Radiation resistant solar cell

Abstract

A radiation-resistant solar cell includes a first cell comprising: a first P-type base region and a first N-type emitter region, which together form a first PN junction; a quantum well located within the first P-type base region and positioned away from the interface between the first P-type base region and the first N-type emitter region forming the first PN junction; and P-type doping in the quantum well region, with the surface doping concentration increasing in a direction away from the first PN junction interface, thereby forming an auxiliary built-in electric field within the quantum well region. The direction of this auxiliary built-in electric field is configured to promote the drift of photogenerated minority carriers towards the first PN junction interface. The quantum well configuration of the solar cell is optimized to meet the dual requirements of high conversion efficiency and high radiation resistance.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a radiation-resistant solar cell. Background Technology

[0002] In the field of solar cells, photocurrent matching when multi-junction cells are connected in series is an important research direction for improving conversion efficiency in the photovoltaic industry.

[0003] To optimize current matching conditions, existing technologies incorporate multiple quantum well (MQW) structures into solar cells. By adjusting the composition and thickness of the quantum wells, the bandgap of sub-cells can be precisely controlled to enhance light absorption, thereby maximizing output current and improving overall conversion efficiency. In device structure design, multiple quantum wells are typically placed near the PN junction. Utilizing the built-in electric field formed by carrier diffusion in the PN junction, the drift motion of photogenerated carriers in the quantum wells can be promoted, effectively improving the collection efficiency of photogenerated minority carriers, and thus enhancing the cell conversion efficiency.

[0004] However, particle radiation in real-world operating environments poses challenges to the performance of solar cells. Existing research shows that although quantum well structures can significantly improve cell output current and conversion efficiency, their radiation resistance is significantly inferior to that of conventional solar cells, specifically manifested in a significant decrease in the fill factor (FF) after irradiation. Particle irradiation experiments have revealed that quantum well structures exhibit a severe carrier removal (CR) effect: in the p-type region, the initial quasi-intrinsic background of the quantum well region transforms into an n-type background due to particle radiation, leading to a substantial reduction or even complete collapse of the built-in electric field width between the emitter and base. This failure of the built-in electric field severely hinders the effective collection of photogenerated carriers in the emitter and base regions near the PN junction, becoming a key technical bottleneck restricting the application of quantum well structures under irradiation conditions.

[0005] Therefore, it is urgent to optimize the radiation resistance of quantum well structures, while maintaining their current enhancement advantage, to solve the problems of built-in electric field collapse and carrier collection failure after irradiation, so as to meet the dual requirements of high conversion efficiency and high radiation resistance. Summary of the Invention

[0006] The purpose of this invention is to provide a radiation-resistant solar cell. The technical problem to be solved is how to optimize the quantum well configuration of the solar cell to meet the dual requirements of high conversion efficiency and high radiation resistance.

[0007] To achieve the above objectives, the solution of the present invention is as follows:

[0008] A radiation-resistant solar cell includes a first cell, the first cell comprising:

[0009] The first P-type base region and the first N-type emitter region together form the first PN junction;

[0010] The quantum well is located within the first P-type base region and is far from the first PN junction interface formed between the first P-type base region and the first N-type emitter region.

[0011] P-type doping is applied to the quantum well region, with the surface doping concentration increasing in a direction away from the first PN junction interface, thereby forming an auxiliary built-in electric field in the quantum well region. The direction of this auxiliary built-in electric field is configured to promote the drift of photogenerated minority carriers towards the first PN junction interface.

[0012] Furthermore, the first battery is a gallium arsenide solar cell.

[0013] Furthermore, the first cell is used to form one of the junctions in a multi-junction solar cell.

[0014] Furthermore, the quantum well is at least 500 nanometers away from the interface of the first PN junction.

[0015] Furthermore, the quantum well is a multi-quantum-well structure, comprising periodically alternating In... x Ga 1-x As well layer and GaAs 1-y P y Layers.

[0016] Furthermore, in In x Ga 1-x As well layer and GaAs 1-y P y The barrier layers are growing in a periodic, alternating pattern:

[0017] The number of cycles ranges from 10 to 150 pairs;

[0018] 0.05≤x≤0.3, 0.05≤y≤0.3;

[0019] In x Ga 1-x The thickness of the As well layer is 3 nanometers to 15 nanometers;

[0020] GaAs 1-y P y The thickness of the barrier layer ranges from 3 nanometers to 30 nanometers.

[0021] Furthermore, the P-type doping is Zn doping.

[0022] Furthermore, the surface concentration of the P-type doping increases in a gradient along the direction away from the first PN junction interface.

[0023] Furthermore, the quantum well is a multi-quantum-well structure comprising alternating stacked well layers and barrier layers;

[0024] From the side closest to the first PN junction interface to the side furthest away, the p-type doping concentration of the well layer ranges from (0.5-3)×10⁻⁶. 16 cm -2 The gradient increases to (0.5-3)×10 17 cm -2 The surface doping concentration of the P-type doped barrier layer ranges from (0.5-3)×10⁻⁶. 17 cm -2 The gradient increases to (0.5-1.5)×10 18 cm -2 .

[0025] Furthermore, it also includes a back electric field layer disposed below the first P-type base region, wherein the back electric field layer is Al z Ga 1-z As layer, where 0.3≤z≤1.

[0026] After adopting the above solution, the beneficial effects of the present invention are as follows:

[0027] (1) The quantum well is placed in the first P-type base region at a position far away from the first PN junction interface, so that it is far away from the first PN junction interface which is extremely sensitive to electric field under high irradiation environment. This effectively alleviates the disturbance effect of the CR effect generated after irradiation of the MQW region on the main built-in electric field.

[0028] (2) After setting the quantum well away from the first PN junction interface, in order to enhance the collection capability of photogenerated carriers in the MQW region, this scheme introduces P-type doping into the quantum well region and increases its concentration in the direction away from the PN junction interface, thereby constructing a direction-specific auxiliary built-in electric field inside the quantum well, providing directional drift driving force for these carriers, actively and quickly bringing them to the PN junction, achieving efficient collection, compensating for the potential decrease in collection efficiency caused by position adjustment, ensuring that the additional photocurrent contributed by the quantum well extended spectrum can be effectively utilized, and ensuring that the radiation-resistant design does not sacrifice the initial conversion efficiency. Attached Figure Description

[0029] Figure 1 This is a structural diagram of Example 1;

[0030] Figure 2 This is a comparison chart of FF decay data after irradiation.

[0031] Labeling explanation: 1-First cell, 2-First P-type base region, 3-First N-type emitter region, 4-First PN junction interface. Detailed Implementation

[0032] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Embodiments of the invention will now be described in full with reference to the accompanying drawings. It should be noted that the invention may be implemented in various forms and is not limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0034] Unless otherwise expressly defined, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" in the claims, description, and accompanying drawings of this invention is merely for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific scope of protection of this invention.

[0035] This invention provides a radiation-resistant solar cell, including a first cell 1. Specifically, in this embodiment, the first cell 1 is a GaAs cell (gallium arsenide solar cell). The first cell 1 includes:

[0036] The first P-type base region 2 and the first N-type emitter region 3 together form the first PN junction;

[0037] The quantum well is located within the first P-type base region 2 and is positioned far from the first PN junction interface 4 formed between the first P-type base region 2 and the first N-type emitter region 3. This position keeps it away from the first PN junction interface, which is extremely sensitive to electric fields, under high irradiation conditions. This effectively mitigates the disturbance effect of the CR effect generated after irradiation of the MQW region on the main built-in electric field.

[0038] P-type doping is applied to the quantum well region, with the surface doping concentration increasing in a direction away from the first PN junction interface 4. This creates an auxiliary built-in electric field within the quantum well region. The direction of this auxiliary built-in electric field is configured to promote the drift of photogenerated minority carriers towards the first PN junction interface 4, providing a directional drift driving force for these photogenerated minority carriers. This actively and rapidly brings them to the PN junction interface, achieving efficient collection. This compensates for the potential decrease in collection efficiency caused by position adjustment and ensures that the additional photocurrent contributed by the extended spectrum of the quantum well can be effectively utilized, so that the radiation-resistant design does not come at the expense of initial conversion efficiency.

[0039] In a specific embodiment, the first battery 1 can be used to form one of the junctions in a multi-junction solar cell, or it can be used as a single-junction solar cell itself.

[0040] In a preferred embodiment, the quantum well is at least 500 nanometers away from the first PN junction interface 4. This specific range ensures that there is a sufficient buffer distance between the quantum well defect region and the PN junction depletion region, which can effectively block the interference of irradiation defects on the main electric field, while avoiding the problem that the probability of recombination of photogenerated carriers during transport will increase dramatically due to excessive distance.

[0041] In a preferred embodiment, the quantum well is a multi-quantum well structure, comprising periodically alternating In... x Ga 1-x As well layer and GaAs 1-y P y Layers, and in In x Ga 1-x As well layer and GaAs 1-y P y In the periodic alternating growth of barrier layers: the number of cycles ranges from 10 to 150 pairs; 0.05 ≤ x ≤ 0.3, 0.05 ≤ y ≤ 0.3; In x Ga 1-x The thickness of the As well layer is 3 nanometers to 15 nanometers; GaAs 1- y P y The thickness of the barrier layer ranges from 3 nanometers to 30 nanometers. Firstly, it ensures that the effective absorption bandgap of the quantum well is tunable, allowing for flexible matching of the top cell current and optimized spectral utilization when used as a junction in a multi-junction solar cell. Secondly, while achieving the desired narrow bandgap, the strain compensation design (In enlarges the lattice and P shrinks the lattice) effectively suppresses through-dislocations caused by lattice mismatch, improving the crystal quality of the quantum well region and enhancing radiation resistance from the material's fundamental source.

[0042] In a preferred embodiment, the p-type doping surface concentration increases in a gradient away from the first PN junction interface 4. The quantum well is a multi-quantum-well structure comprising alternating stacked well and barrier layers; from the side closest to the first PN junction interface 4 to the side furthest away, the p-type doping surface concentration of the well layers increases from (0.5-3)×10⁻⁶. 16 cm -2 The gradient increases to (0.5-3)×10 17 cm -2 The doping concentration of the P-type doped surface of the barrier layer ranges from (0.5-3)×10⁻⁶. 17 cm -2 The gradient increases to (0.5-1.5)×10 18 cm -2 This provides an optimal range for high-efficiency photoelectric conversion and stable material growth.

[0043] It also includes a back electric field layer disposed below the first P-type base region 2, wherein the back electric field layer is Alz Ga 1-z As layer, where 0.3≤z≤1.

[0044] Specifically, the P-type doping is Zn doping. Choosing Zn is beneficial for achieving a high concentration and a steep surface doping concentration distribution, ensuring the feasibility and repeatability of the gradient doping process.

[0045] The following is a more specific example:

[0046] Taking the dual-junction GaInP / GaAs (InGaAs / GaAsP MQW) solar cell as an example, the specific implementation method is described.

[0047] Example 1, combined with Figure 1 As shown:

[0048] The first cell 1 is used to form a single-junction cell in a double-junction GaInP / GaAs (InGaAs / GaAsP MQW) solar cell. The double-junction GaInP / GaAs (InGaAs / GaAsP MQW) solar cell includes, from bottom to top: an n-type GaAs substrate, a GaAs buffer layer, a first tunnel junction, a DBR reflective layer, a GaAs (InGaAs / GaAsP MQW) cell, a second tunnel junction, a GaInP cell, and a GaAs cap layer.

[0049] GaAs (InGaAs / GaAsP MQW) cells grown from bottom to top with 50nm Al 0.5 Ga 0.5 As BSF, Zn surface doping concentration 2×10 18 cm -2 ; 50nm GaAs surface doping concentration 1×10 18 cm -2 ; 80 pairs of MQW, In x Ga 1-x As well layer (x=0.1, thickness: 8nm), GaAs 1-y P y The barrier layer (y=0.2, thickness: 8nm) is doped with Zn by MQW, with the Zn doping concentration gradually decreasing from bottom to top. The well layer doping concentration starts from 1×10⁻⁶. 17 cm -2 Reduced to 1×10 16 cm -2 The barrier layer doping consists of 1×10 18 cm -2 Reduced to 1×10 17 cm -2 ; 1.6μm GaAs, Zn surface doping concentration from bottom to top increases from 1×10 17 cm -2Reduced to 5×10 16 cm -2 Si-doped GaAs emitter, 100 nm thick, surface doping concentration 2 × 10⁻⁶ 18 ; 100nm Al 0.52 In 0.48 P-window layer, Si surface doping concentration 1×10⁻⁶ 18 cm -2 .

[0050] The structural parameter ranges for GaAs batteries are as follows:

[0051] GaAs (InGaAs / GaAsP MQW) cells are grown from bottom to top using Al z Ga 1-z As (0.3≤z≤1, thickness: 15-100nm) back electric field layer (BSF), Zn surface doping concentration 1×10 18 cm -2 Up to 5×10 18 cm -2 The p-type GaAs base region (thickness: 1μm-3μm) does not contain the MQW portion, and the surface doping concentration is 1×10⁻⁶. 16 cm -2 Up to 1×10 18 cm -2 MQW can be inserted at any position in the GaAs base region away from the PN junction, ranging from 500 nm to the BSF; the MQW structure contains In x Ga 1-x As well layer (0.05≤X≤0.3, thickness: 3-15nm), GaAs 1-y P y Barrier layer (0.05≤y≤0.3, thickness: 3-30nm), MQW pair number: 10 to 150 pairs, MQW doped with Zn, the Zn surface doping concentration gradually decreases from bottom to top, and the well layer doping is (0.5-3)×10 17 cm -2 Reduced to (0.5-3)×10 16 cm -2 The barrier layer doping consists of (0.5-1.5)×10⁻⁶ layers. 18 cm -2 Reduced to (0.5-3)×10 17 cm -2 .

[0052] Comparative Example 1:

[0053] The double-junction GaInP / GaAs (InGaAs / GaAsP MQW) solar cell, from bottom to top, comprises: an n-type GaAs substrate, a GaAs buffer layer, a first tunnel junction, a DBR reflective layer, a GaAs (InGaAs / GaAsP MQW) cell, a second tunnel junction, a GaInP cell, and a GaAs cap layer. The GaAs (InGaAs / GaAsP MQW) cell is grown from bottom to top with a 50nm Al layer. 0.5 Ga 0.5 As BSF, Zn surface doping concentration 2×10 18 cm -2 The doping concentration of the 1.6μm GaAs surface is 1×10⁻⁶ from bottom to top. 18 -1×10 17 cm -2 ; 80 pairs of MQW, In x Ga 1-x As well layer (x=0.1, thickness: 8nm), GaAs 1-y P y Barrier layer (y=0.2, thickness: 8nm), undoped Zn in MQW; Si-doped GaAs emitter, 100nm thick, surface doping concentration 2×10⁻⁶. 18 cm -2 ; 100nm Al 0.52 In 0.48 P-window layer, Si surface doping concentration 2×10⁻⁶ 18 cm -2 .

[0054] Comparative Example 2:

[0055] The double-junction GaInP / GaAs (InGaAs / GaAsP MQW) solar cell, from bottom to top, comprises: an n-type GaAs substrate, a GaAs buffer layer, a first tunnel junction, a DBR reflective layer, a GaAs (InGaAs / GaAsP MQW) cell, a second tunnel junction, a GaInP cell, and a GaAs cap layer. The GaAs (InGaAs / GaAsP MQW) cell is grown from bottom to top with a 50nm Al layer. 0.5 Ga 0.5 As BSF, Zn surface doping concentration 2×10 18 cm -2 The doping concentration of the 1.6μm GaAs surface is 1×10⁻⁶ from bottom to top. 18 -1×10 17 cm -2 ; 80 pairs of MQW, In x Ga 1-x As well layer (x=0.1, thickness: 8nm), GaAs 1-y Py Barrier layer (y=0.2, thickness: 8nm), MQW-doped Zn, well layer doped with 5×10⁻⁶ 16 cm -2 Barrier layer doping 1×10 17 cm -2 Si-doped GaAs emitter, 100 nm thick, surface doping concentration 2 × 10⁻⁶ 18 cm -2 ; 100nm Al 0.52 In 0.48 P-window layer, Si surface doping concentration 2×10⁻⁶ 18 cm -2 .

[0056] like Figure 2 As shown in the figure, experimental verification shows that under irradiation conditions of 1 MeV and 1 × 10⁻⁶ m / s, the desired effect is achieved. 15 cm -2 At flux. Comparative Example 1, based on a quantum well battery design, has its quantum well adjacent to the PN junction interface and has not undergone any doping optimization. After irradiation, the flow rate (FF) decays significantly. Comparative Example 2 introduces uniform doping into the traditional quantum well location, which can improve the conductivity and carrier transport efficiency of the quantum well region to some extent. However, its quantum well is still near the PN junction interface, failing to address the fundamental contradiction of overlapping "defect regions" and "core functional regions." After irradiation, while the FF decay is better than in Comparative Example 1, significant decay still occurs. In this embodiment, however, no significant FF decay is observed after irradiation.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the design of this case. All equivalent changes made based on the key design features of this case shall fall within the protection scope of this case.

Claims

1. A radiation-resistant solar cell, characterized in that, Including a first battery (1), the first battery (1) includes: The first P-type base region (2) and the first N-type emitter region (3) together form the first PN junction; The quantum well is located within the first P-type base region (2) and is far from the first PN junction interface (4) formed between the first P-type base region (2) and the first N-type emitter region (3). P-type doping is doped in the quantum well region, and its surface doping concentration increases in a direction away from the first PN junction interface (4), thereby forming an auxiliary built-in electric field in the quantum well region. The direction of the auxiliary built-in electric field is configured to promote the drift of photogenerated minority carriers to the first PN junction interface (4). The quantum well is at least 500 nanometers away from the first PN junction interface (4); The quantum well is a multi-quantum well structure comprising alternating stacked well layers and barrier layers; From the side closest to the first PN junction interface (4) to the side furthest away, the surface doping concentration of the P-type doped well layer ranges from (0.5-3)×10⁻⁶. 16 cm -2 The gradient increases to (0.5-3)×10 17 cm -2 The surface doping concentration of the P-type doped barrier layer ranges from (0.5-3)×10⁻⁶. 17 cm -2 The gradient increases to (0.5-1.5)×10 18 cm -2 .

2. The radiation-resistant solar cell as described in claim 1, characterized in that: The first battery (1) is a gallium arsenide solar cell.

3. The radiation-resistant solar cell as described in claim 1, characterized in that: The first cell (1) is used to form one of the junctions in a multi-junction solar cell.

4. The radiation-resistant solar cell as described in claim 1, characterized in that: The quantum well is a multi-quantum well structure, including periodically alternating In... x Ga 1-x As well layer and GaAs 1-y P y Layers.

5. The radiation-resistant solar cell as described in claim 4, characterized in that: In x Ga 1-x As well layer and GaAs 1-y P y The barrier layers are growing in a periodic, alternating pattern: The number of cycles ranges from 10 to 150 pairs; 0.05≤x≤0.3, 0.05≤y≤0.3; In x Ga 1-x The thickness of the As well layer is 3 nanometers to 15 nanometers; GaAs 1-y P y The thickness of the barrier layer ranges from 3 nanometers to 30 nanometers.

6. The radiation-resistant solar cell as described in claim 1, characterized in that: The P-type doping is Zn doping.

7. The radiation-resistant solar cell as described in claim 1, characterized in that: The surface concentration of the P-type doping increases in a gradient along the direction away from the first PN junction interface (4).

8. The radiation-resistant solar cell as described in claim 1, characterized in that: It also includes a back electric field layer disposed below the first P-type base region (2), wherein the back electric field layer is Al Z Ga 1-Z As layer, where 0.3≤z≤1.

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