Method for preparing point contact electrode at back of solar cell by utilizing laser induced thermit reaction

Abstract

The invention discloses a method for preparing a point contact electrode at the back of a solar cell by utilizing laser induced thermit reaction, which comprises the following steps in sequence: plating a passivation media layer on the back of a silicon substrate; steam-plating an aluminum layer on the passivation media layer; printing or coating thermite on the aluminum layer; and igniting the thermite by the radiation of laser to result in the thermit reaction for generating high temperature so that the aluminum layer and the silicon substrate are molten and then are crystallized and form better ohmic contact and aluminum back surface field. The invention adopts laser to indirectly sinter an electrode, i.e. the laser is used to induce spontaneous reaction of the thermite, high temperature generated by the reaction make aluminum and the silicon from better ohm contact, therefore, the prepared solar cell has smaller series resistance; meanwhile, the aluminum and the silico forms the aluminum back surface field, and the prepared solar cell has bigger short circuit current. By adopting the method of the invention, the laser does not directly radiate a metallic film, which reduces the damage to the silicon to be lowest and further improves the short circuit current of the solar cell.

Description

technical field [0001] The invention belongs to the technical field of solar energy, and in particular relates to a method for preparing solar cell electrodes. Background technique [0002] Exploring new processes for solar cells to reduce costs while improving conversion efficiency is the only way to industrialize solar energy. The recombination on the back surface of the silicon wafer has a great influence on the efficiency of solar cells. The existing electrode sintering process forms a metal-semiconductor interface on the entire back of the solar cell, which has a high minority carrier recombination speed, resulting in low short-circuit current of the solar cell. Therefore, the back electrode of the point contact method has attracted more and more attention. It can reduce the area of ​​the metal-semiconductor contact area, thereby effectively reducing the surface recombination rate of the solar cell, and has a great effect on improving the performance of the solar cell,...

AI Technical Summary

Problems solved by technology

However, the existing laser sintered electrode (LFC) process uses laser light to directly irradiate the surface of the metal film (such as aluminum Al? The energy stability of the electrode is poor. After the metal film used as an electrode is irradiated by pulsed laser, if the pulsed laser energy is too small, the sintering temperature cannot be reached, so that ohmic contact cannot be formed; if the pulsed laser energy is too large, the pulsed laser The metal film will be evaporated, and only the ohmic contact will be formed in the peripheral area of ​​the ablation pit. The solar cell produced has a high series resistance. At the same time, the laser will cause great damage to the battery material, and the short-circuit current of the prepared battery is low.

Second, even if the pulse laser energy is appropriate, the laser will damage the material under the electrode to a certain extent, which also reduces the short-circuit current of the battery to a certain extent.

Images