Heterojunction solar cell and preparation method thereof

Abstract

The invention provides a heterojunction solar cell. The heterojunction solar cell comprises a first thin film provided with a first electric conduction type, an active area, and a second thin film provided with a second electric conduction type, wherein the active area and the second thin film are sequentially arranged on the surface of the first thin film; a first gradual change buffer layer which is heterogeneous with the first thin film is further arranged between the first thin film and the active area, and a second gradual change buffer layer which is heterogeneous with the second thin film is further arranged between the second thin film and the active area. The invention further provides a preparation method of the heterojunction solar cell, which comprises the following steps: 1), growing the first gradual change buffer layer heterogeneous with the first thin film on the exposed surface of the first thin film; 2), growing the active area epitaxially on the exposed surface of the first gradual change buffer layer; 3), growing the second gradual change buffer layer on the exposed surface of the active area; and 4), growing a second thin film layer heterogeneous with the second gradual change buffer layer on the exposed surface of the second gradual change buffer layer, and the electric conduction types of the first thin film and the second thin film are opposite.

Description

technical field [0001] The invention relates to the field of solar cells, in particular to a heterojunction solar cell and a preparation method thereof. Background technique [0002] With the aggravation of environmental pollution and energy crisis, people are full of expectations for the utilization of new energy sources (especially solar cells based on completely harmless sunlight). Some solar cell materials are affected by doping and composition, and using their heterostructures can avoid the above problems, so P-N or P-I-N solar cells containing such heterostructures are getting more and more attention. When using a heterojunction, due to the problem of lattice mismatch, not only there are too many lattice defects in the conventionally grown material, but also the potential barrier of the heterojunction will hinder the transport and collection of carriers, which is not conducive to improving The efficiency of solar cells. In view of this, solar cells based on gradient ...

AI Technical Summary

Problems solved by technology

like figure 1 , Figure 2A , Figure 2B , Figure 2C and Figure 2D As shown, according to this method, during the growth process of the active region 202, a material with a large difference in lattice constant between the N-type layer and the P-type layer is directly grown. Due to the high degree of lattice mismatch, the stress release during the growth process There will be a large number of misfit dislocations, such as Figure 2C As shown by the dislocation 208 in , which reduces the crystalline quality of the material and thus affects the performance of the solar cell

At the same time, due to the large material difference between the active region and the N-type and P-type layers, the contact barrier is relatively high, such as the simplified energy band structure diagram of a traditional mismatch system solar cell, that is Figure 5A As shown, this is not conducive to the transport of carriers, which will reduce the efficiency of solar cells

Images