CN206148438U - Crystalline silicon solar cell based on siNiOx heterojunction - Google Patents

Abstract

The utility model provides a crystalline silicon solar cell based on siNiOx heterojunction, includes preceding electrode, niOx layer, crystalline silica absorbed layer, back of the body electric field, back electrode. Its structure begins to do in proper order from light facing surface: preceding electrode, niOx layer, crystalline silica absorbed layer, back of the body electric field, back electrode. This structure can effectively reduce the inside photocarrier's of solar battery complex, improves solar battery photoelectric conversion efficiency. This crystalline silica heterojunction battery can use has had crystalline silicon solar cell production facility preparation back of the body electric field, but its two -sidedly advances photo structure make full use of sunlight resource, increases the actual generated energy of photovoltaic module.

Description

A crystalline silicon solar cell based on Si/NiOx heterojunction

technical field

The utility model belongs to the field of solar cells, also belongs to the field of semiconductor devices, and relates to the structure of silicon solar cells.

Background technique

Silicon is abundant on the earth, and its optical band gap matches the solar spectrum, so it is one of the ideal materials for preparing solar cells. Since the purification technology of silicon materials and the preparation technology of silicon semiconductor devices are relatively mature, crystalline silicon solar cells account for most of the current total output of solar cells. However, with the advancement of technology, the photoelectric conversion efficiency of crystalline silicon solar cells based on homojunction structure has gradually approached the limit. The heterojunction solar cell can make full use of the difference in work function and energy band position between two different semiconductors, and can increase the open circuit voltage of the solar cell without reducing the short-circuit current, thereby improving the photoelectric conversion efficiency of the solar cell. Therefore, crystalline silicon solar cells based on heterojunctions are expected to further improve the photoelectric conversion efficiency in the future.

In order to improve the conversion efficiency of solar cells, the recombination of photogenerated carriers inside solar cells must be reduced as much as possible. In heterojunction solar cells, due to the difference in the lattice constants of the two semiconductor materials that constitute the heterojunction, defect states often exist at the heterojunction interface, resulting in a large number of recombination of photogenerated carriers at the heterojunction interface. Therefore, in the design of heterojunction solar cells, measures must be taken to suppress interfacial recombination.

In heterojunction solar cells, the use of selective contacts is considered to be one of the effective measures to reduce interfacial recombination. The so-called selective contact is to use the difference in the conduction band and valence band position between the semiconductor materials forming the heterojunction or the energy band bending inside the semiconductor to form a barrier to minority carriers at the heterojunction interface. Under the influence of the formed potential barrier, the transport of minority carriers to the selective contact is blocked but the transport of majority carriers is not affected. Thus, minority carriers are prevented from approaching the interface states, thereby inhibiting their recombination with majority carriers via surface defect states. At the same time, the barrier to minority carriers formed at the heterojunction interface can effectively reduce the dark current and increase the open circuit voltage. On the other hand, for majority carriers, the short-circuit current density does not decrease since their transport is not significantly affected.

Utility model content

The purpose of the utility model is to propose a crystalline silicon solar cell based on Si/ _NiOx heterojunction.

The utility model is achieved through the following technical solutions.

A crystalline silicon solar cell based on a Si/NiO _x heterojunction described in the utility model includes a front electrode, a NiO _x layer, a crystalline silicon absorption layer, a back electric field, and a back electrode. Its structure starts from the light-facing surface in order: front electrode, NiO _x layer, crystalline silicon absorption layer, back electric field, and back electrode.

The NiO _x layer is p-type doped.

The crystalline silicon absorbing layer is n-type or p-type doped.

The back electric field uses but is not limited to the following three forms: n-type doped layer plus silicon nitride passivation layer, or intrinsic amorphous silicon passivation layer plus n-type amorphous silicon heavily doped layer, or n-type Doped _TiOx layer.

The front electrode includes a transparent conductive layer and a metal grid electrode.

The back electrode includes a transparent conductive layer and a metal grid electrode, or only includes a metal grid electrode.

The utility model uses p-type doped NiO _x to form a heterojunction with crystalline silicon and applies it to solar cells. _NiOx is a transition metal oxide semiconductor with an optical bandgap of about 3eV. The electron affinity of NiO _x is small (about -2.1eV), so its conduction band is often higher than that of other semiconductor materials, and it can be used as a selective contact material for holes in perovskite solar cells. Compared with silicon, the conduction band position of NiOx _is much higher than that of silicon (~2eV), while the valence band position is slightly lower than that of silicon (<0.3eV). Therefore, if p-type doped NiO _x forms a heterojunction with silicon, the barrier difference of the conduction band at the heterojunction interface can prevent photogenerated electrons from approaching the heterojunction interface. Although the valence band will also form a potential barrier to holes at the interface, due to the small barrier energy, it will not have a significant impact on the transport of photogenerated holes. Moreover, the barrier difference of the valence band at the interface will bend the valence band of silicon near the heterojunction interface, which is beneficial to the improvement of the open circuit voltage.

The Si/NiO _x heterojunction solar cell proposed by the utility model can use different back electric fields, such as an n-type silicon doped layer prepared by a diffusion process, or an intrinsic amorphous silicon passivation layer and an n-type amorphous silicon heavily doped layer, or n-type doped _TiOx layer. Various forms of back electric field can make full use of existing crystalline silicon solar cell production equipment, avoiding repeated investment in equipment. In addition, the crystalline silicon heterojunction solar cell proposed by the utility model has a double-sided light-incoming structure, which can make full use of sunlight resources and increase the actual power generation of photovoltaic modules.

The crystalline silicon solar cell based on the Si/ _NiOx heterojunction proposed by the utility model can effectively reduce the recombination of photogenerated carriers inside the solar cell, thereby improving its photoelectric conversion efficiency. The back electric field structure of the crystalline silicon heterojunction cell proposed by the utility model can fully utilize the existing crystalline silicon solar cell production equipment for production, reducing investment in equipment. In addition, the crystalline silicon heterojunction cell proposed by the utility model adopts a double-sided light-incoming structure, which can make full use of sunlight and increase the actual power generation of photovoltaic modules.

Description of drawings

Accompanying drawing 1 is the structure diagram of the solar cell of the present utility model.

detailed description

The utility model will be further illustrated by the following examples.

Example 1.

(1) Preliminary cleaning of silicon wafers, double-sided texturing.

(2) Prepare the back n-type doped layer by using a diffusion process.

(3) Deposit a silicon nitride or aluminum oxide passivation layer on the back, and then prepare a grid-shaped Ag electrode.

(4) Perform secondary cleaning on the front side of the silicon wafer.

(5) The NiO _x layer was prepared on the front side of the silicon wafer using atomic layer deposition.

(6) Deposit the ITO transparent conductive layer and the Ag metal grid line to prepare the front electrode.

Example 2.

(1) Preliminary cleaning of silicon wafers, double-sided texturing.

(2) Use hydrofluoric acid to remove the oxide layer on the surface of the silicon wafer, and use plasma-enhanced chemical vapor deposition to prepare an amorphous silicon passivation layer and an n-type heavily doped amorphous silicon emitter.

(3) Deposit ITO as a transparent conductive layer, deposit Ag metal grid lines, and prepare the back electrode.

(4) The silicon wafer was reversed, and the NiO _x layer was prepared by chemical vapor deposition.

(5) Deposit ITO as a transparent conductive layer, deposit Ag metal grid lines, and prepare front electrodes.

Example 3.

(1) Preliminary cleaning of silicon wafers, double-sided texturing.

(2) The _NiOx layer is deposited using an evaporation process.

(3) Deposit AZO as a transparent conductive layer, deposit Cu metal grid lines, and prepare front electrodes.

(4) The silicon wafer is transferred, and the TiO _x layer is prepared by atomic layer deposition.

(5) Deposit the ITO transparent conductive layer and the Ag metal grid line to prepare the back electrode.

Claims (6)

1. A crystalline silicon solar cell based on Si/NiO _x heterojunction is characterized in that it comprises a front electrode, a NiO _x layer, a crystalline silicon absorber layer, a back electric field, and a back electrode; its structure is followed successively from the light-facing surface: Front electrode, NiO _x layer, crystalline silicon absorber layer, back electric field, back electrode. 2. The crystalline silicon solar cell according to claim 1, characterized in that the NiO _x layer is p-type doped. 3. The crystalline silicon solar cell according to claim 1, characterized in that the crystalline silicon absorption layer is doped with n-type or p-type. 4. The crystalline silicon solar cell according to claim 1, characterized in that the back electric field is in the following three forms: an n-type doped layer plus a silicon nitride passivation layer, or an intrinsic amorphous silicon passivation layer Add n-type amorphous silicon heavily doped layer, or n-type doped _TiOx layer. 5. The crystalline silicon solar cell according to claim 1, characterized in that said front electrode comprises a transparent conductive layer and a metal grid electrode. 6. The crystalline silicon solar cell according to claim 1, characterized in that the back electrode is a transparent conductive layer and a metal grid electrode, or a metal grid electrode.