Preparation method and purpose of top cell P type layer of amorphous silicon germanium thin-film solar cell

Abstract

The invention discloses a preparation method and purpose of a top cell P type layer of an amorphous silicon germanium thin-film solar cell. According to the method, a P type layer of a top cell is prepared by a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method; and reactant gas includes hydrogen, silane, and borane. During deposition, gas flow volume proportion of the hydrogen to silane to borane is maintained to be 150 to 200 : 1 : 3 to 8; the borane is borane- hydrogen mixed gas, wherein the borane volume concentration is 0.5%; the air pressure is 160 to 220 Pa; the preparation temperature is within 100 DEG C; the power density inside the cavity is over 300mW / cm<2>; and the band gap width of the P type layer is over 2.0 eV. With the P type layer, the top cell can obtain the high open-circuit voltage and the short-circuit current density can be reduced properly and thus the short-circuit currents generated by the top cells in all sub cells of dual-junction and three-junction cells are the lowest ones, thereby forming a top cell current limitation effect. Therefore, current matching among all sub cells and the fill factors of the integrated cells can be effectively improved, thereby improving the photoelectric conversion efficiency of the dual-junction and three-junction amorphous silicon germanium thin-film solar cells.

Description

technical field [0001] The invention belongs to the field of silicon-based thin-film solar cells, and relates to an amorphous silicon-germanium thin-film solar cell; specifically, it relates to a preparation of a new type of P layer used for top cells of double-junction and triple-junction amorphous silicon-germanium thin-film solar cells Methods and uses. Background technique [0002] Among various thin-film batteries, amorphous silicon (a-Si:H) thin-film solar cells are the earliest and most researched thin-film batteries. Due to the wide band gap of the amorphous silicon thin film material itself, the absorption of long-wave light in the solar spectrum is insufficient, which limits the further improvement of cell efficiency. In order to broaden the effective absorption range of the solar spectrum, the amorphous silicon germanium (a-SiGe:H) material with a lower bandgap width and continuously adjustable is applied to the battery, and the amorphous silicon / amorphous silico...

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Problems solved by technology

[0003] Due to the series structure between the sub-cells, the final current output of the battery is determined by the sub-cell that produces the smallest current, so the current matching between the sub-cells is very important. In the preparation of double-junction and triple-junction amorphous silicon When using germanium batteries, the main problem is that sunlight is mainly absorbed by the top cell, and the remaining light effectively absorbed by the middle cell and the bottom cell is insufficient, resulting in high current in the top cell and low current in the middle cell and bottom cell. The total current output

If the thickness of the top cell is blindly reduced, the open circuit voltage of the top cell will easily decrease, which will lead to a drop in the total voltage of the cell and affect the improvement of the photoelectric conversion efficiency of the cell.

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