Gradient band gap nano-silicon thin film and graded band gap nano-silicon thin film solar cell

Abstract

The invention discloses a graded bandgap nano-silicon film and a graded bandgap nano-silicon film solar cell. The graded bandgap nano-silicon film is a mixed phase material consisting of noncrystalline silicon, crystal grains and a crystal boundary, wherein a bandgap of crystalline silicon is 1.12eV; a bandgap of the noncrystalline silicon is 1.75eV; a crystalline fraction scope of the device-level nano-silicon film is 40-70%; and a bandgap of the graded bandgap nano-silicon film is 1.3-1.5eV. The graded bandgap nano-silicon film is used for an I layer (namely a light absorption layer) of the nano-silicon cell, absorbs sunlight energy in different wavebands sufficiently, improves transmission of photoproduction holes, and therefore can effectively improve the photoelectric conversion efficiency of the cell; in addition, a graded light absorption layer structure solves the problem that the open circuit voltage of the nano-silicon solar cell is lower; the graded structure allows bandgap differences between the I layer and a P layer and between the I layer and an N layer to be less; the problem of bandgap mismatch of P / I and I / N interfaces is solved to a greater extent; the interfacial effect of a heterojunction is avoided; the photoinduced degradation effect is reduced; and the cost is lowered.

Description

technical field

[0001] The invention relates to the field of silicon thin-film solar cells, in particular to a nano-silicon thin film with a gradient band gap and a solar cell made of the nano-silicon thin film. Background technique

[0002] Silicon thin-film solar cells have the advantages of less raw material consumption, easy large-area continuous production, and less pollution in the preparation process; they are an important development direction of photovoltaic cells. Amorphous silicon cells have a light-induced degradation effect, which limits its development. Nano-silicon (microcrystalline silicon) solar cells have good material order and basically no degradation, and can be combined with amorphous silicon cells to prepare stacked cells to improve Efficiency and cost reduction. Existing nano-silicon thin-film solar cells cannot fully absorb solar light energy in different bands, have low power conversion efficiency, large light-induced attenuation, and low open-circ...

Examples

Embodiment Construction

[0026] The graded bandgap nano-silicon thin film material in this specific embodiment is a mixed-phase material composed of amorphous silicon, crystal grains and grain boundaries. The band gap of the selected crystalline silicon is 1.12eV, and that of amorphous silicon is 1.75eV; the crystallization rate of nano-silicon thin film (the ratio of crystal phase to amorphous phase) ) ranges from 40% to 70%; by controlling the crystallization rate to change within the aforementioned range, the bandgap of the nano-silicon thin film with graded bandgap is 1.3eV~1.5eV. The method of controlling the crystallization rate includes adjusting the core preparation parameters of the nano-silicon thin film, such as the concentration of silane (SC), the level of the preparation power and the level of the preparation pressure, etc.

[0027] The graded bandgap has multiple structures, and the present invention proposes four schemes, the first such as figure 1 As shown in , a "C" type graded stru...

technical field

[0001] The invention relates to the field of silicon thin-film solar cells, in particular to a nano-silicon thin film with a gradient band gap and a solar cell made of the nano-silicon thin film. Background technique

[0002] Silicon thin-film solar cells have the advantages of less raw material consumption, easy large-area continuous production, and less pollution in the preparation process; they are an important development direction of photovoltaic cells. Amorphous silicon cells have a light-induced degradation effect, which limits its development. Nano-silicon (microcrystalline silicon) solar cells have good material order and basically no degradation, and can be combined with amorphous silicon cells to prepare stacked cells to improve Efficiency and cost reduction. Existing nano-silicon thin-film solar cells cannot fully absorb solar light energy in different bands, have low power conversion efficiency, large light-induced attenuation, and low open-circ...

Examples

Embodiment Construction

[0026] The graded bandgap nano-silicon thin film material in this specific embodiment is a mixed-phase material composed of amorphous silicon, crystal grains and grain boundaries. The band gap of the selected crystalline silicon is 1.12eV, and that of amorphous silicon is 1.75eV; the crystallization rate of nano-silicon thin film (the ratio of crystal phase to amorphous phase) ) ranges from 40% to 70%; by controlling the crystallization rate to change within the aforementioned range, the bandgap of the nano-silicon thin film with graded bandgap is 1.3eV~1.5eV. The method of controlling the crystallization rate includes adjusting the core preparation parameters of the nano-silicon thin film, such as the concentration of silane (SC), the level of the preparation power and the level of the preparation pressure, etc.

[0027] The graded bandgap has multiple structures, and the present invention proposes four schemes, the first such as figure 1 As shown in , a "C" type graded stru...

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