CN211789038U - Passivation contact solar cell - Google Patents
Passivation contact solar cell Download PDFInfo
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- CN211789038U CN211789038U CN202020669926.0U CN202020669926U CN211789038U CN 211789038 U CN211789038 U CN 211789038U CN 202020669926 U CN202020669926 U CN 202020669926U CN 211789038 U CN211789038 U CN 211789038U
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Abstract
The utility model relates to a passivation contact solar cell, which comprises a silicon substrate, wherein the front surface of the silicon substrate sequentially comprises a tunneling layer, a heavily doped layer, a covering layer and an H-shaped grid line arranged on the covering layer from inside to outside, and the H-shaped grid line comprises a main grid line and an auxiliary grid line which are vertical to each other; the back surface of the silicon substrate sequentially comprises a tunneling layer, a heavily doped layer and a covering layer from inside to outside; two sides of the secondary grid line are provided with groove structures; wherein the groove structure extends longitudinally to the interior of the silicon substrate. The utility model discloses a set up groove structure in vice grid line both sides, block other interference lines except normal current transmission line, consequently, adopt the utility model provides a passivation contact solar cell can show the accuracy that improves test passivation contact structure's contact resistivity.
Description
Technical Field
The utility model relates to a solar cell technical field, concretely relates to passivation contact solar cell.
Background
The passivation contact structure, such as a tunneling oxide layer/a doped polycrystalline silicon layer, an ultrathin intrinsic amorphous silicon layer/a heavily doped amorphous silicon layer, has excellent interface passivation performance, can obviously reduce metal contact recombination, has excellent contact performance, and promotes effective transmission of majority carriers. The excellent performance of the passivation contact structure is widely concerned by research institutions and enterprises, wherein the research institutions such as Fraunhofer and ISFH solar energy system research institute in germany respectively develop TOPCon batteries and POLO batteries aiming at tunneling oxide layer/doped polysilicon layer structures, and the enterprises such as the china and the city convert the small-sized passivation contact battery technology in laboratories into large-area full-sized mass production technology. For the large-area full-size mass production technology, a method which is simple, quick and capable of accurately measuring the contact resistivity of the passivation contact structure is developed, and the method has important significance for optimizing the contact performance of the passivation contact structure.
There are two common methods for testing contact resistivity: the line transmission method (TLM) and the Core Scan method. The Core Scan method has the following disadvantages that the Core Scan method cannot be widely used in enterprises: 1) the accurate contact resistivity cannot be obtained, and only the maximum possible value of the contact resistivity can be given; 2) irreparable damage is caused to the sample, so that the same battery cannot be tested and compared repeatedly; 3) the equipment price is expensive, and the use cost is high. For a sample with only a single conductive thin layer, the TLM method can accurately test the contact resistivity, and has the advantages of simple sample preparation, repeatable test and the like, so that the TLM method is widely applied to cells without passivation contact structures, such as Al-BSF, PERC, PERT and the like, by photovoltaic enterprises.
For samples without passivation contact structures, such as the front surface of a p-PERC cell, the TLM method is used for testing the contact resistivity, the current is limited to be transmitted in a phosphorus-doped emitter, only a single transmission path is needed, and the contact resistivity of the emitter and metal is measured. The passivation contact structure on the silicon substrate has a plurality of conductive thin layers, such as crystalline silicon/tunnel oxide/doped polysilicon (c-Si/SiOx/Poly-Si), and the contact resistivity current has a plurality of transmission paths by using a conventional TLM method: 1. electrode → heavily doped Poly-Si → electrode; 2. electrode → heavily doped Poly-Si → SiOx → c-Si → SiOx → heavily doped Poly-Si → electrode; in actual battery operation, carriers in c-Si need to tunnel through the SiOx layer to enter the heavily doped Poly-Si layer and then be collected by the metal electrode, so that a path 2 is consistent with a carrier transmission path in battery operation, and a path 1 is an interference path; the current transmission path is increased if the TCO layer is present on the heavily doped polysilicon layer. The presence of multiple transmission paths can make it difficult to accurately determine the contact resistivity of a passivated contact structure using conventional TLM methods.
In order to solve the problem that the passivation contact structure is not accurately tested by the conventional TLM method, the Germany ISFH research institute adopts a photoetching mask and wet etching process to remove SiOx/Poly-Si between the metal electrodes and eliminate the transmission path 1, and the Germany Fraunhofer adopts Reactive Ion Etching (RIE) to remove the SiOx/Poly-Si between the metal electrodes, so that the same effect is achieved. Although the two methods can eliminate the interference of redundant transmission paths and accurately test the contact resistivity, the photoetching mask process and the RIE process have the defects of complex process, high cost, long time consumption and difficulty in mass production of samples, and are difficult to apply in enterprises.
In view of the above, it is desirable to provide a passivated contact solar cell for improving the accuracy of testing the contact resistivity of the passivated contact structure.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome prior art not enough, provide a passivation contact solar cell.
The utility model relates to a passivation contact solar cell, which comprises a silicon substrate,
the front surface of the silicon substrate sequentially comprises a tunneling layer, a heavily doped layer, a covering layer and an H-shaped grid line arranged on the covering layer from inside to outside, wherein the H-shaped grid line comprises a main grid line and an auxiliary grid line which are perpendicular to each other;
the back surface of the silicon substrate sequentially comprises a tunneling layer, a heavily doped layer and a covering layer from inside to outside;
two sides of the secondary grid line are provided with groove structures; wherein the groove structure extends longitudinally to the interior of the silicon substrate.
The utility model provides a pair of passivation contact solar cell still includes following subsidiary technical scheme:
and the distance between the groove structure and the adjacent secondary grid line is 40-80 μm.
Wherein the width of the groove structure is 60-120 mu m.
Wherein the thickness of the tunneling layer is 0.5-5.0 nm;
wherein the thickness of the covering layer is 60-90 nm.
Wherein the silicon substrate has a resistivity of 0.3 to 10 Ω · cm and a thickness of 90 to 300 μm.
The spacing between adjacent secondary grid lines is 1200-1800 mu m, the width of the secondary grid lines is 40-80 mu m, and the height of the secondary grid lines is 10-30 mu m.
The utility model discloses an implement including following technological effect:
the utility model discloses creatively sets up groove structure in vice grid line both sides, blocks other interference lines except normal current transmission line, consequently, adopts the utility model provides a passivation contact solar cell can show the accuracy that improves test passivation contact structure's contact resistivity.
Drawings
Fig. 1 is a schematic structural view of a passivated contact solar cell of the present invention;
in the figure, 1-crystalline silicon substrate, 2-tunneling layer, 3-heavily doped layer, 4-covering layer, 5-secondary grid line and 7-groove structure.
Detailed Description
The present invention will be described in detail with reference to examples.
The specific embodiments are only for explaining the present invention, and not for limiting the present invention, and those skilled in the art can make modifications without inventive contribution to the present embodiments as needed after reading the present specification, but all of them are protected within the scope of the claims of the present invention.
The utility model discloses a passivation contact solar cell, as shown in figure 1, comprising a silicon substrate 1;
the front surface of the silicon substrate 1 sequentially comprises a tunneling layer 2, a heavily doped layer 3, a covering layer 4 and an H-shaped grid line arranged on the covering layer from inside to outside, wherein the H-shaped grid line comprises a main grid line and an auxiliary grid line 5 which are perpendicular to each other;
the back surface of the silicon substrate sequentially comprises a tunneling layer 2, a heavily doped layer 3 and a covering layer 4 from inside to outside;
The utility model discloses creatively sets up groove structure in vice grid line both sides, blocks other interference lines except normal current transmission line, consequently, adopts the utility model provides a passivation contact solar cell can show the accuracy that improves test passivation contact structure's contact resistivity.
In one embodiment, the distance between the groove structure 7 and the adjacent secondary grid line 5 is 40-80 μm.
In one embodiment, the width of the groove structure 7 is 60-120 μm.
In one embodiment, the tunneling layer 2 has a thickness of 0.5-5.0 nm;
in one embodiment, the thickness of the covering layer 4 is 60 to 90 nm.
In one embodiment, the silicon substrate 1 has a resistivity of 0.3 to 10 Ω · cm and a thickness of 90 to 300 μm.
In one embodiment, the spacing between adjacent secondary grid lines 5 is 1200 to 1800 μm, the width of the secondary grid lines 5 is 40 to 80 μm, and the height of the secondary grid lines 5 is 10 to 30 μm.
The utility model discloses a passivation contact solar cell, its method of testing contact resistivity includes following step:
(1) carrying out slotting treatment on the passivation contact structures next to the two sides of the auxiliary grid line along the direction parallel to the auxiliary grid line on the battery piece to form a groove structure; wherein the groove structure longitudinally extends to the inner part of the silicon substrate;
(2) cutting the region containing the groove structure on the battery piece along the direction parallel to the main grid line on the battery piece to obtain a test sample; wherein the test sample does not contain a bus bar;
(3) testing the corresponding resistance value between the auxiliary grid lines on the test sample;
exemplarily, assuming that the distance between two adjacent sub-gate lines (1 st and 2 nd) is d, the total resistance value of the corresponding test is RT1If the distance between the 1 st and 3 rd sub-grid lines is 2d, the resistance value of the corresponding test is RT2The distance between the 1 st and the n +1 th sub-grid lines is nd, and the resistance value of the corresponding test is RTn。
(4) Drawing a scatter diagram by taking the distance between the auxiliary grid lines as an abscissa and the resistance value corresponding to the distance between the auxiliary grid lines as an ordinate, and performing linear fitting to obtain the slope and intercept of a linear function; and calculating the contact resistivity according to the slope and the intercept of the linear function and a line transmission model.
The utility model provides a pair of passivation contact solar cell still includes following subsidiary technical scheme:
in one embodiment, in the step (4), a scatter diagram is drawn by taking different inter-grid line distances as abscissa and resistance values corresponding to the different inter-grid line distances as ordinate, and linear fitting is performed to obtain a slope and an intercept of a linear function.
Illustratively, the abscissa is d, 2d … … nd, and the ordinate is RT1，RT2……RTn(ii) a And drawing a scatter diagram for linear fitting, and calculating the contact resistivity by using a line transmission model.
In one embodiment, in the step (1), the distance between the groove structure and the adjacent secondary grid line is 40-80 μm.
In one embodiment, in the step (1), the width of the groove structure is 60-120 μm.
In one embodiment, in the step (2), the width of the test sample is 1.0-3.0 cm, and the test sample comprises at least 5 mutually parallel secondary grid lines.
In one embodiment, in step (4),
the calculation formula of the linear transmission model is as follows:
in one embodiment, RTD is the spacing of the sub-grid lines, RSIs the sheet resistance of the silicon substrate, W is the width of the sample to be measured, LTIs the transmission length;
by linear fitting, a linear function is obtained as:
RT＝kd+b (2)
in one embodiment, k is the slope of the linear function, b is the intercept of the linear function;
the following is obtained by formula (1) and formula (2):
RS＝kW
contact resistivity ρcThe calculation formula of (2) is as follows:
in one embodiment, prior to step (1), the method further comprises:
(1) firstly, preparing a passivation contact structure on a silicon substrate, then depositing a covering layer on the surface of the passivation contact structure, and finally printing an H-shaped grid line on the covering layer, wherein the H-shaped grid line comprises a main grid line and an auxiliary grid line which are vertical to each other, and sintering or drying the H-shaped grid line.
In one embodiment, in step (1)', the passivation contact structure comprises, in order from the inside out, a tunneling layer and a heavily doped layer;
the tunneling layer is made of SiOXOr intrinsic amorphous silicon with a thickness of 0.5-5.0 nm;
the heavily doped layer is made of polysilicon or amorphous silicon, and the conductivity type of the heavily doped layer is consistent with that of the silicon substrate.
In one embodiment, in step (1)', the capping layer is SiNxOr a transparent conductive oxide layer having a thickness of 60 to 90 nm. Among them, ITO, AZO, FTO, etc. may be mentioned.
In one embodiment, in the step (1)', the silicon substrate has a conductivity type of N-type or P-type, a resistivity of 0.3 to 10 Ω & cm, and a thickness of 90 to 300 μm.
In one embodiment, in the step (1)', the spacing between adjacent grating lines is 1200 to 1800 μm, the width of the grating lines is 40 to 80 μm, and the height of the grating lines is 10 to 30 μm.
The following will explain the production method of the utility model in detail by specific examples.
(1) Firstly, removing a damaged layer of a full-size N-type monocrystalline silicon substrate 1 with the resistivity of 0.3-2.1 omega-cm, etching or polishing, placing the N-type monocrystalline silicon substrate 1 in low-pressure chemical vapor deposition equipment, growing a tunneling silicon oxide layer 2 with the thickness of 1.0-1.5 nm through thermal oxidation, and depositing an in-situ phosphorus-doped polycrystalline silicon layer 3 with the thickness of 100-400nm; annealing the passivated contact structure at high temperature, wherein the annealing temperature is 850-900 ℃, the annealing time is 15-60 min, and the peak doping concentration of phosphorus atoms in the annealed polycrystalline silicon layer is 1.0-4.0E +20cm-3. Then adopting PECVD to deposit a covering layer 4 on the tunneling oxide layer/the heavily doped polysilicon layer, wherein the covering layer is made of SiNXThe thickness is 75-85 nm. Finally, screen printing H-shaped grid lines on the covering layer, wherein the main grid and the auxiliary grid are vertical to each other, and sintering or drying treatment is carried out; the spacing between the secondary grid lines 5 is 1500 mu m, the width of the secondary grid lines 5 is 40-50 mu m, and the height of the secondary grid lines 5 is 16 mu m; the spacing of the main grid lines is 31.2mm, the width of the main grid lines is 700-800 mu m, and the height of the main grid lines is 12 mu m.
(2) Firstly, slotting the passivation contact structures next to two sides of the auxiliary grid line 5 by adopting picosecond laser along the direction parallel to the auxiliary grid line; the wavelength of the laser is 532nm, the frequency is 90-100 kHZ, the power percentage is 20-40%, and the scanning speed is 1500 mm/s; the groove structures 7 are located on two sides of the secondary grid line 5, the width of each groove structure is 60-120 mu m, the distance between each groove structure and the secondary grid line is 40-80 mu m, the depth of each groove structure 7 is 1.5-1.7 mu m, and the depth is larger than the sum of the thicknesses of the heavily doped layer and the covering layer, so that the groove structures 7 can longitudinally extend into the silicon substrate 1. Then taking out a strip-shaped sample along the direction parallel to the main grid, wherein the width of the sample is 1mm, a plurality of auxiliary grid lines 5 which are parallel to each other at equal intervals exist in the sample, and no main grid line is included; the long strip sample contains the number of mutually parallel finger lines 5 of not less than 5.
(3) Testing resistance values corresponding to different distances between the secondary grid lines on the test sample; assuming that the distance between two adjacent secondary grid lines (the 1 st and the 2 nd) is d, the total resistance value of the corresponding test is RT1If the distance between the 1 st and 3 rd sub-grid lines is 2d, the total resistance value of the corresponding test is RT2… …, the distance between the 1 st and the n +1 st sub-grid lines is nd, and the total resistance value of the corresponding test is RTn。
(4) Regard different grid line intervals as the abscissa, the different total resistance value that corresponds is as the ordinate, promptly: the abscissa is 1d and 2d … … nd, and the ordinate is RT1，RT2……RTn(ii) a Drawing a scatter plot forPerforming linear fitting;
the fitted function is:
RT＝kd+b (2)
wherein the abscissa is d, 2d … … nd, and the ordinate is RT1，RT2……RTnLinear fitting to obtain a slope k and an intercept b;
then, calculating the contact resistivity by using a line transmission model, wherein the formula of the line transmission model is as follows:
wherein R isTD is the spacing of the sub-grid lines, RSIs the sheet resistance of the silicon substrate, W is the width of the sample to be measured, LTIs the transmission length; wherein, the spacing d of the secondary grid lines in the implementation is 1.5, and the width of the test sample is 10 mm.
The following is obtained by formula (1) and formula (2):
RS＝kW
contact resistivity ρcThe calculation formula of (2) is as follows:
the linear fitting equation of the data acquired by the conventional TLM structure is RTThe contact resistivity was calculated to be 1.46m Ω · cm, 39.88 × d +0.482(ii) a The linear fitting equation of the data acquired by improving the TLM structure is RTThe contact resistivity was calculated to be 7.68m Ω · cm, 82.03 × d +1.592。
From the above data, it can be found that due to the existence of the heavily doped layer, a plurality of current transmission paths exist during the conventional TLM method test, and the measured total resistance values corresponding to different gate line pitches are relatively low, so that the measured contact resistivity value is seriously underestimated.
It should be finally noted that the above embodiments are only intended to illustrate the technical solutions of the present invention, and not to limit the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention can be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention.
Claims (7)
1. A passivated contact solar cell, characterized by: the solar cell comprises a silicon substrate, wherein the front surface of the silicon substrate sequentially comprises a tunneling layer, a heavily doped layer, a covering layer and an H-shaped grid line arranged on the covering layer from inside to outside, and the H-shaped grid line comprises a main grid line and an auxiliary grid line which are perpendicular to each other;
the back surface of the silicon substrate sequentially comprises a tunneling layer, a heavily doped layer and a covering layer from inside to outside;
two sides of the secondary grid line are provided with groove structures; wherein the groove structure extends longitudinally to the interior of the silicon substrate.
2. The solar cell of claim 1, wherein the groove structure is spaced from the adjacent minor grid line by 40-80 μm.
3. The solar cell of claim 1, wherein the groove structure has a width of 60-120 μm.
4. The solar cell according to any one of claims 1-3, wherein the tunneling layer has a thickness of 0.5-5.0 nm.
5. The solar cell according to any one of claims 1 to 3, wherein the thickness of the capping layer is 60 to 90 nm.
6. The solar cell according to any one of claims 1 to 3, wherein the silicon substrate has a resistivity of 0.3 to 10 Ω -cm and a thickness of 90 to 300 μm.
7. The solar cell according to any one of claims 1 to 3, wherein the pitch between adjacent minor grid lines is 1200 to 1800 μm, the width of the minor grid lines is 40 to 80 μm, and the height of the minor grid lines is 10 to 30 μm.
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| CN202020669926.0U CN211789038U (en) | 2020-04-27 | 2020-04-27 | Passivation contact solar cell |
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| CN202020669926.0U CN211789038U (en) | 2020-04-27 | 2020-04-27 | Passivation contact solar cell |
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