Preparation method of light-absorption layer of thin-film solar cell

Abstract

The invention discloses a preparation method of a light-absorption layer of a thin-film solar cell. The method comprises the following steps of preparing a copper-indium-gallium prefabricated layer; preparing a selenium thin-film layer on the copper-indium-gallium prefabricated layer, wherein the molar ratio of selenium to the sum of copper and gallium is greater than 1; placing the copper-indium-gallium prefabricated layer in an annealing furnace, heating the copper-indium-gallium prefabricated layer to a first preset temperature, and keeping the first preset temperature for a first preset time period; heating the copper-indium-gallium prefabricated layer from the first preset temperature to a second preset temperature, keeping the second preset temperature for a second preset time periodto conduct selenization on the prefabricated layer, and then extracting selenium steam from the annealing furnace; heating the copper-indium-gallium prefabricated layer from the second preset temperature to a third preset temperature, then keeping the third preset temperature for a third preset time period, and introducing hydrogen sulfide gas within the third preset time period to vulcanize theprefabricated layer, so as to prepare the copper-indium-gallium selenide sulfide light-absorption layer. According to the method, the selenization and vulcanization of the copper-indium-gallium prefabricated layer are carried out step by step at different temperatures, so that excessive selenization and nonuniformity are avoided, the vulcanization quality is ensured, and the quality of the light-absorption layer is improved.

Description

technical field [0001] The invention belongs to the technical field of solar cells, and in particular relates to a method for preparing a light-absorbing layer of a thin-film solar cell. Background technique [0002] Copper indium gallium selenide (CIGS) thin-film solar cell is a kind of high-efficiency thin-film solar cell, which has the advantages of high stability, low cost and long life. Copper indium gallium selenide thin film solar cell is essentially a direct bandgap semiconductor, and its basic structure includes a substrate, a back electrode, a light absorption layer, a buffer layer, a window layer, an antireflection layer and a metal electrode layer that are stacked in sequence. The photoelectric absorption layer is a compound semiconductor film composed of four elements: copper, indium, gallium and selenium. At present, there are mainly co-evaporation and sputtering selenization methods for preparing copper indium gallium selenide light absorbing layer. The sputt...

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Problems solved by technology

In this high-temperature selenization vulcanization process, although the vulcanization can be effectively carried out and the bandgap width can be increased, the selenization and vulcanization processes cannot be precisely controlled separately. The degree of selenization and sulfuration in the film area is different, resulting in poor film uniformity and low repeatability, and it is difficult to guarantee the quality of the light-absorbing layer in industrial production

At the same time, although this one-step process of selenization and sulfide is simple and time-saving, the activity of sulfur is high at high temperature, and the simultaneous sulfidation and selenization will cause a large amount of sulfur to enter the copper indium gallium selenide absorbing layer. Internally, the internal bandgap width is increased, so the bandgap width of the entire light-absorbing layer cannot reach the recognized best V-shaped distribution, which will reduce the photoelectric conversion rate of the thin-film battery

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