive layer (106; 106') contains the conductive material (107') and catalytic particles (107'') dispersed in the conductive material (107') to improve transfer of electrons from a conductive material to an electrolyte, while the thickness of the insulating oxide layer (109) is from 10 to 200 nm. 2. The dye-sensitized solar cell assembly according to claim 1, wherein the catalytic particles (107'') are uniformly distributed in the conductive material (107') of the porous catalytic conductive layer (106; 106'). 3. The dye sensitized solar cell assembly according to any one of the preceding claims, wherein the conductive material (107') of the porous catalytic conductive layer (106) forms a porous matrix and the catalytic particles (107'') are dispersed in the porous matrix. 4. The dye-sensitized solar cell assembly according to any one of the preceding claims, wherein said catalytic conductive layer (106; 106') contains from 1 to 50% by weight of catalytic particles (107''). 5. The dye-sensitized solar cell assembly according to any one of the preceding claims, wherein the counter electrode comprises a second conductive layer (16) including a conductive material in electrical contact with a porous catalytic conductive layer (106; 106'), wherein the second conductive layer (16 ) is non-catalytic, and the porous catalytic conductive layer (106; 106') is located between the porous insulating layer (105) and the second conductive layer (16). 6. The dye-sensitized solar cell assembly according to any one of the preceding claims, wherein said conductive material (107') of the first conductive layer (12) is titanium and said insulating oxide layer (109) is titanium oxide formed on titanium surfaces. 7. The dye-sensitized solar cell assembly of any one of the preceding claims, wherein said catalyst particles (107'') are platinized carbon particles. 8. The dye-sensitized solar cell assembly according to any one of the preceding claims, wherein said conductive material (107') of the porous catalytic conductive layer (106; 106') is titanium. 9. The dye sensitized solar cell assembly according to any one of the preceding claims, wherein said conductive material (107') of the porous catalytic conductive layer (106; 106') is titanium, said catalytic particles (107'') are platinized carbon particles, and the porous the catalytic conductive layer contains from 50 to 90 wt.% titanium, at least 5 wt.% carbon and at least 0.001 wt.% platinum. 10. The dye sensitized solar cell assembly of any one of the preceding claims, wherein at least 80% of said catalyst particles (107'') are less than 50 nm in diameter. 11. The dye sensitized solar cell assembly according to any one of the preceding claims, wherein said insulating oxide layer (109) is between 20 and 50 nm thick. 12. The dye-sensitized solar cell unit according to any one of the preceding claims, wherein the solar cell unit (1; 1') produces at least 5 μW/cm ² when the light intensity received by the light absorbing layer (10) is 200 lux, and at least 600 μW/cm ² when the intensity of light received by the light absorbing layer (10) is 20,000 lux. 13. A dye-sensitized solar cell assembly according to any one of the preceding claims, wherein the solar cell assembly (1; 1') generates a voltage varying by less than 40% when the intensity of light received by the light absorbing layer (10) varies between 200 and 50,000 lux . 14. The dye-sensitized solar cell assembly according to any one of the preceding claims, wherein the solar cell assembly (1; 1') generates a current of at least 15 µA/cm ² when the light intensity received by the light absorbing layer (10) is 200 lux, and the current generated by the solar cell unit increases linearly when the intensity of the light received by the light absorbing layer (10) increases from 200 to 20,000 lux. 15. Photoelectric charger (200) adapted for charging an electronic device, containing: - a block (1, 1') of a dye-sensitized solar cell according to claim 1, - a shell (5) encapsulating the solar cell unit, - a first conductor (18) electrically connected to the first conductive layer (12), and - at least one second conductor (20) electrically connected to the second conductive layer (16), moreover, the photovoltaic charger (200) contains only one single solar cell block (1, 1') and a boost converter (22), electrically connected to the first and second conductors (18, 20), wherein the boost converter is adapted to increase the voltage from the solar cell pack while at the same time decreasing the current from the solar cell pack. 16. A method for manufacturing a solar cell block according to claim 1, the method comprising: - preparation of the first dye containing conductive particles, - preparation of a second dye containing a mixture of conductive particles (107') and catalytic particles (107''), - providing a porous insulating substrate (105), - applying the first layer of the first dye to the first side of the porous insulating substrate, - applying a second layer of the second dye to the second side of the porous insulating substrate, - sintering the porous insulating substrate with the applied layers, converting the first layer into a porous first conductive layer (12) and the second layer into a porous catalytic conductive layer (106; 106'), and - heating the porous insulating substrate with sintered conductive layers in air to form titanium oxide on the surfaces of the first conductive layer.

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