Two Basic Structures of Thin Film Solar Cells

Thin-film solar cells in accordance with the type of substrate can be divided into two types: one using a transparent substrate, the front wall type; the other using opaque substrate, the back wall type. In the "front wall" design, the sun through the transparent substrate into the PN junction,lifePo4 battery usually glass or transparent plastic. Substrate insulation, you need to deposit a layer of transparent conductive film (TCO), and then in the TCO on the corresponding deposition of silicon or compound materials, the formation of PN junction, and finally deposited on the back layer of a layer of back reflection, the back reflection layer at the same time In the "back wall" design, the sunlight directly into the PN junction, in this structure, the deposition sequence and just the "front wall type" design of the opposite: first deposited back reflection layer, and then PN Finally, a layer of transparent conductive film, as the top electrode and the junction of the window layer. Cadmium telluride batteries and most of the amorphous silicon cells are used "front wall" design, CIS lifePo4 batteries and part of the amorphous silicon cell using "rear wall" design.

Amorphous silicon thin film solar power battery manufacturing process

The structure, working principle and fabrication process of thin film solar cells are described using "front wall" type amorphous silicon thin film solar cells as an example.

Structure and working principle of amorphous silicon thin film

The rigid amorphous silicon solar cell consists of a transparent conductive film (TCO) on the water-white glass), a type amorphous silicon P, an intrinsic layer amorphous silicon i, an N-type amorphous silicon, and an aluminum thin film. The electrons pass through glass into the i-layer amorphous silicon, which is separated by the p-i-n junction. The photogenerated voltage is formed between the TCO and the aluminum film, and the photocurrent is flowed after the load.

Preparation of Transparent Conducting Films

Transparent conductive film (TCO) used as the front contact electrode of amorphous silicon solar cells, usually by the SnO2: F composition, its main requirements are: ① high light transmittance; ② low resistivity; ③ uniform Good. Preparation of transparent conductive film, the first with a neutral detergent to clean the glass substrate, and then rinse with deionized water and drying.

The formation of the intrinsic layer deposition i layer of gas for the SiH4 and H2 gas mixture, in the deposition of intrinsic layer before the use of a large number of electronic grade SiH4 washing deposition chamber and related gas, try to avoid contamination of various impurity atoms. The a-Si: H solar cell has two requirements for the intrinsic layer. One is to minimize the space charge density in the intrinsic layer and improve the lifetime and migration of the photogenerated carriers. Rate, in determining the intrinsic layer thickness, to improve the junction of the electric field, thereby enhancing the photogenerated carrier collection efficiency and stability of the lifePo4 battery pack; the second is to require a suitable thickness, as much as possible to increase the intrinsic layer of light absorb. The a-Si: H intrinsic layer depends on the RF power, the substrate temperature, the reaction pressure and the gas flow rate during the preparation. In addition, SiH4 is diluted with H2, the a-Si: high.

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