阅读说明：本技术 一种柔性氮化物薄膜太阳能电池及制作方法 (flexible nitride thin-film solar cell and manufacturing method thereof ) 是由 马亮 于 2018-05-31 设计创作，主要内容包括：本发明涉及光伏电池及其制造技术领域,尤其涉及一种柔性氮化物薄膜太阳能电池及制作方法。该电池包括自下而上依次设置的支撑衬底、背电极、氮化物外延层和前电极,所述背电极包括第一预应力层。该制作方法通过在衬底晶圆的上表面制备具有第一预应力层的背电极,其中,背电极内设有第一预应力层；然后在背电极的上表面固定支撑衬底；通过机械剥离将所述氮化物外延层与牺牲层之间分离,并在分离后的所述氮化物外延层上依次制备前电极和抗反射层。该电池的吸收系数和能量转换率高、重量轻并可弯曲延展,其背电极能作为预应力强化层,既加固电池结构,又能在制备时提供足够大的剥离应力,且在电池制作完成后无需额外将预应力强化层清除。(The invention relates to the technical field of photovoltaic cells and manufacturing thereof, in particular to a flexible nitride thin-film solar cell and a manufacturing method thereof. The battery comprises a supporting substrate, a back electrode, a nitride epitaxial layer and a front electrode which are sequentially arranged from bottom to top, wherein the back electrode comprises a first pre-stress layer. The manufacturing method comprises the steps of preparing a back electrode with a first pre-stress layer on the upper surface of a substrate wafer, wherein the first pre-stress layer is arranged in the back electrode; then fixing a support substrate on the upper surface of the back electrode; and separating the nitride epitaxial layer from the sacrificial layer through mechanical stripping, and sequentially preparing a front electrode and an anti-reflection layer on the separated nitride epitaxial layer. The battery has high absorption coefficient and energy conversion rate, light weight and flexibility and extension, the back electrode of the battery can be used as a prestress strengthening layer, the battery structure is strengthened, enough peeling stress can be provided during preparation, and the prestress strengthening layer does not need to be additionally removed after the battery is manufactured.)

1. The flexible nitride thin-film solar cell is characterized by comprising a supporting substrate, a back electrode, a nitride epitaxial layer and a front electrode which are sequentially arranged from bottom to top, wherein the back electrode comprises a first pre-stress layer.

2. the flexible nitride thin film solar cell of claim 1, wherein a dielectric reflective layer is disposed between the nitride epitaxial layer and the back electrode, the dielectric reflective layer comprising a plurality of reflective blocks, each reflective block being discretely distributed between the nitride epitaxial layer and the back electrode.

3. The flexible nitride thin-film solar cell according to claim 1, wherein an anti-reflection layer is provided on the front electrode.

4. the flexible nitride thin film solar cell of any one of claims 1-3, wherein the back electrode comprises an adhesion layer, the first pre-stress layer and a conductive layer connected in sequence, the adhesion layer is connected with the nitride epitaxial layer, and the conductive layer is connected with a support substrate.

5. the flexible nitride thin film solar cell of claim 4, wherein an electrode reflecting layer is arranged between the adhesion layer and the first pre-stress layer.

6. the flexible nitride thin film solar cell of claim 5, wherein the adhesion layer has at least one metal element of Ni, Pd, Mo, Pt, Cr, Ti, Ta, and W;

and/or the electrode reflection layer has at least one metal element of Ag and Al;

And/or the first pre-stress layer is provided with at least one metal element of Ni, Mo, Cr, Pd, Pt, W, Ti and Ta;

And/or the conductive layer has at least one metal element of Al, Cu, Ni, Ag, Au, and Pt.

7. The flexible nitride thin film solar cell of claim 4, wherein a barrier layer is disposed between the first pre-stress layer and the conductive layer.

8. the flexible nitride thin film solar cell of claim 7, wherein the barrier layer has at least one metal element of W, Mo, Ta, and Ti.

9. the flexible nitride thin film solar cell according to any one of claims 1 to 3, wherein the nitride epitaxial layer comprises a buffer layer, an n-type doping layer, an undoped MQWlayer, and a p-type doping layer connected in this order, the buffer layer is connected to the front electrode, and the p-type doping layer is connected to the back electrode.

10. the flexible nitride thin film solar cell of claim 9, wherein the undoped multi-quantum well layer comprises 1-200 pairs of periodic structures composed of In _xw Ga _yw Al _1-xw-yw N/In _xb Ga _yb Al _1-xb-yb N, each period of each periodic structure is composed of a quantum well layer In _xw Ga _yw Al _1-xw-yw N and a quantum barrier layer In _xb Ga _yb Al _1-xb-yb N, wherein xw is 0-1, yw is 0-1, xb is 0-1, yb is 0-1, xw + yw is 0-1, xb + yb is 0-1, and xw > xb.

11. the flexible nitride thin-film solar cell according to any one of claims 1 to 3, wherein the support substrate comprises a metal substrate or a polymer substrate, and when the support substrate is the polymer substrate, a through hole is formed in the support substrate, and the through hole penetrates through the polymer substrate to communicate with the back electrode or penetrate into the back electrode.

12. A manufacturing method of a flexible nitride thin film solar cell is characterized by comprising the following steps:

S1, preparing a sacrificial layer on the upper surface of the substrate wafer;

S2, preparing a nitride epitaxial layer on the upper surface of the sacrificial layer;

S3, preparing a back electrode on the upper surface of the nitride epitaxial layer, wherein a first pre-stress layer is arranged in the back electrode;

S4, fixing a support substrate on the upper surface of the back electrode;

and S5, separating the nitride epitaxial layer from the sacrificial layer, and sequentially preparing a front electrode and an anti-reflection layer on the separated nitride epitaxial layer.

13. the method for manufacturing a ceramic electronic component according to claim 12, wherein between step S3 and step S4 or between step S4 and step S5, further comprising:

S31, preparing a second pre-stress layer on the lower surface of the substrate wafer, wherein the first pre-stress layer and the second pre-stress layer respectively apply a pair of mutually opposite balanced tensile stresses to the nitride epitaxial layer.

14. The method according to claim 13, wherein the second pre-stress layer comprises at least one metal element selected from Cr, Mo, Ni, Pd, Pt, Ti, and Ta.

15. The manufacturing method according to claim 12, wherein the step S2 specifically includes:

Preparing a dielectric reflection layer on the upper surface of the nitride epitaxial layer, wherein the dielectric reflection layer comprises a plurality of reflection blocks, and each reflection block is discretely distributed between the nitride epitaxial layer and a back electrode.

16. the method of claim 12, wherein the separating of step S5 further comprises removing edges of the nitride epitaxial layer by an etching process to form a step structure between the edges of the nitride epitaxial layer and the sacrificial layer.

17. the manufacturing method according to any one of claims 12 to 16, wherein the step S3 specifically includes:

and sequentially preparing an adhesion layer, an electrode reflection layer, the first pre-stress layer, a barrier layer and a conductive layer on the nitride epitaxial layer so as to form the back electrode on the nitride epitaxial layer.

18. The manufacturing method according to any one of claims 12 to 16, wherein the step S5 specifically includes:

s51, preparing a front electrode on one side of the nitride epitaxial layer, which is far away from the back electrode, after the separation;

S52, respectively determining a plurality of dividing positions on the nitride epitaxial layer with the front electrode, and respectively dividing the nitride epitaxial layer into a plurality of sub-units along each dividing position;

s53, respectively preparing an anti-reflection layer on each subunit;

S54, respectively forming through holes on the lower surface of the supporting substrate of each subunit, wherein each through hole respectively penetrates through the supporting substrate to be in contact with the back electrode or penetrate into the back electrode;

and S55, dividing the supporting substrate and the back electrode along each dividing position respectively to obtain a plurality of batteries.

Technical Field

The invention relates to the technical field of photovoltaic cells and manufacturing, in particular to a flexible nitride thin-film solar cell and a manufacturing method thereof.

Background

In recent years, on the one hand, nitride semiconductor materials represented by indium gallium nitride (In _x Ga _1-x N,0 ≦ x ≦ 1) and indium aluminum nitride (In _y Al _1-y N,0 ≦ y ≦ 1) have been widely used In the manufacture of solar cells because their forbidden bandwidths are almost perfectly matched with the solar spectrum or completely cover the energy range of solar spectrum radiation.

disclosure of Invention

Technical problem to be solved

The invention provides a flexible nitride thin-film solar cell and a manufacturing method thereof, wherein the solar cell has the advantages of high absorption coefficient, high energy conversion rate, high temperature resistance and radiation resistance, and simultaneously, a back electrode of the solar cell can realize the function of electrode conduction and can be used as a prestress strengthening layer during cell manufacturing, and the prestress strengthening layer does not need to be additionally removed after the cell manufacturing is finished.

(II) technical scheme

in order to solve the technical problem, the invention provides a flexible nitride film solar cell which comprises a support substrate, a back electrode, a nitride epitaxial layer and a front electrode which are sequentially arranged from bottom to top, wherein the back electrode comprises a first pre-stress layer.

preferably, a dielectric reflection layer is arranged between the nitride epitaxial layer and the back electrode, and the dielectric reflection layer comprises a plurality of reflection blocks, and each reflection block is discretely distributed between the nitride epitaxial layer and the back electrode.

preferably, an antireflection layer is disposed on the front electrode.

preferably, the back electrode comprises an adhesion layer, the first pre-stress layer and a conductive layer which are sequentially connected, the adhesion layer is connected with the nitride epitaxial layer, and the conductive layer is connected with the support substrate.

Preferably, an electrode reflecting layer is arranged between the adhesion layer and the first pre-stress layer;

preferably, the adhesion layer has at least one metal element of Ni, Pd, Mo, Pt, Cr, Ti, Ta, and W;

And/or the electrode reflection layer has at least one metal element of Ag and Al;

And/or the first pre-stress layer is provided with at least one metal element of Ni, Mo, Cr, Pd, Pt, W, Ti and Ta;

and/or the conductive layer has at least one metal element of Al, Cu, Ni, Ag, Au, and Pt.

Preferably, a barrier layer is arranged between the first pre-stress layer and the conductive layer.

preferably, the barrier layer has at least one metal element of W, Mo, Ta, and Ti;

Preferably, the nitride epitaxial layer includes a buffer layer, an n-type doping layer, an undoped multiple quantum well layer, and a p-type doping layer, which are sequentially connected, the buffer layer is connected to the front electrode, and the p-type doping layer is connected to the back electrode.

preferably, the undoped multi-quantum well layer comprises 1-200 pairs of periodic structures formed by In _xw Ga _yw Al _1-xw-yw N/In _xb Ga _yb Al _1-xb-yb N, each period of each periodic structure consists of a quantum well layer In _xw Ga _yw Al _1-xw-yw N and a quantum barrier layer In _xb Ga _yb Al _1-xb-yb N, wherein xw is more than or equal to 0 and less than or equal to 1, yw is more than or equal to 0 and less than or equal to 1, xb is more than or equal to 0 and less than or equal to 1, yb is more than or equal to 0 and less than or equal to 1, xw + yw is more than or equal to 0 and less than or equal to 1, and xb is more than or equal to 0 and less than or equal.

Preferably, the supporting substrate includes a metal substrate or a polymer substrate, and when the supporting substrate is the polymer substrate, a through hole is formed in the supporting substrate, and the through hole penetrates through the polymer substrate to communicate with the back electrode or penetrate into the back electrode.

The invention also provides a manufacturing method of the flexible nitride thin film solar cell, which comprises the following steps:

s1, preparing a sacrificial layer on the upper surface of the substrate wafer;

S2, preparing a nitride epitaxial layer on the upper surface of the sacrificial layer;

S3, preparing a back electrode on the upper surface of the nitride epitaxial layer, wherein a first pre-stress layer is arranged in the back electrode;

S4, fixing a support substrate on the upper surface of the back electrode;

and S5, separating the nitride epitaxial layer from the sacrificial layer, and sequentially preparing a front electrode and an anti-reflection layer on the separated nitride epitaxial layer.

Preferably, between step S3 and step S4, or between step S4 and step S5, the method further includes:

s31, preparing a second pre-stress layer on the lower surface of the substrate wafer, wherein the first pre-stress layer and the second pre-stress layer respectively apply a pair of balanced tensile stresses which are opposite to each other to the nitride epitaxial layer.

Preferably, the second pre-stress layer includes at least one metal element of Cr, Mo, Ni, Pd, Pt, Ti, and Ta.

Preferably, the step S2 specifically includes:

Preparing a dielectric reflection layer on the upper surface of the nitride epitaxial layer, wherein the dielectric reflection layer comprises a plurality of reflection blocks, and each reflection block is discretely distributed between the nitride epitaxial layer and the back electrode.

Preferably, the separating in step S5 further includes, before the removing, removing the edge of the nitride epitaxial layer by an etching process to form a step structure between the edge of the nitride epitaxial layer and the sacrificial layer.

Preferably, the step S3 specifically includes:

And sequentially preparing an adhesion layer, an electrode reflection layer, the first pre-stress layer, a barrier layer and a conducting layer on the nitride epitaxial layer so as to form the back electrode on the nitride epitaxial layer.

preferably, the step S5 specifically includes:

S51, preparing a front electrode on the side, away from the back electrode, of the nitride epitaxial layer after the separation;

s52, respectively determining a plurality of dividing positions on the nitride epitaxial layer with the front electrode, and respectively dividing the nitride epitaxial layer into a plurality of sub-units along each dividing position;

S53, respectively preparing an anti-reflection layer on each subunit;

S54, respectively forming through holes on the lower surface of the supporting substrate of each subunit, wherein each through hole respectively penetrates through the supporting substrate to be in contact with the back electrode or penetrate into the back electrode;

And S55, dividing the supporting substrate and the back electrode along each dividing position respectively to obtain a plurality of batteries.

(III) advantageous effects

the technical scheme of the invention has the following beneficial effects:

Firstly, in the flexible nitride thin-film solar cell, the cell unit comprises a supporting substrate, a back electrode, a nitride epitaxial layer and a front electrode which are sequentially arranged from bottom to top, the back electrode comprises a first pre-stress layer, and the solar cell not only has the advantages of high absorption coefficient, high energy conversion efficiency, high temperature resistance, radiation resistance and the like, but also has the advantages of light weight, bending and stretching, and the technical advantages greatly promote the application field of the flexible solar cell.

Meanwhile, in the manufacturing method of the flexible nitride thin-film solar cell, the sacrificial layer is additionally arranged between the substrate wafer and the nitride epitaxial layer, the graphene sacrificial layer and the nitride epitaxial layer can form a molecular bond with weaker bond energy at the interface connection position, and the chemical bond strength of the graphene sacrificial layer is far smaller than that of a covalent bond, so that a powerful condition is provided for mechanical stripping of the nitride epitaxial layer.

Particularly, in the flexible nitride thin-film solar cell, the back electrode can have the functions of ohmic contact and electrode conduction realization, can be used as a prestress strengthening layer during cell manufacturing, provides enough stress support for stripping of the nitride epitaxial layer, does not need to be additionally cleaned after the cell is manufactured, optimizes the production process flow and simultaneously provides reliable guarantee for the structure strengthening of the cell.

The manufacturing method of the invention discloses a double-sided stress structure, which can solve the problem that a residual stress management layer needs to be additionally removed when a nitride epitaxial layer is separated from a substrate wafer, and can also reduce the curvature of the wafer, ensure that the manufactured solar cell has good smoothness and improve the yield of mechanical stripping.

Specifically, the invention ensures the direct contact between the back electrode and the nitride epitaxial layer through the discrete arrangement structure of the dielectric reflection layer, thereby realizing multiple functions of the back electrode, specifically comprising the following steps: on one hand, the back electrode has ohmic contact and electric conduction functions; in the second aspect, the back electrode is used as a first pre-stress layer to apply pre-stress to the nitride epitaxial layer, so that not only can enough stripping stress be provided for the nitride epitaxial layer during stripping, but also reliable support can be provided for the manufactured battery structure; in the third aspect, when the nitride epitaxial layer is stripped, the back electrode is used as a first pre-stress layer to act synchronously with a second pre-stress layer on the substrate wafer, so that the magnitude of the pre-stress action is effectively increased, the stress action of the nitride epitaxial layer near the position of the graphene sacrificial layer is increased, the curvature of the wafer is reduced, and the stripping flatness of the nitride epitaxial layer is improved; in the fourth aspect, in the whole manufacturing method, a separate removing procedure of the stress management layer is not required to be introduced, so that the process flow is effectively simplified, and the manufacturing efficiency is improved.

Drawings

Fig. 1 is a schematic structural diagram of a flexible nitride thin film solar cell according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a back electrode according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an epitaxial layer according to an embodiment of the present invention;

fig. 4 to 16 are schematic sectional views of the flexible nitride thin film solar cell in sequence at various stages of the method for manufacturing the flexible nitride thin film solar cell according to the embodiment of the invention;

Wherein the content of the first and second substances,

fig. 9a and 9b are graphs comparing stress states of the battery before and after the pre-stress layer is prepared in the method according to the embodiment of the present invention.

in each of the above figures, 100, an anti-reflection layer; 200. a front electrode; 310. a substrate wafer; 320. a sacrificial layer; 330. a nitride epitaxial layer; 331. a buffer layer; 332. an n-type doped layer; 333. a non-doped multi-quantum well layer; 334. a p-type doped layer; 400. a dielectric reflective layer; 500. a back electrode; 510. a through hole; 520. an adhesive layer; 530. an electrode reflective layer; 540. a first pre-stressed layer; 550. a barrier layer; 560. a conductive layer; 600. a support substrate; 700: and a second pre-stressed layer.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

In the description of the present invention, "a plurality" means two or more unless otherwise specified. The terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships that are based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

the embodiment discloses a flexible nitride thin-film solar cell, which not only has the advantages of high absorption coefficient, high energy conversion efficiency, high temperature resistance, radiation resistance and the like, but also has the advantages of light weight, flexibility and extensibility, and the technical advantages can greatly contribute to the application field of the flexible solar cell.

Specifically, as shown in fig. 1 and fig. 2, the solar cell includes a supporting substrate 600, a back electrode 500, a nitride epitaxial layer 330 and a front electrode 200, which are sequentially arranged from bottom to top, where the back electrode 500 includes a first pre-stress layer 540, the back electrode 500 can achieve an electrode conduction effect, and the first pre-stress layer 540 of the back electrode 500 can be used as a stress supporting layer in a cell structure, so as to advantageously strengthen the strength of the cell structure, and can also be used as a pre-stress strengthening layer in cell manufacturing, so as to provide sufficient stress support for the peeling of the nitride epitaxial layer 330, so as to ensure that the nitride epitaxial layer 330 can be quickly and efficiently peeled from a substrate wafer when the cell is manufactured, and the peeled nitride epitaxial layer 330 has a complete structure, so as to ensure the quality of the cell, and after the cell is manufactured, the pre-stress strengthening layer (i.e. the first pre-stress layer 540) does not, the production process flow is optimized, and meanwhile, reliable guarantee is provided for the structural reinforcement of the battery.

the anti-reflection layer 100 is preferably disposed on the front electrode 200to obtain a better photoelectric conversion efficiency; preferably, a dielectric reflection layer 400 is arranged between the nitride epitaxial layer 330 and the back electrode 500, the dielectric reflection layer 400 comprises a plurality of reflection blocks, each reflection block is discretely distributed between the nitride epitaxial layer 330 and the back electrode 500, and the dielectric reflection layer 400 is in a discrete point array structure and is uniformly distributed on the nitride epitaxial layer 330; meanwhile, in the area not covered by the dielectric reflective layer 400, the back electrode 500 can be in direct and effective contact with the nitride epitaxial layer 330, i.e., the back electrode 500 is simultaneously formed on the dielectric reflective layer 400 and the epitaxial layer 330.

the back electrode 500 of the present embodiment is an ohmic contact electrode formed by a plurality of metal thin film functional layers, and has a large pre-stress. Specifically, as shown in fig. 2, the back electrode 500 includes an adhesion layer 520, a first pre-stress layer 540, and a conductive layer 560, which are sequentially connected in a direction from the nitride epitaxial layer 330 toward the support substrate, the adhesion layer 520 being connected to the nitride epitaxial layer 330, and the conductive layer 560 being connected to the support substrate 600. Since the first pre-stress layer 540 is disposed inside the back electrode 500, the entire structure of the back electrode 500 can be regarded as the first pre-stress layer 540.

Preferably, the thickness of the first prestress layer is 10-100000 nm; the adhesion layer 520 has at least one metal element of Ni, Pd, Mo, Pt, Cr, Ti, Ta, and W; and/or the first pre-stress layer 540 has at least one metal element of Ni, Mo, Cr, Pd, Pt, W, Ti, and Ta; and/or the conductive layer 560 has at least one metal element of Al, Cu, Ni, Ag, Au, and Pt. Preferably, the electrode reflection layer 530 is disposed between the adhesion layer and the first pre-stress layer, so as to enhance back reflection of the thin film battery, thereby improving photoelectric conversion efficiency of the device, and further preferably, the electrode reflection layer 530 has at least one metal element of Ag and Al. It is preferable that a barrier layer 550 is disposed between the first pre-stress layer 540 and the conductive layer 560 to prevent atomic diffusion between the first pre-stress layer 540 and the conductive layer 560 from occurring, thereby adversely affecting the conductive properties, and it is further preferable that the barrier layer 550 has at least one metal element of W, Mo, Ta, and Ti.

as shown in fig. 3, the nitride epitaxial layer 330 of the present embodiment includes a plurality of nitride thin film sublayers, and particularly, the nitride epitaxial layer 330 includes a buffer layer 331, an n-type doping layer 332, an undoped mqw layer 333, and a p-type doping layer 334 which are sequentially connected in a direction from the front electrode 200 toward the back electrode 500, and the buffer layer 331 is connected to the front electrode 200 and the p-type doping layer 334 is connected to the back electrode 500. Preferably, the thickness of the buffer layer 331 is 0.001 to 10 μm; the thickness of the n-type doped layer 332 is 0.1-20 μm; the thickness of the non-doped multi-quantum well layer 333 is 1-5000 nm; the thickness of the p-type doped layer 334 is 0.05 to 5 μm.

Furthermore, the buffer layer 331 is composed of at least one nitride Al _x1 In _x1 Ga _x1 N, wherein 0 is equal to or less than x _x1 and equal to or less than 1, 0 is equal to or less than y _x1 and equal to or less than 1, x _x1 + y _x1 is equal to or less than 1, the N-type doped layer 332 is composed of at least one nitride Al _x1 In _x1 Ga _x1 N, wherein 0 is equal to or less than x _x1 and equal to or less than 1, 0 is equal to or less than y _x1 and equal to or less than 1, x _x1 + y _x1 is equal to or less than 1, and the N-type doped layer 332 is doped with at least one element selected from Si, Sn, S, Se and Te, the undoped multi-quantum well layer 333 comprises 1-200 pairs of periodic structures composed of In _x1 Ga _x1 Al _x1 N/In _x1 Ga _x1 Al _x1 N, each periodic structure is composed of quantum _x1 Cd _x1 N and quantum _x1 N, wherein 0 is equal to or less than 0, 0 is equal to or less than 0, x _x1 is equal to or less than 1, and equal to or less than 0, wherein the N + x _x1 is composed of one element doped In _x1, and equal to or less than 0.

In the present embodiment, the thickness of the front electrode 200 is preferably 0.01 to 10 μm, and the front electrode 200 preferably includes at least one metal element selected from Ti, Au, Al, Cr, Ni, Pt, Ag, W, and Pb.

In the battery according to this embodiment, the supporting substrate 600 preferably includes a metal substrate or a polymer substrate. When the supporting substrate 600 is a metal substrate, the supporting substrate 600 can be directly used as a conductive carrier, so that the back electrode 500 is directly conductive with the outside through the supporting substrate 600to realize an electrode function; when the supporting substrate 600 is a polymer substrate, a through hole 510 is formed in the supporting substrate 600, and the through hole 510 penetrates through the polymer substrate (i.e., the supporting substrate 600) to communicate with the back electrode 500 or penetrate into the back electrode 500, so that a wire is introduced through the through hole 510 to make the back electrode 500 electrically conductive with the outside, thereby achieving electrical connection.

As shown in fig. 4 to 16, the present embodiment also provides a method for manufacturing a flexible nitride thin film solar cell, which is used for manufacturing the flexible nitride thin film solar cell as described above. Specifically, the method comprises the following steps:

S1, preparing a sacrificial layer 320 on the upper surface of the substrate wafer 310;

s2, preparing a nitride epitaxial layer 330 on the upper surface of the sacrificial layer 320;

S3, preparing a back electrode 500 on the upper surface of the nitride epitaxial layer 330, wherein a first pre-stress layer 540 is disposed in the back electrode 500;

S4, fixing the supporting substrate 600 on the upper surface of the back electrode 500;

s5, separating the nitride epitaxial layer 330 from the sacrificial layer 320, and sequentially preparing the front electrode 200 and the anti-reflection layer 100 on the separated nitride epitaxial layer 330.

in this embodiment, in order to facilitate safe peeling of the nitride epitaxial layer 330 from the substrate wafer 310 during preparation, it is preferable to prepare the sacrificial layer 320 on the substrate wafer 310, before the nitride epitaxial layer 330 is separated from the substrate wafer 310, the nitride epitaxial layer 330 is connected to the substrate wafer 310 through the sacrificial layer 320, and the additional sacrificial layer 320 is preferably a graphene layer, and the graphene layer and the nitride epitaxial layer 330 can form a molecular bond with weak bond energy at the interface connection position, and the chemical bond strength is much less than that of a covalent bond, thereby providing a strong condition for peeling of the nitride epitaxial layer 330.

in step S1, the method specifically includes: sacrificial layer 320 is prepared on substrate wafer 310 using a hydrocarbon chemical vapor deposition process or a graphitization annealing process.

The chemical vapor deposition method of the hydrocarbon comprises the following specific steps: firstly, placing a SiC substrate wafer 310 into a chemical vapor deposition reaction furnace with the temperature of 1300-1800 ℃ and the pressure of more than or equal to 1mTorr, then introducing hydrogen into the reaction furnace, and annealing and cleaning the substrate wafer 310 at the temperature of 1300-1800 ℃; then, introducing hydrocarbon and keeping the dynamic introduction of argon; and finally, introducing hydrogen, and annealing at the temperature of 600-1800 ℃ to obtain the substrate wafer 310 with the graphene sacrificial layer 320.

The graphitization annealing treatment method comprises the specific steps of firstly, placing the SiC substrate wafer 310 into a hydrogen atmosphere with the temperature of 1200-1450 ℃ to carry out high-temperature annealing and cleaning, then, adjusting the process conditions to be a vacuum environment with the temperature of 1500-2000 ℃ and the pressure of less than or equal to 10 ^-3 Pa or an argon atmosphere with the temperature of 1300-1800 ℃ and the pressure of more than or equal to 10 ² Pa, thereby realizing the graphitization process through sublimation of Si atoms on the surface of the substrate wafer 310, and finally, carrying out annealing treatment in the hydrogen atmosphere to obtain the substrate wafer 310 with the graphene sacrificial layer 320.

In step S2, the method specifically includes: sequentially preparing a buffer layer 331, an n-type doping layer 332, an undoped multi-quantum well layer 333, and a p-type doping layer 334 on the sacrificial layer 320 to prepare a nitride epitaxial layer 330; preferably, the nitride epitaxial layer 330 is prepared by at least one of metal organic chemical vapor deposition, molecular beam epitaxy, radio frequency magnetron sputtering, pulsed laser deposition, and remote plasma enhanced chemical vapor deposition, and the growth temperature of the nitride epitaxial layer 330 during preparation is in the range of 200 ℃ to 1500 ℃; the dielectric reflective layer 400 is preferably formed on the upper surface of the nitride epitaxial layer 330, and further, the dielectric reflective layer 400 is preferably formed on the nitride epitaxial layer 330 by at least one of photolithography, screen printing, and ink-jet printing, so that the respective reflective lumps of the dielectric reflective layer 400 are discretely and uniformly distributed between the nitride epitaxial layer 330 and the back electrode 500.

in step S3, the method specifically includes: the adhesion layer 520, the electrode reflection layer 530, the first pre-stress layer 540, the barrier layer 550 and the conductive layer 560 are sequentially prepared on the nitride epitaxial layer 330 by at least one of electroplating and a physical vapor deposition method to form the back electrode 500 on the nitride epitaxial layer 330.

In step S5, the separation may be mechanical peeling. Before the separation in step S5, the method further includes: the edge of the nitride epitaxial layer 330 is removed through an etching process to form a stepped structure between the edge of the nitride epitaxial layer 330 and the sacrificial layer 320.

In step S5, the method specifically includes:

S51, preparing the front electrode 200 on the side of the nitride epitaxial layer 330 away from the back electrode 500 after the separation;

s52, determining a plurality of dividing positions on the nitride epitaxial layer 330 with the front electrode 200, and dividing the nitride epitaxial layer 330 into a plurality of sub-units along each dividing position;

s53, respectively preparing an anti-reflection layer 100 on each subunit;

S54, respectively forming through holes 510 on the lower surface of the supporting substrate 600 of each sub-unit, wherein each through hole 510 respectively penetrates through the supporting substrate 600to contact the back electrode 500 or penetrate into the back electrode 500.

s55, the supporting substrate 600 and the back electrode 500 are divided along the respective dividing positions, respectively, to obtain a plurality of cells.

Specifically, in step S54, the method specifically includes: the through holes 510 are formed by at least one of mechanical perforation, plasma etching perforation and laser perforation, and the arrangement of the through holes 510 can provide basic positioning for division in the preparation process of the solar cell, thereby improving the preparation efficiency.

In the present embodiment, between step S3 and step S4, or between step S4 and step S5, the method further includes:

S31, preparing a second pre-stress layer 700 on the lower surface of the substrate wafer 310, and applying a pair of balanced tensile stresses opposite to each other to the nitride epitaxial layer 330 by the first pre-stress layer 540 and the second pre-stress layer 700, thereby forming a double-sided stress structure.

in step S31, the method specifically includes: the second pre-stress layer 700 is prepared by at least one of electroplating and physical vapor deposition, wherein the second pre-stress layer 700 includes at least one metal element of Cr, Mo, Ni, Pd, Pt, Ti, and Ta.

in the present embodiment, the back electrode 500 includes the first pre-stress layer 540, and the second pre-stress layer 700 is formed on the substrate wafer 310, and the thickness of the second pre-stress layer is preferably 1-5000 μm. The back electrode 500 can thus function as an electrode in the fabricated battery; meanwhile, in the process of manufacturing the battery, the first pre-stress layer 540 and the second pre-stress layer 700 are respectively prepared on the upper side and the lower side of the nitride epitaxial layer 330, so that a pair of balanced tensile stresses which are opposite to each other is respectively applied to the nitride epitaxial layer 330, and a double-sided stress structure is formed on the two sides of the nitride epitaxial layer 330; to effectively improve the pre-stress effect, a metal film is formed on the bottom of the substrate wafer 310 of this embodiment, so as to form the second pre-stress layer 700. The double-sided stress structure enables the nitride epitaxial layer 330 to be kept in a horizontal state when being separated from the substrate wafer 310, so that the problem that the residual stress management layer needs to be additionally removed when the nitride epitaxial layer 330 is separated from the substrate wafer 310 can be solved, the curvature of the wafer can be reduced, the manufactured solar cell is guaranteed to have good smoothness, and the yield of mechanical stripping is improved.

as shown by comparing fig. 9a and fig. 9b, it can be seen that if only the first pre-stress layer 540 is provided, when the solar cell is fabricated, the nitride epitaxial layer 330 is excessively bent to one side under the pre-stress of one side, so as to affect the overall flatness of the wafer, and in the embodiment, the first pre-stress layer 540 and the second pre-stress layer 700 are used together to apply a pair of balance forces to the nitride epitaxial layer 330, so that the wafer bending is reduced, i.e., the wafer flatness is improved, under the condition of ensuring sufficient stress, so that the yield of the nitride epitaxial layer 330 during mechanical stripping can be improved.

in summary, the double-sided stress structure provides the back electrode 500 with ohm contact and conduction functions; on the other hand, the back electrode 500 serves as a first pre-stress layer 540 to apply pre-stress to the nitride epitaxial layer 330, so that the pre-stress acts synchronously with the second pre-stress layer 700 on the substrate wafer 310, the pre-stress action is effectively increased, the stress action of the nitride epitaxial layer 330 near the position of the graphene sacrificial layer 320 is increased, the curvature of the wafer is reduced, and the peeling flatness of the nitride epitaxial layer 330 is improved. In addition, in the whole manufacturing method, a separate removing procedure of the stress management layer is not required to be introduced, so that the process flow is effectively simplified, and the manufacturing efficiency is improved.

the solar cell and the manufacturing method are described in detail below with three specific embodiments.