CN101499493A - Three-junction solar cell - Google Patents

Abstract

Translated fromChinese

本发明提供了一种含有量子阱结构的太阳能电池，该电池结构为：从下至上包括背电极；p型锗衬底与n型锗外延层组成的底电池；n型GaAs层过渡层；下隧穿结；p型GaAs层、量子阱结构与n型GaAs层组成的中间电池；上隧穿结；p型GaInP层与n型GaInP层组成的顶电池；减反射膜和上电极，其中量子阱结构分为由三五簇半导体材料制成的量子阱层和势垒层，该太阳能电池能够扩展中间电池的吸收光谱，改善三个子电池间的电流匹配，提高电池的转换效率。

The invention provides a solar cell with a quantum well structure, the cell structure is: from bottom to top including a back electrode; a bottom cell composed of a p-type germanium substrate and an n-type germanium epitaxial layer; an n-type GaAs layer transition layer; Tunnel junction; middle cell composed of p-type GaAs layer, quantum well structure and n-type GaAs layer; upper tunnel junction; top cell composed of p-type GaInP layer and n-type GaInP layer; antireflection film and upper electrode, in which quantum The well structure is divided into a quantum well layer and a barrier layer made of three or five clusters of semiconductor materials. The solar cell can expand the absorption spectrum of the middle cell, improve the current matching between the three sub-cells, and improve the conversion efficiency of the cell.

Description

A kind of three-joint solar cell

One, technical field

The present invention relates to a kind of solar cell, particularly relate to a kind of solar cell that contains quantum well structure.

Two, background technology

Three knot GaInP/GaAs/Ge solar cells are present the highest solar cells of conversion efficiency in the world.But to further improve its photoelectric conversion efficiency, need to solve three bad problems of sub-battery current coupling that exist in three junction batteries.In existing three junction batteries, the electric current of middle subcell is less than top battery and end battery, cause final output current to be subject to middle subcell, make the part electric current of top battery and end battery to utilize, cause difficulty for the photoelectric conversion efficiency that further improves battery.

Three, summary of the invention

Technical problem:

The structure that the purpose of this invention is to provide a kind of improved three-joint solar cell to improve the currents match of three sub-batteries, improves the conversion efficiency of three junction batteries.

Technical scheme: technical solution of the present invention is:

A kind of three-joint solar cell, battery structure is: comprises dorsum electrode layer, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up tunnel junctions layer, top battery layers, antireflection film layer and upper electrode layer, wherein:

End battery layers is made up of p type Ge single crystalline substrate and n type Ge epitaxial loayer from bottom to up;

Transition zone is n type GaAs layer a;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a and heavily doped p type GaAs layer a from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer, n type GaAs layer b and be clipped in described p type GaAs layer and n type GaAs layer b in the middle of quantum well structure form, described quantum well structure is divided into quantum well layer and barrier layer, and quantum well layer and barrier layer are made by three or five bunches of semi-conducting materials;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b and heavily doped p type GaAs layer b from bottom to up;

The top battery layers is made up of p type GaInP layer and n type GaInP layer from bottom to up.

Wherein, three or five bunches of semi-conducting materials making quantum well layer are GaInP, GaAs, InGaAs, GaAlP, AlGaAs or GaAsP, and three or five bunches of semi-conducting materials making barrier layer are GaInP, GaAs, InGaAs, GaAlP, AlGaAs or GaAsP.

Quantum well structure is single quantum or multi-quantum pit structure, and in the quantum well structure, the thickness of quantum well layer is the 1-200 nanometer, and the thickness of barrier layer is the 1-300 nanometer.

Back electrode, antireflective coating and top electrode all prepare by vacuum evaporation method.

Antireflective coating is oxide, nitride or fluoride film.

Beneficial effect:

The present invention considers the band structure of quantum well uniqueness and the characteristics that the inner generation of film strain reaches lattice match, utilize quantum well structure lattice coupling and the adjustable characteristic of effective bandwidth easily, quantum well structure is incorporated in the sub-battery of middle GaAs of three-joint solar cell, the absorption spectrum of expansion middle subcell, increase the electric current of middle subcell, improve currents match, improve conversion efficiency.

The three-joint solar cell of quantum well structure that has of the present invention is compared with the traditional three-joint solar cell that does not contain the quantum well structure, in battery operated process, utilize the narrow band gap in the quantum well structure, the absorption spectrum of middle subcell is expanded to the long wave direction, increased photogenerated current, improved the currents match between three sub-batteries, improved the photoelectric conversion efficiency of three junction batteries, made the photoelectric conversion efficiency of three junction batteries surpass 30%.Compare with existing three-joint solar cell, the conversion efficiency of this novel three junction batteries has improved 5%.。

And it is compatible fully with the preparation technology of the traditional three-joint solar cell that does not contain the quantum well structure to contain the three-joint solar cell of quantum well structure, can directly finish whole processing steps on existing equipment.

Four, description of drawings

Fig. 1 is the structural representation of solar cell of the present invention.

Among the figure: the 1-dorsum electrode layer; 2-p type Ge single crystalline substrate; 3-n type Ge epitaxial loayer; 4-n type GaAs layer a; The heavily doped n type of 5-GaAs layer a; The heavily doped p type of 6-GaAs layer a; 7-p type GaAs layer; The 8-quantum well structure; 9-n type GaAs layer b; The heavily doped n type of 10-GaAs layer b; The heavily doped p type of 11-GaAs layer b; 12-p type GaInP layer; 13-n type GaInP layer; The 14-antireflection film layer; The 15-upper electrode layer;

Five, embodiment

Following examples are more of the present invention giving an example, and should not regarded as limitation of the invention.

Embodiment 1:

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n type Geepitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 30 cycles, wherein InGaAs is as quantum well layer, thickness is 15 nanometers, GaInP is as barrier layer, and thickness is 21 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is a silica membrane;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 2:

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n type Geepitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 20 cycles, wherein InGaAs is as quantum well layer, thickness is 10 nanometers, GaAs is as barrier layer, and thickness is 12 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflective coating 14 is a titanium deoxid film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 3:

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n type Geepitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into a quantum well layer and a barrier layer, wherein InGaAs is as quantum well layer, thickness is 15 nanometers, GaInP is as barrier layer, and thickness is 8 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is a silicon nitride film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 4

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n type Geepitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 10 cycles, wherein InGaAs is as quantum well layer, thickness is 5 nanometers, GaInP is as barrier layer, and thickness is 7 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is a magnesium fluoride film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 5:

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n typeGe epitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 30 cycles, wherein InGaAs is as quantum well layer, thickness is 15 nanometers, GaInP is as barrier layer, and thickness is 21 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is an aluminum oxide film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 6:

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n typeGe epitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 20 cycles, wherein InGaAs is as quantum well layer, thickness is 10 nanometers, GaAs is as barrier layer, and thickness is 12 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflective coating 14 is a zinc-oxide film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 7:

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n typeGe epitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into a quantum well layer and a barrier layer, wherein InGaAs is as quantum well layer, thickness is 15 nanometers, GaInP is as barrier layer, and thickness is 8 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is an aluminium nitride film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 8

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n typeGe epitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 10 cycles, wherein InGaAs is as quantum well layer, thickness is 5 nanometers, GaInP is as barrier layer, and thickness is 7 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is a titanium nitride membrane;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 9

A kind of solar cell is characterized in that battery structure is: comprises dorsum electrode layer 1, end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, goes up the tunnel junctions layer, and top battery layers,antireflection film layer 14 andupper electrode layer 15, wherein:

End battery layers is made up of p type Ge single crystalline substrate 2 and n typeGe epitaxial loayer 3 from bottom to up;

Transition zone is n type GaAs layer a4;

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a5 and heavily doped p type GaAs layer a6 from bottom to up;

The intermediate cell layer from bottom to up by p type GaAs layer 7 with n type GaAs layer b9 and be clipped in described p type GaAs layer 7 and form with thequantum well structure 8 in the middle of the n type GaAs layer b9, describedquantum well structure 8 is divided into quantum well layer and barrier layer, have 10 cycles, wherein InGaAs is as quantum well layer, thickness is 5 nanometers, GaInP is as barrier layer, and thickness is 7 nanometers;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b10 and heavily doped p type GaAs layer b11 from bottom to up;

The top battery layers is made up of ptype GaInP layer 12 and ntype GaInP layer 13 from bottom to up;

Antireflection film layer 14 is the zinc fluoride film;

Above-mentioned dorsum electrode layer 1,antireflection film layer 14 andupper electrode layer 15 all prepare by vacuum evaporation method.

Embodiment 10

The step of the three-joint solar cell among the preparation embodiment 1 is:

At first, growing n-type Ge epitaxial loayer on p type Ge single crystalline substrate; Growth one deck n type GaAs is as transition zone on n type Ge epitaxial loayer; Heavily doped n type of epitaxial growth and p type GaAs are as following tunnel junctions again; The p type GaAs of the intermediate cell of on following tunnel junctions, growing successively sequentially, InGaAs/GaInP quantum well structure, n type GaAs, wherein InGaAs is as quantum well layer, and thickness is 15 nanometers, and GaInP is as barrier layer, and thickness is 21 nanometers; The heavily doped n type of growing and p type GaAs are as last tunnel junctions; The p type GaInP and the n type GaInP of top battery sequentially grow on last tunnel junctions; Adopt the method for vacuum evaporation to plate the layer of silicon dioxide film as antireflective coating at upper surface; Method at battery upper surface and the back side by vacuum evaporation prepares top electrode and back electrode.

Embodiment 11

The step of the three-joint solar cell among the preparation embodiment 2 is:

At first, growing n-type epitaxial loayer on p type Ge single crystalline substrate; Growth one deck n type GaAs is as transition zone on n type epitaxial loayer; Heavily doped n type of epitaxial growth and p type GaAs are as following tunnel junctions again; The p type GaAs of the intermediate cell of on following tunnel junctions, growing sequentially, InGaAs/GaAs quantum well structure, n type GaAs, wherein quantum well structure is divided into quantum well layer and barrier layer, have 20 cycles, InGaAs is as quantum well layer, thickness is 10 nanometers, and GaAs is as barrier layer, and thickness is 12 nanometers; The heavily doped n type of growing and p type GaAs are as last tunnel junctions; The p type GaInP and the n type GaInP of top battery sequentially grow on last tunnel junctions; Adopt the method for vacuum evaporation to plate the layer of silicon dioxide film as antireflective coating at upper surface; Method at battery upper surface and the back side by vacuum evaporation prepares top electrode and back electrode.

Claims (6)

1. three-joint solar cell, it is characterized in that battery structure is: comprise dorsum electrode layer (1), end battery layers, transition zone, following tunnel junctions layer, intermediate cell layer from bottom to up, go up tunnel junctions layer, top battery layers, antireflection film layer (14) and upper electrode layer (15), wherein:

End battery layers is made up of p type Ge single crystalline substrate (2) and n type Ge epitaxial loayer (3) from bottom to up;

Transition zone is n type GaAs layer a (4);

Following tunnel junctions layer is made up of heavily doped n type GaAs layer a (5) and heavily doped p type GaAs layer a (6) from bottom to up;

The intermediate cell layer is made up of p type GaAs layer (7), n type GaAs layer b (9) and the quantum well structure (8) that is clipped in the middle of described p type GaAs layer (7) and the n type GaAs layer b (9) from bottom to up, described quantum well structure (8) is divided into quantum well layer and barrier layer, and quantum well layer and barrier layer are made by three or five bunches of semi-conducting materials;

Last tunnel junctions layer is made up of heavily doped n type GaAs layer b (10) and heavily doped p type GaAs layer b (11) from bottom to up;

The top battery layers is made up of p type GaInP layer (12) and n type GaInP layer (13) from bottom to up.

2. three-joint solar cell according to claim 1, three or five bunches of semi-conducting materials that it is characterized in that making quantum well layer are GaInP, GaAs, InGaAs, GaAlP, AlGaAs or GaAsP, and three or five bunches of semi-conducting materials making barrier layer are GaInP, GaAs, InGaAs, GaAlP, AlGaAs or GaAsP.

3. three-joint solar cell according to claim 1 is characterized in that described quantum well structure (8) is single quantum or multi-quantum pit structure.

4. three-joint solar cell according to claim 1 is characterized in that in the described quantum well structure (8), the thickness of quantum well layer is the 1-200 nanometer, and the thickness of barrier layer is the 1-300 nanometer.

5. three-joint solar cell according to claim 1 is characterized in that described dorsum electrode layer (1), antireflection film layer (14) and upper electrode layer (15) all prepare by vacuum evaporation method.

6. three-joint solar cell according to claim 1 is characterized in that described antireflection film layer (8) is oxide, nitride or fluoride film.

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