Tandem solar cell and fabricating method thereof

A tandem solar cell and fabricating method thereof are disclosed. The steps of the fabricating method comprises: a top inverted solar cell having a plurality of inverted solar sub-cells is provided; a bottom normal solar cell having a plurality of normal solar sub-cells accompanying with the inverted solar sub-cells is provided; and processing fit process of the top inverted solar cell and the bottom normal solar cell is executed, wherein an interlayer is disposed between the bottom normal solar cell and the top inverted solar cell, and the interlayer includes a plurality of conductive dots. The plurality of inverted solar sub-cells and normal solar sub-cells are placed with an offset distance from each other, and a plurality of solar sub-cells are formed after the pressing fit process, and the plurality of solar sub-cells are series/parallel connection each other by electrically connecting the plurality of conductive dots.

FIELD OF THE INVENTION

The present invention relates to a tandem solar cell device and fabricating method thereof, and more particularly to an organic tandem solar cell device with a structure of series/parallel connection and fabricating method thereof.

BACKGROUND OF THE INVENTION

Because of several problems of fossil fuel energy with high cost and greenhouse effect, solving energy issue becomes an important task. The power generation of solar cells are applied by infinite solar energy and do not need fossil fuel, thus, solar cells now are utilized in satellite, space technology, and mobile communication. In view of energy saving, demands of the effective resource use and environmental pollution preventing, solar cells increasingly become attractive energy generators.

In 1954, the first inorganic solar cell formed on silicon (Si) is produced by Bell Laboratory in America, and such solar cell can transfer the solar radiation to electrical energy by photoelectric effect. However, the cost of the common solar cell formed on silicon wafer is higher than that of the others traditional power generation method (ex. fossil fuel thermal power plant), and doesn't meet the requirement of the production cost. Especially, the cost of solar cell formed on mono-crystalline silicon is high-priced. The cost of solar cells formed on polycrystalline silicon is lower than that of the solar cells formed on mono-crystalline silicon and the fabricating processes of the solar cells formed on polycrystalline silicon are easier than that of the solar cells formed on mono-crystalline silicon. However, the polycrystalline silicon solar cell is still difficult to popularize in daily life.

In recent years, organic materials such as polymer utilized to fabricate solar cell are catching academia and industry's attention. Polymer solar cells are fabricated by polymer materials similar with plastic property, and have advantages such as light weight, good flexibility, ruggedness, impact resistance, and low cost. Moreover, polymer solar cells also can be fabricated on a flexible plastic substrate or a thin metal foil substrate, and fabricated by spin-coating or doctor-blading with low cost. In view of these advantages, polymer solar cells are being as noteworthy new generation of solar cells.

Otherwise, the structures of organic polymer solar cells comprise a single-layer structure, a heterojunction structure, and a bulk heterojunction structure which is popular materials in research. The evolution of these structures is for the purpose of obtaining a solar cell device with higher energy conversion power and lowest cost to fabricate. However, promotion of the energy conversion power of single solar cell structure still has restriction. Therefore, a solar cell device which is utilized to stack several solar sub-cells in series/parallel connection is provide for increasing the energy conversion power of a solar cell.

A traditional fabricating method of a solar cell device with stacking several solar sub-cells in series/parallel connection is utilized to stack these solar sub-cells layer by layer. Regarding toFIG. 1, it shows a structure of a solar cell device with stacking several solar sub-cells in series connection. A solar cell device100is consisted of a first solar sub-cell10and a second solar sub-cell20. The solar cell device100comprises a glass substrate101with a transparent conductive oxide layer, and a first solar sub-cell10is formed on the glass substrate101. Then, a silver (Ag) layer107is formed on the first solar sub-cell10, and the silver layer is utilized to provide an electron-hole pair recombination. The second solar sub-cell20is further formed on the silver layer107. The first solar sub-cell10and the second solar sub-cell20have the same structure, which is consisted of a first heterogeneous material layer103,109and a second heterogeneous material layer105,111respectively, to form a heterogeneous interface. Finally, an exciton barrier layer113and a silver electrode115are formed on the second solar sub-cell20.

The traditional fabricating method of the mentioned-above solar cell device100is described as below. At first, a glass substrate101with a transparent conductive oxide layer is provided. Then, a first heterogeneous material layer103, a second heterogeneous material layer105, a silver layer107, another first heterogeneous109, another second heterogeneous material layer111, an exciton barrier layer113, and silver electrode115are formed sequentially on the glass substrate101. However, this fabricating method of the solar cell device100is needed to process in a vacuum environment, and difficult to reduce cost of production.

Furthermore, an organic polymer solar cell can be fabricated by using a simple process to achieve the effect of a large area. However, a multi-layer device fabricated by a solution process will produce solution miscible problem. The solution miscible problem will occur in a coating procedure of a second polymer layer after forming a first polymer layer. The coating procedure of the second polymer layer causes the first polymer layer dissolving such that the interface between of the first polymer layer and the second polymer layer blurred, and the total thickness of the structure also will be less by expectancy, and thereby greatly affecting the quality of the multilayer device.

Moreover, in recent years, the volume of electric device is reduced, and the volume of the accessory battery is also needed to reduce. However, in order to increase the energy conversion power of the mentioned-above solar cell structure formed by stacking in series/parallel connection, the numbers of the stacked solar sub-cells are increased due to the thickness of the solar cell device unable reducing effectively.

Otherwise, the mentioned-above method of stacking several solar sub-cells in series/parallel connection is to stack each solar sub-cell on the substrate sequentially. Therefore, the more solar sub-cells are stacked, the larger thickness of the solar cell device will be produced. Furthermore, the more stacked solar sub-cells also will produce more problems of layer by layer structure, such as the layout of electrodes are also needed to add for electrically connection of each solar sub-cell; or the energy conversion power of the solar cell device doesn't reach the expectancy.

Therefore, there is a need to develop an effective fabricating method of stacking several solar sub-cells in series/parallel connection, and the tandem solar cell device can add its energy conversion power effectively and the quality of the solar cell device can be ensured. Moreover, the fabricating method not only reduces the production cost but also reduces the thickness of the solar cell structure.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a tandem solar cell with high energy conversion power and small volume.

The second object of the present invention is to provide a fabricating method of a tandem solar cell with high energy conversion power and small volume.

The third object of the present invention is to provide a fabricating method of a tandem solar cell for series/parallel connection of several solar sub-cells without in a vacuum environment for reducing cost of the tandem solar cell.

The fourth object of the present invention is to solve the solution miscible problem of each layer of the structure of the tandem solar cell device fabricated by the traditional fabricating method of the tandem solar cell for series/parallel connection of several solar sub-cells.

In view of the foregoing objects, the present invention provides a fabricating method of a tandem solar cell, the steps comprising: providing a top inverted solar cell having a plurality of inverted solar sub-cells; providing a bottom normal solar cell having a plurality of normal solar sub-cells corresponding with the inverted solar sub-cells; and executing a pressing fit process of the top inverted solar cell and the bottom normal solar cell; wherein an interlayer and an anti-reflux protective device for preventing reflux occurrence are set between the bottom normal solar cell and the top inverted solar cell in the pressing fit process, wherein the interlayer includes a plurality of conductive dots, and the plurality of inverted solar sub-cells and normal solar sub-cells are placed with an offset distance from each other, a solar sub-cell is formed after pressing fit process of the inverted solar sub-cell and the normal solar sub-cell, and plurality of the solar sub-cell for series/parallel connection by the plurality of conductive dots.

Moreover, the present invention provides a tandem solar cell, comprising: a top inverted solar cell having a plurality of inverted solar sub-cells; a interlayer having a plurality of conductive dots and the interlayer connected to the top inverted solar cell; a bottom normal solar cell having a plurality of normal solar sub-cells, and the bottom normal solar cell connected to the interlayer; wherein a solar sub-cell is constructed by the inverted solar sub-cell and normal solar sub-cell, and the conductive dot is utilized to connect the inverted solar sub-cell and adjacent the normal solar sub-cell to construct a series/parallel connection the plurality of solar sub-cells structure.

One advantage of the present invention is that the tandem solar cell with series/parallel connection of several solar sub-cells is fabricated without in a vacuum environment, and the fabricating method is easy to practice for reducing cost of produce. The solution miscible problem occurred by the traditional fabricating method of a tandem solar cell is also resolved.

Another advantage of the present invention is that the tandem solar cell with series parallel connection of several solar sub-cells of the present invention has a small volume and high energy conversion power.

A detailed description is given in the following embodiments and with references to the accompanying drawings and claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention hereinafter will be described in greater detail with preferred embodiments of the invention and accompanying illustrations. Nevertheless, it should be recognized that the preferred embodiments of the invention are not provided to limit the invention but to illustrate it. The present invention can be practiced not only in the preferred embodiments herein mentioned, but also in a wide range of other embodiments besides those explicitly described. Further, the scope of the present invention is expressly not limited to any particular embodiments except what is specified in the appended Claims.

The present invention and embodiments now are described in detail. In diagrams and descriptions as below, the same symbols are utilized to represent the same or similar elements. The main of features of the embodiments of the present invention are described in highly simplified illustration. Otherwise, the drawings of the present invention do not depict every characteristic of the actuality embodiments, and all elements of the drawings are not depicted in proportional size but in relative size.

The present invention discloses a tandem solar cell with structure of series/parallel connection and the fabricating method thereof. An embodiment of the fabricating method of the tandem solar cell with structure of series/parallel connection according to the present invention is introduced first. Regarding toFIGS. 2-3, they are utilized to describe the fabricating method of the tandem solar cell with the structure of series/parallel connection, and accompany withFIG. 4, which shows the flow-chart thereof, for illustrating.

At first, regarding to the step411of the flow-chart of the fabricating method shown inFIG. 4, it shows that a top inverted solar cell with a plurality of inverted solar sub-cells is provided. Regarding toFIG. 2, it shows a diagram of the fabricating method of the tandem solar cell according to the present invention. A top inverted solar cell200is provided, and the top inverted solar cell200comprises a substrate201. A plurality of inverted solar sub-cells203are formed on the substrate201. In one embodiment of the present invention, the top inverted solar sub-cell200has three inverted solar sub-cells203, which comprise a first inverted solar sub-cell2031, a second inverted solar sub-cell2032, and a third inverted solar sub-cell2033. It's only used to describe the detail of the embodiment of the present invention, and do not limit the scopes of the present invention. For one person skilled in the art, increasing or decreasing the number of the inverted solar sub-cells203is the same technology with the present invention and needs to encompass in the scope of the present invention. In certain embodiments of the present invention, the substrate201may be any substrate for solar cell, for example, a glass substrate or a flexible substrate. In another certain embodiments of the present invention, the substrate201comprises a glass substrate or a flexible substrate with a transparent conductive oxide film, and the transparent conductive oxide film is utilized to being the cathode of the top inverted solar cell. In this embodiment, the substrate201comprises a glass substrate with an indium tin oxide (ITO) film, and the ITO film is the cathode of the top inverted solar cell.

Then, regarding to the step413of the flow-chart of the fabricating method shown inFIG. 4, it shows that a bottom normal solar cell with a plurality of normal solar sub-cell corresponding to the plurality of inverted solar sub-cell is provided. Regarding toFIG. 2, a bottom normal solar cell300is provided, and the bottom normal solar cell300comprises a substrate301. A plurality of normal solar sub-cells303are formed on the substrate301. In this embodiment, the numbers of the normal solar sub-cells303are also three corresponding to the numbers of the inverted solar sub-cells203. The normal solar sub-cells303comprise a first normal solar sub-cell3031, a second normal solar sub-cell3032, and a third normal solar sub-cell3033. For one person skilled in the art, increasing or decreasing the numbers of the normal solar sub-cells303is the same technology with the present invention and needs to encompass in the scope of the present invention. In certain embodiments of the present invention, the substrate301may be any substrate for solar cell, for example, a glass substrate or a flexible substrate. In another certain embodiments of the present invention, the substrate301comprises a glass substrate or a flexible substrate with a transparent conductive oxide film, and the transparent conductive oxide film is utilized to being the anode of the bottom normal solar cell. In this embodiment, the substrate301comprises a glass substrate with an ITO film, and the ITO film is the anode of the bottom normal solar cell.

Finally, regarding to the step415of the flow-chart of the fabricating method shown inFIG. 4, it shows a pressing fit process of the top inverted solar cell and the bottom normal solar cell is executed, and the plurality of the inverted solar sub-cells and the normal solar sub-cells are placed with an offset distance from each other (misalignment). Regarding toFIG. 2, it shows the tandem solar cell before the pressing fit process of the top inverted solar cell200and the bottom normal solar cell300, and an interlayer400is disposed between the top inverted solar cell200and the bottom normal solar cell300. The interlayer400further includes a plurality of conductive dots410,420. In this embodiment, the top inverted solar cell200comprises three inverted solar sub-cells203which are a first inverted solar sub-cell2031, a second inverted solar sub-cell2032, and a third inverted solar sub-cell2033, respectively. The bottom normal solar cell300comprises three normal solar sub-cells303corresponding to the three inverted sub-cells203, and the three normal solar sub-cells303are a first normal solar sub-cell3031, a second normal solar sub-cell3032, and a third normal solar sub-cell3033. The interlayer is also divided to a first interlayer401, a second interlayer402, and a third interlayer403corresponding to the three inverted solar sub-cells203and the three normal solar sub-cells303. Moreover, a first conductive dot410is disposed between the first interlayer401and the second interlayer402, and a second conductive dot420is disposed between the second interlayer402and the third interlayer403.

Furthermore, an anti-reflux protective device is also fabricated during the pressing fit process for preventing dispensable refluxes occurrence. The dispensable refluxes mean a phenomenon caused by short circuits of few sub-cells, and will reduce the efficiency of the device dramatically. In this embodiment, the anti-reflux protective device comprises an anti-reflux diode.

In the pressing fit process, the plurality of the inverted solar sub-cells and the normal solar sub-cells are placed with an offset distance from each other. In other words, the inverted solar sub-cells203aren't aligned to the normal solar sub-cells303but staggered arrangement for pressing fit. Regarding to the embodiment shown inFIG. 2, in the pressing fit process, the first inverted solar sub-cell2031and the first normal solar sub-cell3031are placed with an offset distance from each other, and the first interlayer401is placed in the overlap part (area). The second inverted solar sub-cell2032and the second normal solar sub-cell3032are also placed with an offset distance from each other, and so on. Moreover, the offset distance causes an overlapping area between the first normal solar sub-cell3031and the second inverted solar sub-cell2032, and the first conductive dot410is placed on the overlapping area for electrical connecting the first normal solar sub-cell3031and the second inverted solar sub-cell2032, and so on. In certain embodiments of the present invention, the pressing fit process is utilized a roller to press, such as roll-to-roll process.

Regarding toFIG. 3, it shows a tandem solar cell device of the present invention after pressing fit process for fabricating. A first solar sub-cell is consisted of the first inverted solar sub-cell2031, the first interlayer401, and the first normal solar sub-cell3031; a second solar sub-cell is consisted of the second inverted solar sub-cell2032, the second interlayer402, and the second normal solar sub-cell3032; and a third solar sub-cell is consisted of the third inverted solar sub-cell2033, the third interlayer403, and the third normal solar sub-cell3033. Moreover, the first conductive dot410is placed in the overlapping area between the first normal solar sub-cell3031and the second inverted solar sub-cell2032for electrical connecting the first normal solar sub-cell3031and the second inverted solar sub-cell2032; similarly, the conductive dot420is placed in the overlapping area between the second normal solar sub-cell3032and the third inverted solar sub-cell2033for electrical connecting the second normal solar sub-cell3032and the third inverted solar sub-cell2033. Therefore, the first solar sub-cell and the second solar sub-cell are connected electrically by the first conductive dot410, and the second solar sub-cell and the third solar sub-cell are connected electrically by the second conductive dot420for series/parallel connection of the first solar sub-cell, the second solar sub-cell, and the third solar sub-cell.

In this embodiment, the top inverted solar cell200and the bottom normal solar cell300are fabricated separately. Regarding toFIG. 5, it shows a structure diagram of the top inverted solar cell. In here, it's only utilized a signal inverted solar sub-cell to describe the top inverted solar cell, but do not limit in this. The top inverted solar cell comprises a substrate201, and an inverted solar sub-cell203is formed on the substrate201. The inverted solar sub-cell203further comprises a hole blocking layer (HBL)213or called electron selective layer, an active layer215or called absorption layer, an electron blocking layer (EBL)217or called a hole selective layer, and a top electrode219.

The substrate201may be any substrate materials for solar cells. In certain embodiments of the present invention, the substrate201comprises a glass substrate or a flexible substrate. In another certain embodiment of the present invention, the substrate201comprises a glass substrate or a flexible substrate with a transparent conductive oxide film, and the transparent conductive oxide film is the cathode of the top inverted solar cell. In this embodiment, the substrate201comprises a glass substrate with an ITO film, and the ITO film is the cathode of the top inverted solar cell. The hole blocking layer213is utilized to block electronic holes. In certain embodiments, the materials of the hole blocking layer213comprise oxide materials such as zinc oxide (ZnO) or cesium carbonate (Cs2CO3), but do not limit in these. In this embodiment, the material of the hole blocking layer213comprises cesium carbonate layer.

The active layer215is utilized to absorb light, and is an interface of donor/acceptor. After illuminating a solar cell device, an exciton will be generated by the absorbed photon and then diffused to the interface of donor/acceptor. Due to the difference of energy band of the heterojunction, the exciton in the interface of donor/acceptor will be divided to electron and electronic hole. The electrons are transmitted to cathode, and the electronic holes are transmitted to anode. In certain embodiments of the present invention, the materials of donor of the active layer215comprise derivatives of thiophene, such as poly(3-hexylthiophene-2,5-diyl) (P3HT), polyacetylene, polyisothianaphthene (PITN), polythiophene, polypyrrol (PPr), polyfluorene (PF), poly(p-phenylene) (PPP) or poly(pheneylene vinylene) (PPV) and the derivatives thereof. In certain embodiments of the present invention, the materials of acceptor of the active layer215comprise related derivatives of fullerene. In another certain embodiments of the present invention, the material of acceptor of the active layer215comprises Buckminsterfullerene (C60) or the derivatives thereof. The Buckminsterfullerene is a kind of small molecule of fullerene, and has several advantages for utilizing to be acceptor, such as high electron affinity, transparent, and good electric conductivity. In this embodiment, the acceptor comprises a 1-(3-methoxycarbonyl) propyl-1-phenyl [6,6] C61 (PCBM), which is a derivative of C60.

The electron blocking layer217is utilized to be a transport layer of electronic holes. In certain embodiments, the electron blocking layer217comprises vanadium pentoxide (V2O5), molybdenum sesquioxide (MoO3), poly (3,4-ethylenedioxythiopene) (PEDOT) or PEDOT:IPA, but does not limit in these. In this embodiment, the electron blocking layer217comprises PEDOT:IPA.

The top electrode219is the anode of the top inverted solar cell. In certain embodiments of the present invention, the top electrode219comprises metal materials with high work function or other transparent conductive oxide. In this embodiment, the top electrode219comprises a sliver layer.

Regarding toFIG. 6, it shows a structure diagram of the bottom normal solar cell. In here, it's only utilized a signal normal solar sub-cell to describe the bottom normal solar cell, but do not limit in this. The bottom normal solar cell300comprises a substrate301, and a normal solar sub-cell303is formed on the substrate301. The normal solar sub-cell303comprises a hole transport layer313, an active layer315, and a top electrode317.

The substrate301is the same with the substrate201, which may be any substrate materials for solar cell. In certain embodiments of the present invention, the substrate301comprises a glass substrate of a flexible substrate. In another certain embodiments of the present invention, the substrate301comprises a glass substrate or a flexible substrate with a transparent conductive oxide film, and the transparent conductive oxide film is the anode of the bottom normal solar cell. In this embodiment, the substrate301comprises a glass substrate with an ITO film, and the ITO film the anode of the bottom normal solar cell. In here, the ITO film has several advantages for being the anode, such as good electric conductivity, good stability of chemical and thermal, and good penetrability in the range of visible light.

The hole transport layer313is utilized to transmit the electronic holes to the anode. In certain embodiments, the materials of the hole transport layer313comprise V2O5, MoO3, PEDOT or PEDOT:IPA, but do not limit in this. In this embodiment, the material of the hole transport layer313comprises PEDOT.

The active layer315is the same with the active layer215, which is an interface of donor/acceptor. In certain embodiment of the present invention, the materials of the donor of the active layer315comprise derivatives of thiophene, such as P3HT, polyacetylene, PITN, polythiophene, PPr, PF, PPP or PPV and the derivatives thereof. In certain embodiments of the present invention, the materials of the acceptor of the active layer315comprise related derivatives of fullerene. In this embodiment, the material of donor comprises P3HT, and the material of acceptor comprises PCBM.

The top electrode317is the cathode of the normal solar cell. In certain embodiments, the materials of top electrode317comprise metal with low work function or other transparent conductive oxide. The anode with high work function and the cathode with low work function can increase an internal electric field within the solar cell for transmitting carriers. In this embodiment, the top electrode317comprises a copper layer.

In certain embodiments of the present invention, the materials of the interlayer400comprise metal or semiconductor materials with bipolar transport property for connecting the top inverted solar cell200and the bottom normal solar cell300. In another embodiment of the present invention, the materials of the interlayer400comprise sliver (Ag) or gold (Au). In this embodiment, the material of the interlayer400is sliver. Furthermore, in this embodiment, the material of the conductive dots410,420comprises sliver for achieving to series/parallel connection of the several solar sub-cell according to the present invention.

The advantages and efficiencies of the tandem solar cell device according to the present invention are described below. In principle, the electric properties of a solar cell device are measured and then drawn a current-voltage characteristic curve thereof for testing the solar cell device. Regarding toFIG. 7andFIG. 8, a current-voltage characteristic curve of dark current of a tandem solar cell device of an embodiment according to the present invention is shown inFIG. 7, and a current-voltage characteristic curve of current generated by illuminating two side of the tandem solar cell device of the embodiment is shown inFIG. 8. In this embodiment, the tandem solar cell device is fabricated by pressing fit a normal solar cell device formed by a single normal solar sub-cell and an inverted solar cell device formed by a single inverted solar sub-cell for testing.

The current-voltage characteristic curve of a solar cell device is described first. In a current-voltage characteristic curve of a solar cell device, it can be read that the current approaches to a constant according to reverse bias. In forward bias, the solar cell device can be turned on and generate photocurrent with increasing voltage to a voltage value. Moreover, some important parameters of testing solar cell device comprise open-circuit voltage (Voc) and short-circuit current (Isc). The open-circuit voltage is defined as a voltage value measured when the external load is infinity; and the short-circuit current is defined as a voltage value measured when the external load is null. Both of the mentioned above parameters can be obtained from the current-voltage characteristic curve of the solar cell device.

Regarding toFIG. 7, it shows a current-voltage characteristic curve of a tandem solar cell device of an embodiment according to the present invention. The dark current is defined as the value of current through the solar cell device without illuminating. In forward bias, current density of the dark current initially measured maintains null. When the voltage value of the forward bias reaches about 1.15˜1.2 volts, the device will be turned on and generate photocurrent shown as the circled area inFIG. 7.

Regarding toFIG. 8, it shows a current-voltage characteristic curve of the mentioned-above tandem solar cell device measured after illuminating. The curve1is a current-voltage characteristic curve measured after illuminating the side of the top inverted solar cell of the tandem solar cell device, and the curve2is a current-voltage characteristic curve measured after illuminating the side of the bottom normal solar cell of the tandem solar cell device. As shown inFIG. 8, the curves are similar with the curve of the dark current. When the voltage value of the forward bias reaches about 1.15˜1.2 volts, the device will be turned on and generate photocurrent shown as the circled area inFIG. 8. In the solar cell, electron-hole pairs will be generated after illuminating, and separated by the internal electric field drifting to cathode and anode respectively. In this moment, the measured photocurrent is the short-circuit current (Isc) and the value of forward bias equates to the open-circuit voltage (Voc). Moreover, the curve1and curve2are almost overlapped inFIG. 8. That means that the solar cell device has good electric conductivity whether illuminating which side of the tandem solar cell device.

The measured value of the open-circuit voltage of the existing tandem solar cell device is between about 0.4˜0.8 volts. The value of the open-circuit voltage of the tandem solar cell device of the present invention is higher than the existing tandem solar cell device as shown inFIGS. 7 and 8. After calculating, it can be obtained a high energy conversion power of the tandem solar cell device according to the present invention.

Therefore, a tandem solar cell device according to the present invention does not need to add the layers of the structure to achieve the objects of series/parallel connection of several solar sub-cells for increasing the open-circuit current and the energy conversion power of the tandem solar cell without adding its thickness. Moreover, the fabricating method of the tandem solar cell device of the present invention is easy to practice. The fabricating method only comprises that a top inverted solar cell and a bottom normal solar cell are fabricated first, and a pressing fit process of the top inverted solar cell and the bottom normal solar cell is executed. Thus, the fabricating method doesn't need to spin coating several layers of different solutions or perform in a vacuum environment. The simply fabricating method can reduce the cost of production effectively for achieving the effects of mass production.

While the embodiments of the present invention disclosed herein are presently considered to be preferred embodiments, various changes and modifications can be made without departing from the spirit and scope of the present invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.