CN101533866A - Solar cell with amorphous silicon multi-structure layer film - Google Patents

Abstract

A solar cell with amorphous silicon multi-structure layer thin film comprises a substrate, a first penetrating electric film, a first photoelectric conversion layer with a-SiN, a second photoelectric conversion layer with a-Si, a third photoelectric conversion layer with a-SiSn, a second penetrating electric film and an upper electrode; the tunable energy bandwidth of the first photoelectric conversion layer is between 1.7ev and 2.3 ev; the tunable energy bandwidth of the second photoelectric conversion layer is about 1.7ev, and the tunable energy bandwidth of the third photoelectric conversion layer is between 0.08ev and 1.1 ev; therefore, the invention has the advantages and effects of large absorption range, high conversion efficiency, lower manufacturing cost and the like.

Description

Solar cells with amorphous silicon multi-layer thin films

technical field

The invention relates to a solar cell, in particular to a solar cell with an amorphous silicon structure layer, which has the advantages of large absorption range, high conversion efficiency and low manufacturing cost.

Background technique

The existing single-level P-I-N solar cell is composed of a-Si (amorphous silicon, that is, amorphous silicon), but the energy gap (bandgap, energy gap, or translated as energy gap) of a-Si is about 1.7ev , for red light and infrared light with less energy, the energy increase after irradiation is less than 1.7eV, so neither can produce photovoltaic special effect to generate electricity. In addition, as shown in Figure 1, the second curve L2 is the absorption spectrum curve of a-Si, and its absorption coefficient is optimal when the wavelength is between 0.45 μm and 0.6 μm (the absorption coefficient is approximately between 0.7 and 1.0) , it can be clearly seen that if it is red visible light with a wavelength between 0.68 μm and 0.76 μm or infrared light with a wavelength above 0.8 μm, the corresponding absorption coefficient is extremely low. In other words, most red light and None of the infrared light is absorbed by a-Si. The fourth curve L4 is the spectral distribution curve of sunlight, and it can be seen that the portion with a wavelength greater than 0.76 μm occupies a considerable proportion, and if it cannot be converted into electrical energy, it will be a great loss. Therefore, the conversion efficiency of existing single-level P-I-N solar cells is limited.

In order to improve the conversion efficiency, it is possible to start with a multi-band or multi-level structure, and the existing multi-band structure solar cells are mostly stacked by GaInP, GaAs and Ge, although the energy gap range has been increased to 0.7 ~1.8ev, but the absorption range is still limited.

Contents of the invention

The main technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art, and provide a solar cell with an amorphous silicon multi-layer thin film, which has the advantage of a large absorption range and achieves the purpose of high conversion efficiency. And has the market competitiveness with lower manufacturing cost.

The technical solution adopted by the present invention to solve its technical problems is:

A solar cell with an amorphous silicon multi-layer thin film is characterized in that it includes: a substrate, which can transmit light; a first transparent electrical film, which is arranged on the substrate and can transmit light; a first photoelectric film The conversion layer is formed by stacking a first P layer, a first I layer and a first N layer, wherein the first I layer is made of a-SiN, and the first photoelectric conversion layer is located on On the first transparent electric film, the adjustable energy bandwidth is between 1.7ev and 2.3ev; a second photoelectric conversion layer is composed of a second P layer, a second I layer and a first Two N layers are stacked, wherein the second I layer is made of a-Si, and the second photoelectric conversion layer is set on the first photoelectric conversion layer, and the adjustable energy bandwidth is 1.7ev Left and right; a third photoelectric conversion layer is formed by stacking a third P layer, a third I layer and a third N layer, wherein the third I layer is made of a-SiSn, and the third The photoelectric conversion layer is arranged on the second photoelectric conversion layer, and the adjustable energy bandwidth is between 0.08ev and 1.1ev, and the energy gap of the first photoelectric conversion layer is larger than that of the second photoelectric conversion layer energy gap, and the energy gap of the second photoelectric conversion layer is larger than the energy gap of the third photoelectric conversion layer; a second transparent film is arranged above the third photoelectric conversion layer and can transmit light; An upper electrode is arranged on the second TT film.

The aforementioned solar cell with amorphous silicon multi-layer thin films, wherein the first, second and third photoelectric conversion layers can be respectively provided with a first buffer layer, a second buffer layer and a third buffer layer, and, The energy gap of the first photoelectric conversion layer is larger than the energy gap of the second photoelectric conversion layer, and the energy gap of the second photoelectric conversion layer is larger than the energy gap of the third photoelectric conversion layer.

The aforementioned solar cell with an amorphous silicon multi-layer thin film, wherein the first photoelectric conversion layer is modulated by the ratio of process gas SiH4/NH3; the second photoelectric conversion layer is modulated by the ratio of process gas SiH4/H2 energy bandwidth; the third photoelectric conversion layer modulates the energy bandwidth by sputtering or vapor deposition.

The beneficial effect of the invention is that it has the advantage of large absorption range, achieves the purpose of high conversion efficiency, and has market competitiveness with low manufacturing cost.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the absorption spectrum graph of existing single-order planar solar cell

Fig. 2 is a partially enlarged sectional view of the present invention

Fig. 3 is the partially enlarged sectional view of increasing buffer layer of the present invention

Fig. 4 is the schematic diagram of the light source absorption process of the photoelectric conversion layer of the present invention

Fig. 5 is the schematic diagram of energy gap scope of the present invention

Fig. 6 is the absorption coefficient graph of SiN, a-Si and SiSn of the present invention

Explanation of symbols in the figure:

10 Substrate 20 The first penetration film

30 The first photoelectric conversion layer 30P The first P layer

30I first I layer 30N first N layer

30B first buffer layer 40 second photoelectric conversion layer

40P second P layer 40I second I layer

40N second N layer 40B second buffer layer

50 The third photoelectric conversion layer 50P The third P layer

50I third layer I 50N third layer N

50B third buffer layer 60 second through film

70 upper electrode X1 first light source

X2 second light source X3 third light source

X4 fourth light source X5 fifth light source

L1 first curve L2 second curve

L3 third curve L4 fourth curve

Detailed ways

As shown in Fig. 2, the present invention is a solar cell with multi-layer amorphous silicon thin film, which includes: a substrate 10, which can transmit light;

A first transmissive film 20 is arranged on the substrate 10 and can transmit light;

A first photoelectric conversion layer 30 is formed by stacking a first P layer 30P, a first I layer 30I and a first N layer 30N, wherein the first I layer 30I is made of a-SiN, The first photoelectric conversion layer 30 is disposed on the first transparent film 20, and the adjustable energy bandwidth is between 1.7ev and 2.3ev according to the ratio of process gas SiH4/NH3;

A second photoelectric conversion layer 40 is formed by stacking a second P layer 40P, a second I layer 40I and a second N layer 40N, wherein the second I layer 40I is made of a-Si (amorphous silicon, That is, amorphous silicon), and the second photoelectric conversion layer 40 is arranged on the first photoelectric conversion layer 30, and according to the ratio of process gas SiH4/H2, the adjustable energy bandwidth is generally about 1.7 eV;

A third photoelectric conversion layer 50 is formed by stacking a third P layer 50P, a third I layer 50I and a third N layer 50N, wherein the third I layer 50I is made of a-SiSn, and The third photoelectric conversion layer 50 is disposed on the second photoelectric conversion layer 40, and by sputtering or vapor deposition, the adjustable energy bandwidth is between 0.08ev and 1.1ev, and the first The energy gap of the photoelectric conversion layer 30 is greater than the energy gap of the second photoelectric conversion layer 40, and the energy gap of the second photoelectric conversion layer 40 is greater than the energy gap of the third photoelectric conversion layer 50;

A second transmissive film 60 is arranged above the third photoelectric conversion layer 50 and can transmit light;

An upper electrode 70 is disposed on the second TX film 60 .

More specifically, the present invention utilizes a silicon compound (such as SiN, SiSn and a-Si) stacked into a multi-band structure design, which can make the energy gap (bandgap, energy gap, or translated as energy gap) range from 1.0 to Between 2.3ev, increase the spectral range and absorb light band.

As shown in Figure 3, the first, second and third photoelectric conversion layers 30, 40 and 50 can be respectively provided with a first buffer layer 30B, a second buffer layer 40B and a third buffer layer 50B to achieve The improvement of each P-layer and I-layer level further increases the open circuit voltage (Voc) and short circuit current (Isc) to achieve higher conversion efficiency.

Certainly, when the present invention is in use, the irradiation direction of the light source enters from the substrate 10 (as shown by the arrows in FIG. 2 and FIG. 3 ).

Now give a simplified embodiment to explain the working principle of the present invention, as shown in Figure 4, assuming that sunlight is simplified to be synthesized by light of five different wavelengths, it can be respectively set as:

The first light source X1 has a wavelength of 0.8 μm;

The second light source X2 has a wavelength of 0.7 μm;

The third light source X3 has a wavelength of 0.6 μm;

The fourth light source X4, with a wavelength of 0.5 μm;

The fifth light source X5 has a wavelength of 0.4 μm.

When the first light source X1, the second light source X2, the third light source X3, the fourth light source X4 and the fifth light source X5 all enter the present invention, they first penetrate the light-transmissible substrate 10 and the first transmissive film 20 , and then enter the first photoelectric conversion layer 30, assuming that the energy gap of the first photoelectric conversion layer 30 is 2.3eV, therefore, only the energy generated by the fourth ray X4 and the fifth ray X5 is sufficiently greater than 2.3eV While generating electricity, the rest of the first light source X1, the second light source X2, and the third light source X3 continue to move forward. When entering the second photoelectric conversion layer 40 , assuming that the energy gap of the second photoelectric conversion layer 40 is 1.7 eV, only the energy generated by the third light X3 is greater than 1.7 eV to make the second photoelectric conversion layer 40 generate electricity. After that, only the first light source X1 and the second light source X2 enter the third photoelectric conversion layer 50. Assuming that the energy gap of the third photoelectric conversion layer 50 is 1.0 eV, only the energy generated by the second light X2 is greater than 1.0 eV Then, the third photoelectric conversion layer 50 generates electricity. Finally, only the first light source X1 is not absorbed but reflected. In other words, using the multi-gap design of the first photoelectric conversion layer 30 , the second photoelectric conversion layer 40 and the third photoelectric conversion layer 50 of the present invention, light source absorption conversion in a specific wavelength range can be performed for different wavelengths. In particular, the related materials (SiN, a-Si and SiSn) of the present invention are easier to obtain, lower in cost and wider in energy gap range than traditional GaInP, GaAs and Ge.

Figure 5 is a schematic diagram of the energy gap distribution of the present invention, where Ef represents the Fermi level, Ev represents the valence band, and Ec represents the conduction band. And Fig. 6 shows different distribution states of absorption coefficient curves (the first curve L1, the second curve L2 and the third curve L3 are the absorption spectrum curves of SiN, a-Si and SiSn respectively, and the fourth curve L4 is the absorption spectrum curve of sunlight spectral curve), the energy gaps of SiN, a-Si and SiSn are between 1.1 and 2.3eV, and they can respectively absorb each light band of sunlight in the range of absorption, and the present invention integrates them respectively in the first In a photoelectric conversion layer 30, the second photoelectric conversion layer 40 and the third photoelectric conversion layer 50, each light band of sunlight can be absorbed and converted in each layer respectively, so as to achieve a large-scale high absorption effect (shown in Fig. 6, it can be seen that the absorption spectrum curves of SiN, a-Si and SiSn can be close to the spectrum curve of sunlight after integration).

In summary, advantages and effects of the present invention can be summarized as:

1. Large absorption range. Existing solar cells, whether they are single-level or stacked, have certain limitations in the absorption effect, and the photoelectric conversion layer made of SiN, a-Si and SiSn in the present invention has an energy gap of 1.0-2.3 eV. For most of the solar light bands, the absorption effect can be achieved, so the absorption range is large.

2. High conversion efficiency. Since the energy gap of the solar cell with the amorphous silicon multi-layer thin film of the present invention reaches between 1.0 and 2.3 eV, and the range of light bands absorbed is large, its conversion efficiency can be effectively improved. A buffer layer can effectively improve the p/i step surface, thereby increasing the open circuit voltage and short circuit current, and achieving higher conversion efficiency.

3. The manufacturing cost is low. Since the photoelectric conversion layer composed of SiN, a-Si and SiSn is used in this case, the materials are easier to obtain, so the manufacturing cost is lower than that of traditional GaInP, GaAs and Ge solar cells.

Claims (3)

1. A solar cell with an amorphous silicon multi-layer thin film, characterized in that it comprises: A substrate, which can transmit light; a first transparent electrical film, which is arranged on the substrate and can transmit light; A first photoelectric conversion layer is formed by stacking a first P layer, a first I layer and a first N layer, wherein the first I layer is made of a-SiN, and the first photoelectric conversion layer The layer is arranged on the first transparent electric film, and the adjustable energy bandwidth is between 1.7ev and 2.3ev; A second photoelectric conversion layer is formed by stacking a second P layer, a second I layer and a second N layer, wherein the second I layer is made of a-Si, and the second photoelectric The conversion layer is arranged on the first photoelectric conversion layer, and the adjustable energy bandwidth is about 1.7 eV; A third photoelectric conversion layer is formed by stacking a third P layer, a third I layer and a third N layer, wherein the third I layer is made of a-SiSn, and the third photoelectric conversion layer The layer is arranged on the second photoelectric conversion layer, and the adjustable energy bandwidth is between 0.08ev and 1.1ev, and the energy gap of the first photoelectric conversion layer is greater than the energy gap of the second photoelectric conversion layer Gap, and the energy gap of the second photoelectric conversion layer is greater than the energy gap of the third photoelectric conversion layer; A second transmissive film is arranged above the third photoelectric conversion layer and can transmit light; An upper electrode is arranged on the second TT film. 2. The solar cell with amorphous silicon multi-layer thin film according to claim 1, characterized in that: the first, second and third photoelectric conversion layers can be respectively provided with a first buffer layer, a first Two buffer layers and a third buffer layer, and the energy gap of the first photoelectric conversion layer is larger than the energy gap of the second photoelectric conversion layer, and the energy gap of the second photoelectric conversion layer is larger than the third photoelectric conversion layer. Layer gap. 3. The solar cell with amorphous silicon multi-layer thin film according to claim 1, characterized in that: The energy bandwidth of the first photoelectric conversion layer is modulated by the ratio of process gas SiH4/NH3; The energy bandwidth of the second photoelectric conversion layer is modulated by the ratio of process gas SiH4/H2; The energy bandwidth of the third photoelectric conversion layer is modulated by sputtering or vapor deposition.

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